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Chlamydia is a leading cause of early infant pneumonia and conjunctivitis in newborns arthritis medication horses 25 mg indomethacin buy overnight delivery. The etiology of chlamydia is the gram-negative coccus bacterium Chlamydia trachomatis arthritis hand gloves indomethacin 75 mg order otc. This may be due to male-to-female transmission being more likely than female-to-male transmission cortisone injections for arthritis in back 75 mg indomethacin order overnight delivery. The herpes virus goes latent and can become active from time to time, causing an outbreak of blisters arthritis of fingers exercises indomethacin 25 mg without a prescription. Babies born to infected mothers can be exposed to the virus during the birthing process arthritis psoriatica diet buy 50 mg indomethacin amex. If a woman has active genital herpes at delivery, a cesarean delivery is usually performed. There is no treatment that can cure herpes, but antiviral medications can shorten outbreaks and make them less severe. Signs and symptoms in men may include itching or irritation inside the penis, burning after urination or ejaculation, or penile discharge. Signs and symptoms in women may include itching, burning, redness or soreness of the genitals, discomfort with urination, or a thin discharge with an unusual smell that can be clear, white, yellowish, or greenish. Genital Warts Genital warts are benign neoplastic growths on the epidermis of the genitals. If you know you are infected you can take steps to protect yourself and your partners. Genital warts may appear within weeks after sexual contact with an infected partner, or they might not develop for several months. Genital warts are diagnosed by physical examination and can be removed by medications that erode the wart tissue. Screening for Prostate Cancer: Systematic Review and Meta-analysis of Randomised Controlled Trials. Estimating Menstrual Blood Loss in Women with Normal and Excessive Menstrual Fluid Volume. An Estimate of the Global Prevalence and Incidence of Herpes Simplex Virus Type 2 Infection. Measured Blood Loss, Clinical Features, and Outcome in Women with Heavy Periods: A Survey with Follow-up Data*1. Sexually Transmitted Diseases Among American Youth: Incidence and Prevalence Estimates, 2000. A 16-year-old, sexually active woman complains of a green, frothy, foul-smelling vaginal discharge. A 63-year-old male says he gets up several times a night to urinate but has difficulty getting urination started. Describe how she can reduce the risk of transmission of the infection to her sexual partner. Why do many physicians sometimes recommend active surveillance for prostate cancer When baby Christopher was born, the pediatrician discovered that his left testicle had not descended into the scrotum. The most important risk factor for cervical cancer is infection by the human papillomavirus. Chapter 12 Diseases and Disorders of the Endocrine System Learning Objectives After studying this chapter, you should be able to í Describe the functions of the endocrine glands and the hypothalamus Identify the various hormones and their functions Describe the consequences of hyposecretion and hypersecretion of endocrine hormones Describe the incidence, risk factors, signs and symptoms, etiology, diagnosis, treatment, and prevention for diseases and disorders of the endocrine system Identify age-related changes in endocrine function Pituitary carcinoma. Urine production in diabetes insipidus patients can reach 20 liters (about 5 gallons) per day. No treatment or cure existed for this mysterious ailment, which killed children and whose complications crippled survivors. It was not until the late 19th century, when diabetes was observed in dogs whose pancreas had been removed experimentally, that the disease could be linked to a specific organ. The key component of the pancreas was eventually isolated and identified as the protein hormone insulin. Early diagnosis, treatment, and effective management have lengthened and greatly improved the lives of diabetics. In addition, endocrine tissues are found in the heart, stomach, intestines, kidneys, and thymus. Endocrine hormones affect many aspects of body functions, including growth, development, energy metabolism, muscle and fat distribution, sexual development, fluid and electrolyte balance, inflammation, and immune responses. Hormones are secreted from endocrine glands into the bloodstream, and they affect the functions of cells at distant sites. Some hormones affect the whole body, while others act only on target or distant organs. The pituitary itself is controlled by the hypothalamus, which is the homeostatic center of the body and is part of the central nervous system. Another hormone, glucagon, works antagonistically to insulin and is released when the blood sugar level falls below normal. Hormones are potent chemicals, so their circulating levels must be carefully controlled. Its importance becomes clearer as specific diseases of the endocrine system are considered. Thalamus Hypothalamus Midbrain Hypothalamus Stalk Pituitary Bony depression of skull bone (sella turcica) Releasing factors from hypothalamus Hormones traveling on nerve fibers Anterior pituitary (adenohypophysis) Pituitary Gland the pituitary gland is a pea-sized organ located at the base of the brain. Also called the hypophysis, the pituitary is composed of an anterior lobe called the adenohypophysis and a posterior lobe called the neurohypophysis. A stalk called the infundibulum connects the pituitary gland to the floor of the hypothalamus. Soft tissues-organs such as the liver, heart, and kidneys-also increase in size and develop under the influence of growth hormone. After adolescence, growth hormone is secreted in lesser amounts but continues to promote tissue replacement and repair. Adrenocorticotropic Hormone the anterior pituitary also regulates the adrenal glands. The adrenal glands have an inner part, the adrenal medulla, and an outer portion, the adrenal cortex. Gonadotropins the anterior pituitary regulates sexual development and function by means of hormones known as the gonadotropins. Prolactin Prolactin produced by the anterior pituitary stimulates breast development and formation of milk during pregnancy and after delivery. Oxytocin the target organ of oxytocin is the smooth muscle of the uterus, where it stimulates uterine contractions; the mammary glands, where in response to suckling it triggers the release of milk from the breasts; and the prostate gland, where it causes ejection of prostate gland secretions. A small amount of T3 is produced by the thyroid gland; however, most T3 is formed by conversion of T4 to T3. Parathyroid Glands the parathyroid glands are four tiny glands located posterior to the thyroid gland. Before the function of the parathyroid glands was understood, they were sometimes removed with a thyroidectomy. Calcium is essential to the blood-clotting mechanism, along with nervous conduction. It increases heart muscle tone and plays a significant role in muscle contraction. Each of the glands consists of two distinct parts: an outer adrenal cortex and an inner adrenal medulla. Chapter Twelve Diseases and Disorders of the Endocrine System í 271 Aldosterone causes sodium retention and potassium secretion by the kidneys. The sex hormones: androgens, the male hormones, and estrogens, the female hormones. The adrenal medulla secretes epinephrine, commonly called adrenalin, and norepinephrine. These hormones are secreted in stress situations when additional energy and strength are needed. Epinephrine causes vasodilation and increases heart rate, blood pressure, and respiration. Together, epinephrine and norepinephrine help shunt blood to vital organs when required. Endocrine Pancreas the pancreas is a fish-shaped organ that lies across the middle of the abdominal cavity, below the stomach. It is divided into a head, body, and tail, with the head nearest to the duodenum and the opening of the pancreatic duct. The endocrine functions of the pancreas consist of synthesis, storage, and release of insulin, glucagon, and somatostatin. Insulin is secreted by certain cells of the pancreas called beta cells, located in patches of tissue named the islets of Langerhans or pancreatic islets. Somatostatin, secreted by delta cells, inhibits the secretion of glucagon and insulin. The combined effect of these hormones maintains the normal level of blood glucose (80­120mg/dl). Insulin moves sugar out of the blood and into tissues, thus decreasing the blood sugar level. Any carbohydrates that are not needed for immediate energy by the cells are stored, mostly in the liver, as glycogen. If the blood sugar level drops, for example after fasting or sleeping, glucagon is secreted. Glucagon stimulates the liver to release glycogen in the form of glucose, thus raising the blood sugar level. Ovaries and Testes the gonads (ovaries and testes) function as endocrine glands as well as being the source of the ova and sperm. Estrogen and progesterone regulate sexual development, secondary sex characteristics, and the reproductive cycle in females. Testosterone regulates sexual development and secondary sex characteristics in males. Diagnostic Tests and Procedures Only the thyroid and testes can be physically examined. In these assays of blood or urine samples, labeled hormone (antigen) in the sample competes with unlabeled hormone for binding sites on an antibody that is in limited availability. If there is a very high concentration of hormone in the blood or urine sample, most of the resulting antigen­antibody complexes will be unlabeled. If there is a very low concentration of hormone in the blood or urine sample, most of the antigen­antibody complexes will be labeled. The manifestations of hypopituitarism depend on which hormones are lost and the extent of the hormone deficiency. Pituitary Dwarfism Pituitary dwarfism is due to inadequate secretion of growth hormone by the pituitary gland in children. An estimated 1 in 14,000 to 1 in 27,000 people have some type of dwarfism; pituitary dwarfism affects fewer than 200,000 people in the United States. Normal puberty may or may not occur, depending on the degree to which the pituitary gland can produce sufficient hormone levels other than growth hormone. Injury or trauma to the pituitary gland is the only known risk factor for pituitary dwarfism. Signs and symptoms include slowed growth before the age of 5 years, absent or delayed sexual development, and short stature and height for age. In most cases the cause of pituitary dwarfism is idiopathic; other causes may include genetics, tumor in the pituitary gland interfering with hormone production, trauma to the gland, or radiation treatment to the head. There is no known prevention except to prevent injury or trauma to the pituitary gland. Radiation therapy may be used in conjunction with surgery or in cases where surgery is not possible. Medications that reduce growth hormone secretion are also used for cases where surgery is not feasible. Acromegaly has an insidious onset, and signs and symptoms are usually present for a number of years before a diagnosis is made. The growth plates of the long bones are closed, so the long bones do not increase in length. Signs and symptoms may include enlargement of the hands, feet, and head; soft-tissue thickening of the palms of the hands and the soles of the feet; enlargement of the forehead; enlargement of the jaw that causes the teeth to spread; enlargement of the tongue; and arthritis. The treatment for acromegaly focuses on correcting metabolic abnormalities, improving adverse clinical features, and correcting the underlying cause. Surgical removal of tumors of the pituitary or hypothalamus is the treatment of choice. Medications that decrease growth hormone secretion may be administered prior to surgery or, in cases where surgery is not possible, to shrink the tumor. Radiation is also used to shrink the tumor and is used when medication therapy fails and in cases where surgery is not an option. Prevention is not possible; however, early treatment may reduce or prevent worsening of complications of this disorder. In patients with gigantism, facial features may thicken, the hands and feet may be disproportionately enlarged, and headaches may develop along with excess sweating and late onset of puberty. The effects of these disorders can be reduced in some cases by early intervention with hormone therapy. Keep regular doctor appointments and monitor the growth of newborns, infants, and young children to identify problems early. Risk factors include head injury, brain surgery, kidney disease, pregnancy, and taking certain medications (lithium, amphotericin B, demeclocycline). The chief symptom of diabetes insipidus is the production of abnormally large amounts of urine, or polyuria. Excessive urination is often accompanied by extreme thirst and a corresponding increase in fluid intake (polydipsia).

Impetigo is the diagnosis; Staphylococcus aureus or Streptococcus pyogenes are potential causes arthritis in back and feet purchase indomethacin no prescription. Possible causes of the rash include tinea cruris, candidiasis, pediculosis, and scabies arthritis neck head symptoms buy indomethacin once a day. Basal cell carcinoma or squamous cell carcinoma are possible diagnoses; treatment includes a visual examination and biopsy arthritis differential diagnosis indomethacin 50 mg low price. Hormones, overproduction of sebum, bacteria, lack of or uneven exfoliation of skin cells arthritis pain hands 50 mg indomethacin order with mastercard. Treatment may include topical antibiotics and antibacterials, retinoid, oral antibiotics, oral contraceptives, and isotretinoin arthritis toes order indomethacin 75 mg line. Prevention of acne includes not overcleansing the skin, not using harsh scrubs, avoiding products with high concentrations of alcohol, and keeping the hands away from the face. False A-40 L Appendix C Interactive Exercises with herpetic lesions, or contact with skin that is shedding the virus. False Appendix D Prevention Plus Suggested Answers Chapter 1: Introduction to Disease Four Modifiable Risk Factors for Chronic Disease 1. Four modifiable risk factors for chronic disease are lack of physical activity, poor nutrition, tobacco use, and excessive alcohol consumption. Moderate alcohol consumption is defined as two drinks a day for men, one for women. The immune response takes from 10 days to 2 weeks to reach its peak because after initial exposure to the antigen, lymphocytes need to become activated, reproduce, and develop. You should get a vaccine appropriate for your destination at least 2 weeks before your trip. Many people in the United States are vaccinated against childhood illnesses such as measles, pertussis, and chickenpox. While in the United States, your relative should take the same precautions that you do to protect from infectious diseases. Chapter 4: Cancer Chapter 2: Immunity and Disease Epinephrine Treatment for Life-Threatening Allergic Reactions 1. Epineprhine is a prescription medication because it could be dangerous if injected when not suffering from a life-threatening allergic reaction. Injection of epinephrine into the thigh muscle offers the fastest systemic absorption. When suffering life-threatening anaphylaxis the speed at which epinephrine is absorbed is critical. If not absorbed quickly, the patient could die before adequate levels of epinephrine are achieved. A-41 A-42 í Appendix D Prevention Plus Suggested Answers Chapter 6: Diseases and Disorders of the Cardiovascular System Risk Factors for Coronary Heart Disease 1. Modifiable risk factors for coronary heart disease include diet, exercise, and smoking. While genetics may predispose a person for disease, that person can reduce risk by eliminating behavioral and environmental factors. Chapter 9: Diseases and Disorders of the Gastrointestinal System Bacteria, Coolers, and Food Poisoning 1. At cold temperatures the chemical reactions of metabolism slow down too much to sustain life. However, the cold temperature does not damage the bacterial cell, its molecules, or metabolic machinery, so when temperatures increase, bacteria can grow again. At extreme temperatures like those used for cooking food, heat destroys bacterial cells, their molecules, and metabolic machinery. Iron is required for the synthesis of hemoglobin, so vegetarians are at risk for developing irondeficiency anemia. Meat contains heme iron, which is more easily absorbed than nonheme iron found in plants. To obtain iron and B12, they need to eat a variety of fruits, beans, and vegetables. Beans also provide protein as do foods such as eggs, peanut butter, Greek yogurt, cottage cheese, and soy milk. Therefore the benefits of screening for colorectal cancer outweigh the risks after approximately age 50. Young people should be screened if they have a family history of colon cancer, familial polyposis, or if they exhibit signs and symptoms that suggest colon cancer. Workers in the food service industry must use sanitary procedures when handling food, including the simple task of washing their hands. Health care workers receive vaccination against hepatitis B, and blood is screened for contamination by hepatitis B and C. Chapter 8: Diseases and Disorders of the Respiratory System Appropriate Antiobiotic Use 1. Antibiotics affect bacteria, not viruses, so they are not an appropriate treatment for a viral infection. This positive feedback loop persists until all of the sodium channels have opened. The depolarization spreads passively to adjacent regions of the membrane and activates nearby sodium channels. This wave of molecular conformational change and electrical activity propagates over the length or surface of the cell at velocities up to 120 m/s. Potential energy that is stored in the sodium concentration gradient is sequentially used along the propagation path. The propagation velocity is determined by the rate of molecular change and the electrical properties of the cell that control the spread of potential changes (cable properties). About 1 millisecond later, the sodium channels undergo a second conformational change and inactivate. The cycle is started by a depolarization and continues until all of the sodium channels have been activated. A depolarization first causes the channel to change from the resting state to the activated and open states and later to the inactivated state. Repolarization is required to go from the inactivated state back to the resting state. The membrane potential, Vm, is sensed as the difference between the inside potential, Vi, and the outside potential, Vo. Vm is compared to the command potential, Vc, and, if they are different a current flows through the axial wire and the cell membrane to make Vm equal to Vc. The outward movement of K+ carrying positive charge out of the cell produces the repolarization (the falling phase of the action potential). In mammalian myelinated axons, the repolarizing current passes through the (nonvoltagesensitive) potassium channels that produce the resting potential. Working with giant nerve axons isolated from squid, they were able to break the positive feedback loop and measure the effect of a change in membrane potential in the ionic permeabilities without any change to the membrane potential due to the movement of ions. A pair of electrodes measures the membrane potential; this is then compared with a desired command potential. If the membrane potential is different from the command potential, a current is made to flow through the membrane in a direction that reduces the difference. The first is the charge movement necessary to change the potential or change the charge on the membrane capacitance. Then there is an inward current that is replaced in a few milliseconds by an outward current, which lasts as long as the pulse. It inactivates or decreases during the pulse, even though the membrane potential is kept at 0 mV, whereas the K current remains for the duration of the pulse. Larger pulses produce less inward Na current until, at about +60 mV, no net current passes through the Na channels. If the ratio of the sodium concentrations bathing both sides of the membrane is changed, this reversal potential also changes. With modest depolarizations, the inward current increases because larger pulses open more sodium channels. However, the less negative potential decreases the inward driving force on the sodium ions; after most of the NaV channels have been opened, still larger depolarizations decrease the Na current. When the membrane potential exceeds the sodium equilibrium potential, Na is forced out of the cell through the open NaV channels. In a free-running action potential, the membrane potential never exceeds the sodium equilibrium potential and there is always a net entry of Na into the cell. On the one hand, depolarization will increase the probability that NaV channels open and permit inward current, which will lead to further depolarization. On the other hand, depolarization moves the membrane potential further away from the potassium equilibrium potential, increasing the net driving force on potassium ions and thus producing an outward current through the resting potential potassium channels, which will lead to repolarization. If a sufficient number of sodium channels are opened so that the inward sodium current exceeds the outward potassium current, the cell has exceeded threshold and will continue to depolarize until all of the available sodium channels have opened. Treatments that reduce the sodium current-for example, reducing extracellular sodium concentration or reducing the number of NaV channels-will elevate the threshold. The recovery from inactivation shown by a two-pulse experiment with different amounts of time at the resting potential between pulses. The rate of recovery from inactivation is also voltage-dependent, as the channels recover more rapidly at more hyperpolarized potentials. The K current increases and becomes more rapid as the membrane potential is increased. Above about +20 mV, the increase in amplitude becomes proportional to the change in potential, indicating that all of the channels are open and that only the driving force continues to increase. The gating current is a direct sign of the conformational changes in the NaV channel proteins. As the pulse is made progressively more positive and more sodium channels open, the amplitude of the gating current grows and the currents become more rapid. Above about +20 mV, these two changes are complementary and the area under the gating current trace is constant, indicating that all of the channels are undergoing conformational changes and are doing so more rapidly at more positive potentials. The capacitance current increases linearly with the size of the pulse because it requires more charge to change the voltage by larger amounts. Hodgkin and Huxley separated the currents and showed how the ionic currents were proportional to the driving force on the ions. They created mathematical equations that emulated the amplitude and time course of the permeability changes and showed that these equations could predict the amplitude and time course of action potentials as well as their threshold, conduction velocity, refractory period, and several other features. Their concept of describing ionic current as the product of conductance times driving force is used to describe most of the remaining electrophysiological phenomena in all cells and tissues. In order to recover from inactivation and be available to open again, the NaV channels must spend some time with the membrane potential near the resting potential. During this recovery, the axon is said to be refractory because it is resistant to stimulation. During the absolute refractory period, so few NaV channels have recovered that even if all of the recovered channels were opened, there would be insufficient sodium current to exceed the outward potassium current, which tends to restore and maintain the resting potential. During the relative refractory period, a larger depolarization is required because a larger fraction of the available NaV channels must be opened to obtain the same number of channels opened in the first stimulus. In addition, in many nerve and muscle cells, there are more open potassium channels immediately following an action potential, which also makes the cell more difficult to excite a second time. During the absolute refractory period no stimulus, however large, can elicit a second action potential. During the relative refractory period a second action potential can be elicited but it requires a larger stimulus than that in the resting state. Accessory cells wrap nerve axons with many layers of their own membrane, electrically insulating most of the cell. The Na current enters the cell only at these nodes; excitation "jumps" from node to node in what is called saltatory conduction. The spread between nodes is the same passive spread seen in unmyelinated nerve cells, but it is more effective, that is, it produces a more rapid conduction velocity. The myelin wraps increase the resistance between the axoplasm and the surrounding media, which, in turn, increases the length constant for passive spread. The myelin also increases the effective thickness, which decreases the effective capacitance and reduces the amount of charge required to change the potential. Perhaps the most familiar is the conduction of acute pain information, which is frequently treated with local anesthetics; these act by blocking the NaV channels. Some forms of epilepsy and some cardiac arrhythmias are also treated with NaV channel blockers. Hypocalcemia is associated with increased excitability of nerves and skeletal muscle and may produce uncontrollable muscle contraction (tetany). The positive charge on the calcium ion repels the positively charged S4 helix, making it the effect of myelination on the longitudinal spread of current. In the upper diagram Na+ is shown entering (colored arrow) at a node of Ranvier and the associated current loops are shown in black. In an unmyelinated nerve (lower diagram) the same current loops occur but over a shorter distance; hence, the action potential propagates more slowly. The result is that, in low calcium conditions, the sodium channel opens in response to a smaller stimulus or even spontaneously at the resting potential. The calcium binding does not change the resting potential as measured with electrodes in the bulk compartments on both sides of the membrane. The symptoms can be eased by providing air conditioning or moving to a cooler climate. Cooling helps, somewhat paradoxically, because although it slows the opening of sodium channels and thereby slows the propagation velocity, it also slows the inactivation of NaV channels and increases the duration of the action potentials; thus, the greater Na+ influx makes the propagation more reliable. In healthy individuals, the 100-mV action potential that arrives at the next node of Ranvier is about five times larger than the 20-mV depolarization required for initiating a new impulse at that node. There are also compounds that chronically activate NaV channels, such as veratridine, pyrethroid insecticides, and brevetoxin, one of the red-tide toxins. One deflection occurs as the impulse passes the first wire and the second occurs as it passes the second wire.

Contrary to popular memory, boys and girls derived a similar small benefit from longer therapy yoga arthritis pain 50 mg indomethacin purchase visa. Of course, this type of analysis cannot determine the value of duration of continuation therapy in regimens not studied, but cross-study consistency lends weight to its conclusions arthritis in dogs glucosamine dosage order indomethacin toronto. The debate continues as to whether more effective postinduction intensification will allow briefer maintenance therapy or, conversely, will add value to longer therapy as more patients are brought to 24 months in remission arthritis diet juice cheap indomethacin online amex. Optimal duration of therapy may differ among subsets, being more important in standard-risk patients and less important in older or T-cell patients rheumatoid arthritis child indomethacin 50 mg otc. All patients received vincristine and prednisone pulses every 4 weeks and intrathecal methotrexate every 12 weeks arthritis pain in your hands indomethacin 75 mg order on-line. Several clinical trials have demonstrated that treatment with pediatric protocols, which utilize high cumulative doses of vincristine, corticosteroids, and asparaginase, particularly during periods of myelosuppression, significantly improves outcomes in this population. Infants with Acute Lymphoblastic Leukemia Infants 12 months of age or younger may present with a constellation of features that portend an unfavorable outcome and this group of patients routinely receives separate treatment regimens that are tailored to their unique features. Most relapses occur during treatment or within the first 2 years off therapy, although late relapses have been reported many years after diagnosis. Rare extramedullary sites include isolated leukemic infiltration of the lymph nodes, eyes, and bone. Time to relapse, or duration of first remission, is also a critical feature, with patients with early (<18 months from initial diagnosis) or intermediate (18 to 36 months) relapses faring more poorly than those with late relapse >36 months from initial diagnosis. Other groups have confirmed the importance of time to relapse and site of relapse211,219 as well as T-cell immunophenotype. Eight children were labeled mentally retarded and were receiving special education assistance. Younger children and those with seizures or structural brain abnormalities had the poorest cognitive outcomes. Of these, 17% had signs or symptoms of leukoencephalopathy, presenting with seizure in 85% and ataxia, memory loss, and motor and cranial nerve deficits in others. Of children with prior cranial irradiation, 27% had significant neurotoxicity compared to 15% of children who did not (P = 0. Twelve patients had progressive neurologic deterioration despite the cessation of intrathecal therapy. This is usually successful with agents similar to those used at initial presentation, more so in late than in early relapse. Outcomes improve with an increasing duration of first remission,216,217 with protocol as opposed to ad hoc therapy,219 and less certainly with increasing intensity of otherwise somewhat effective therapy. Thus, isolated extramedullary relapse usually represents a failure of systemic therapy, not only local therapy. Three-agent methotrexate, hydrocortisone, and cytosine arabinoside therapy was no more effective than twoagent methotrexate and hydrocortisone therapy in one trial. Radiation may be delayed in order to preserve marrow reserve for aggressive systemic therapy. Outcomes appear better for patients with overt disease after completion of therapy than for patients with overt disease while still on therapy. However, no advantage could be shown for early diagnosis and 25 of 839 boys with negative initial biopsies had subsequent testicular relapse. With continued improvements in tissue typing, management of acute graft-versus-host disease and other supportive care measures, the outcomes of such alternative donor transplants now approximate those from matched related donors. Even in aggregate, small series may not be representative of the total experience. Small numbers quickly erode statistical power and obscure possibly important differences. Various statistical techniques can adjust for waiting-time bias but selection bias proves more challenging; therefore, an intent-to-treat analysis is the least biased. The superiority of a particular transplant regimen over a particular chemotherapy regimen does not imply that the same or a second transplant regimen will necessarily be superior to a second chemotherapy regimen. Estimated 3-year progression-free survival was significantly better in the mitoxantrone group (64. The impact of parenteral methotrexate and intrathecal chemotherapy and other agents such as corticosteroids has been somewhat challenging to define. Factors such as the assessment tools used, heterogeneity in populations tested and the treatment regimens delivered, differences in time points during treatment when testing was undertaken, also contribute to the complexity in defining the risk, and furthermore, the clinical impact of numerical differences in test scores can be difficult to define. Comparisons of neurocognitive outcomes in children treated with regimens containing cranial irradiation versus chemotherapy alone have generally suggested better outcomes when radiation is omitted289,294,295,296 but not all studies have shown a significant difference. Modest activity in phase I trials; likely synergistic with other agents Signal transduction inhibitors; induce cell-cycle arrest so that cells may be less susceptible to cell-cycle specific agents this study. Prospective longitudinal studies of large numbers of children who receive contemporary chemotherapy regimens will be helpful in further defining risk factors for adverse neurologic sequelae and the natural history of deficits over time. Adolescent age (10 to 20 years) and exposure to dexamethasone have been shown to be some of the greatest risk factors for this complication. These include impairment in growth, thyroid function, gonadal function, bone health, and adrenal function. Coronal (A) and sagittal (B) T2 images from a magnetic resonance imaging scan demonstrating corticosteroid-inducted avascular necrosis of the right medial femoral condyle in a 15-year-old white girl. Prognostic risk stratification is shifting from clinical factors to a combination of clinical, immunophenotype, and molecular genetic data. Early identification of minimal residual disease is also now incorporated into therapeutic strategies. Novel agents that are directed at molecular targets are under investigation to improve outcomes. Differing complications of hyperleukocytosis in children with acute lymphoblastic or acute nonlymphoblastic leukemia. Augmented post-induction therapy for children with high-risk acute lymphoblastic leukemia and a slow response to initial therapy. Long-term follow-up of the United Kingdom medical research council protocols for childhood acute lymphoblastic leukaemia, 1980­2001. Long-term results of Dutch Childhood Oncology Group studies for children with acute lymphoblastic leukemia from 1984 to 2004. Dexamethasone versus prednisone for induction therapy in childhood acute lymphoblastic leukemia: a systematic review and meta-analysis. Systematic review and meta-analysis of randomized trials of central nervous system directed therapy for childhood acute lymphoblastic leukemia. Long-term results of St Jude Total Therapy Studies 11, 12, 13A, 13B, and 14 for childhood acute lymphoblastic leukemia. Long-term results of a randomized trial on extended use of high dose L-asparaginase for standard risk childhood acute lymphoblastic leukemia. L-asparaginase for treatment of childhood acute lymphoblastic leukemia: what have we learned Toxicity and efficacy of 6-thioguanine versus 6-mercaptopurine in childhood lymphoblastic leukaemia: a randomised trial. Feasibility study of preemptive withdrawal of immunosuppression based on chimerism testing in children undergoing myeloablative allogeneic transplantation for hematologic malignancies. Phase 2 trial of clofarabine in combination with etoposide and cyclophosphamide in pediatric patients with refractory or relapsed acute lymphoblastic leukemia. Twenty-five-year follow-up among survivors of childhood acute lymphoblastic leukemia: a report from the Childhood Cancer Survivor Study. Comparison of long-term neurocognitive outcomes in young children with acute lymphoblastic leukemia treated with cranial radiation or high-dose or very high-dose intravenous methotrexate. Attention and working memory abilities in children treated for acute lymphoblastic leukemia. Cognitive outcomes following contemporary treatment without cranial irradiation for childhood acute lymphoblastic leukemia. Low incidence of second neoplasms among children diagnosed with acute lymphoblastic leukemia after 1983. Cumulative incidence of secondary neoplasms as a first event after childhood acute lymphoblastic leukemia. Pharmacokinetic, pharmacodynamic, and pharmacogenetic determinants of osteonecrosis in children with acute lymphoblastic leukemia. Cardiotoxicity in childhood cancer survivors: strategies for prevention and management. Glucocorticoids and insulin resistance in children with acute lymphoblastic leukemia. Meta-analysis of randomised trials comparing thiopurines in childhood acute lymphoblastic leukaemia. Systematic review of the addition of vincristine plus steroid pulses in maintenance treatment for childhood acute lymphoblastic leukaemia-an individual patient data meta-analysis involving 5,659 children. Outcome of patients treated for relapsed or refractory acute lymphoblastic leukemia: a therapeutic advances in childhood leukemia consortium study. Unrelated donor stem cell transplantation compared with chemotherapy for children with acute lymphoblastic leukemia in a second remission: a matched-pair analysis. New markers for minimal residual disease detection in acute lymphoblastic leukemia. Prognostic value of genetic alterations in children with first bone marrow relapse of childhood B-cell precursor acute lymphoblastic leukemia. Hematopoietic cell transplantation for children with acute lymphoblastic leukemia in second complete remission: 262. The term myelogenous, or myeloid, derives from the terms myelos, meaning marrow and genesis, meaning birth. The original cases of Virchow and Bennett probably represented what we now know to be either chronic lymphocytic or myelogenous leukemia. The first likely case of acute leukemia was reported by Friedreich and was believed to be lymphocytic. Initially, cases of monocytic leukemia were described, followed by myelomonocytic leukemia. During the mid1800s, Virchow used diet therapies, ferric iodide, and application of abdominal and foot baths. Unfortunately acute leukemia does not respond satisfactorily to any form of treatment. The subsequent introduction of more intensive remission induction regimens and post-remission therapy increased the need for more rigorous supportive care measures, and the development of bone marrow transplantation led to current cure rates of about 50%. Normal hematopoiesis occurs through a series of complex changes that facilitate multipotential hematopoietic stem cells to both expand and differentiate into various mature blood cell types. Thus, myeloid leukemias retain many of the molecular and cellular phenotypic characteristics of their normal hematopoietic origins, providing the means to distinguish subtypes of the disease and define potential leukemic stem cell compartments. The same is true for the expression of differentiation markers that characterize various myeloid lineages such as megakaryoblastic, erythroid, or monocytic. The initiating events may primarily affect the ability of the leukemic stem cell to differentiate but retain the ability to self-replicate. Mutations that do not affect the phenotype may be considered "passenger" mutations. The overall risk of developing leukemia has been estimated to be about 14-fold above that of the general population. The schema shows different pathways and/or approaches that have been or are being tested in clinical trials, including those that may affect the leukemia-initiating cell. Photomicrograph of a peripheral blood smear from a patient with Down syndrome and transient myeloproliferative disease. Mutations in the elastase gene have been associated with both cyclic neutropenias and Kostmann syndrome. The risk for identical twins is high when leukemia first develops during infancy; in most cases, transmission has been shown to be the result of transplacental transfer. Transmission rates have been reported to be 20% to 30%, although other investigators have concluded transmission rates may approach 100%. Molecular studies have demonstrated that identical molecular defects characterized the leukemia in both twins. These normal twins should be followed approximately every 1 to 2 months until approximately 2 years of age with physical examinations and peripheral blood cell counts. Approximately 1012 leukemia cells have been estimated to be present at the time of diagnosis. The leukemic blasts can invade extramedullary sites, such as soft tissues, skin (leukemia cutis), gingiva, orbit, and brain. Patients typically present with signs and symptoms of neutropenia, anemia, and thrombocytopenia. Blood cultures and broad-spectrum intravenous antibiotic coverage are indicated in any newly diagnosed patient with leukemia and fever. Anemia results in fatigue, lethargy, decreased exercise tolerance, headache, and pallor. Gingival hyperplasia and leukemia cutis are less frequent but particularly characteristic of myeloid leukemia with monocytic differentiation. Patients may also present with anemia, which gives rise to fatigue, pallor, and, in extreme cases, hemodynamic instability. Such exposures include petroleum products, benzene, pesticides, and herbicides,123­127 although these studies have not focused on children. Interestingly, in some instances, such as with organophosphate pesticides, children may be at greater risk for accumulating higher levels of the chemicals. On occasion, definitive diagnosis is difficult either because of technical difficulties in obtaining an adequate specimen or because of conflicting data. Touch preparations of the bone marrow biopsy may be used in cases in which bone marrow aspiration is difficult. Generally, both classification systems apply equally well to pediatric and adult patients.

Because of this blood­brain barrier, the extracellular space of the brain represents a special fluid compartment in which the chemical composition is regulated separately from that in the plasma and general body extracellular fluid compartment arthritis medication nhs indomethacin 75 mg online. The blood­brain barrier serves to protect the cerebral cells from ionic disturbances in the plasma because it is not very permeable to charged substances rheumatoid arthritis yellow eyes indomethacin 50 mg buy otc. Also, by exclusion and/or endothelial cell metabolism, it prevents many circulating hormones (and drugs) from influencing the parenchymal cells of the brain and the vascular smooth muscle cells in brain vessels arthritis knee diet treatment buy 75 mg indomethacin overnight delivery. Brain capillaries have a special carrier system for glucose and present no barrier to oxygen and carbon dioxide diffusion is arthritis diet related cheap 75 mg indomethacin amex. Thus, the blood­brain barrier does not restrict nutrient supply to the brain tissue can arthritis in fingers be prevented indomethacin 25 mg purchase online. He is a salesman in a high stress industry, has smoked two packs of cigarettes a day for more than 25 years, and eats a high-fat, high-salt diet. His medical record indicates that he has been treated with sublingual nitroglycerin for mild angina pectoris for several years and had been instructed about lifestyle changes. The angina has been getting more severe and required increasingly more nitroglycerin to achieve relief. He is taken immediately to the cardiac catheterization laboratory and an angiogram reveals an almost complete occlusion of his left anterior descending coronary artery. A stent is placed in the artery and blood flow is restored to the ischemic tissue. The condition experienced by this man occurs whenever coronary blood flow decreases below that required to meet the metabolic needs of the heart. The most common cause of coronary artery disease is atherosclerosis of the large coronary arteries and this man had several of the known risk factors (smoking, obesity, high stress, poor diet, high blood cholesterol). Localized lipid deposits called plaques develop within the arterial walls and with severe disease may become large enough to permanently narrow the lumen of arteries. If the coronary artery narrowing (stenosis) is not too severe, local metabolic vasodilator mechanisms may reduce arteriolar resistance sufficiently to compensate for the abnormally increased coronary arterial resistance. Anginal pain is often absent in individuals with coronary artery disease when they are resting but is induced during physical exertion or emotional excitement when sympathetic activity is increased and myocardial oxygen consumption is elevated. Primary treatment of coronary artery disease includes lifestyle alterations and attempts to lower blood lipids by dietary and pharmacological techniques. Treatment of angina that is a result of coronary artery disease may first involve quick-acting vasodilator drugs such as nitroglycerin to provide relief during an anginal attack. Second, -adrenergic blocking agents such as propranolol may be used to block the effects of cardiac sympathetic nerves on heart rate and contractility. These agents limit myocardial oxygen consumption and prevent it from increasing above the level that the compromised coronary blood flow can sustain. Third, calcium channel blockers such as verapamil may be used to dilate coronary and systemic blood vessels, and to lower blood pressure and heart rate. These drugs, which block entry of calcium into the vascular smooth muscle cell, interfere with normal excitation­contraction coupling. Fluoroscopic techniques combined with radio-opaque contrast injections can be used to visualize the coronary arteries. A balloon-tipped catheter can be threaded into the occluded region of the coronary artery and rapidly inflated to squeeze the plaque against the vessel wall and improve the patency of the vessel. This technique, called coronary angioplasty, may also be effective in opening occlusions produced by intravascular clots associated with acute myocardial infarction. A small, mesh tubular device called a stent is often implanted inside the vessel at the angioplasty site. This rigid implant has been shown to improve continued patency of the vessel over a longer period than angioplasty alone. If angioplasty and stent placement is inappropriate or unsuccessful, coronary bypass surgery may be performed. The stenotic coronary artery segments are bypassed by implanting parallel low-resistance pathways formed from either natural. Sympathetic vasoconstrictor nerves provide the primary reflex mechanisms for regulating both arteriolar and venous tone. Sympathetic vasoconstrictor nerves release norepinephrine, which interacts with 1-adrenergic receptors on vascular smooth muscle to induce vasoconstriction. The relative importance of local metabolic versus reflex sympathetic control of arteriolar tone (and therefore blood flow) varies from organ to organ. In many organs (such as brain, heart muscle, and exercising skeletal muscle), blood flow normally closely follows metabolic rate because of local metabolic influences on arterioles. In other organs (such as skin and kidneys), blood flow is normally regulated more by sympathetic nerves than by local metabolic conditions. Vascular smooth muscle differs from cardiac muscle in that it A) contains no actin molecules. A) decrease total peripheral resistance B) decrease mean arterial pressure C) decrease capillary hydrostatic pressure D) increase transcapillary fluid filtration E) increase blood flow through the capillary bed 3. When an organ responds to an increase in metabolic activity with a decrease in arteriolar resistance, this is known as A) active hyperemia. A particular vascular bed demonstrates the phenomenon of autoregulation of blood flow. Vascular smooth muscle has many properties that make it sensitive to a wide array of local and reflex stimuli and capable of maintaining tone for long periods of time. The tone of arterioles, but not veins, can be strongly influenced by local vasodilator factors produced by local tissue metabolism. Define mean circulatory filling pressure and state the primary factors that determine it. Describe the relationship between central venous pressure and venous return and draw the normal venous return curve. Predict the shifts in the venous return curve that occur with altered blood volume and altered venous tone. Describe how the output of the left heart pump is matched to that of the right heart pump. Draw the normal venous return and cardiac output curves on a graph and describe the significance of the point of curve intersection. Predict how normal venous return, cardiac output, and central venous pressure will be altered with any given combination of changes in cardiac sympathetic tone, peripheral venous sympathetic tone, or circulating blood volume. Identify conditions that may result in abnormally high or low central venous pressure. Each of the segments of this circuit has a distinctly different role to play in the overall operation of the system because of inherent differences in anatomical volume, resistance to blood flow, and compliance that are summarized in Table 28­1. This value indicates how sensitive the ventricular end-diastolic volume (and therefore stroke volume and cardiac output) is to small changes in cardiac filling pressure. Cardiac filling pressure is a crucial factor that determines how well the cardiovascular system functions. It will take a certain amount of blood just to fill the anatomical space contained by the systemic system without stretching any of its walls or developing any internal pressure. From the total systemic circuit compliance (C) given in Table 28­1, one can see that an extra 1,000 mL of blood would result in an internal pressure of about 7 mm Hg. This theoretical pressure is called the mean circulatory filling pressure and is the pressure that would exist throughout the system in the absence of flow. The two major factors that affect mean circulatory filling pressure are the circulating blood volume and the state of the peripheral venous vessel tone. V0, anatomical volume of compartment at zero pressure: C, compliance of compartment; R, resistance to flow through compartment. New York: Lange Medical Books/ Great veins in thorax and right atrium McGraw-Hill, 2006. The other major components of the system (arteries and capillaries) do not actively change their contained volume. This causes pressures on the arterial side to increase above the mean circulatory pressure while pressures on the venous side decrease below it. Because veins are about 50 times more compliant than arteries (Table 28­1), the flow-induced decrease in venous pressure is only about 1/50th as large as the accompanying increase in arterial pressure. Because the cardiovascular system is a closed hydraulic loop, adjustments in any one part of the circuit will have pressure, flow, and volume effects throughout the circuit. Because of the critical influence of cardiac filling on cardiovascular function, the remainder of this chapter will focus on the factors that determine the pressure in the central venous compartment. In addition, the way in which measures of central venous pressure can provide clinically useful information about the state of the circulatory system will be discussed. The central venous compartment corresponds roughly to the volume enclosed by the right atrium and the great veins in the thorax. Blood leaves the central venous compartment by entering the right ventricle at a rate that is equal to the cardiac output. Venous return, in contrast, is the rate at which blood returns to the thorax from the peripheral vascular beds and thus is the rate at which blood enters the central venous compartment. In any stable situation, venous return must equal cardiac output or blood would gradually accumulate in either the central venous compartment or the peripheral vasculature. However, there often are temporary differences between cardiac output and venous return. Because the central venous compartment is enclosed by elastic tissues, any change in central venous volume produces a change in central venous pressure. As explained below, central venous pressure has an equally important negative effect on venous return. Thus, central venous pressure is always automatically driven to a value that makes cardiac output equal to venous return. Thus, "peripheral venous pressure" can be viewed as essentially equivalent to "mean circulatory filling pressure. If the peripheral venous pressure remains at 7 mm Hg, decreasing central venous pressure will increase the pressure difference across the venous pathway and consequently cause an increase in venous return to the central venous pool. This relationship is summarized by the venous function curve, which shows how venous return increases as central venous pressure decreases. There are two minor additional points to be made about this venous function curve. Second, if central venous pressure reaches very low values and decreases below the intrathoracic pressure, the veins in the thorax collapse and tend to limit venous return. Just as a cardiac function curve shows how central venous pressure influences cardiac output, a venous function curve shows how central venous pressure influences venous return. Therefore, an increase in peripheral venous pressure can be just as effective in increasing venous return as a decrease in central venous pressure. The two ways in which peripheral venous pressure can change were discussed in Chapter 26. Moreover, because the veins are much more compliant than any other vascular segment, changes in circulating blood volume produce larger changes in the volume of blood in the veins than in any other vascular segment. For example, blood loss by hemorrhage or loss of body fluids through severe sweating, vomiting, or diarrhea will decrease circulating blood volume and significantly reduce the volume of blood contained in the veins and thus decrease the peripheral venous pressure. Conversely, transfusion, fluid retention by the kidney, or transcapillary fluid reabsorption will increase circulating blood volume and venous blood volume. Recall from Chapter 27 that the second way that peripheral venous pressure can be altered is through changes in venous tone produced by increasing or decreasing the activity of sympathetic vasoconstrictor nerves supplying the venous smooth muscle. In addition, an increase in any force compressing veins from the outside has the same effect on the pressure inside veins as an increase in venous tone. Thus, such things as muscle exercise and wearing elastic stockings tend to increase peripheral venous pressure. Whenever peripheral venous pressure is altered, the relationship between central venous pressure and venous return is also altered. When peripheral venous pressure is 7 mm Hg, venous return is 0 L/min when central venous pressure is 7 mm Hg. When peripheral venous pressure is increased to 10 mm Hg, considerable venous return occurs with a central venous pressure of 7 mm Hg, and venous return stops only when central venous pressure is increased to 10 mm Hg. Thus, increasing peripheral venous pressure shifts the whole venous function curve to the right. By similar logic, decreased peripheral venous pressure caused by blood loss or decreased sympathetic vasoconstriction of peripheral veins shifts the venous function curve to the left. In most contexts, however, "cardiac output" implies the output of the left heart pump. How is it then, as has often been previously implied, that central venous pressure (the filling pressure of the right heart) profoundly affects cardiac output (the output of the left heart) The short answer is that in the steady state, the right and left hearts have equal outputs. The major conclusion here is that left atrial pressure will change in the correct direction to match left ventricular stroke volume to the current right ventricular stroke volume. If central venous pressure were to decrease to 0 mm Hg, cardiac output would decrease (to 2 L/min) and venous return would increase (to 7 L/min). With a venous return of 7 L/min and a cardiac output of 2 L/min, the volume of the central venous compartment would necessarily be increasing and this would produce a progressively increasing central venous pressure. Moreover, if central venous pressure were to increase from 2 to 4 mm Hg, venous return would decrease (to 3 L/min) and cardiac output would increase (to 7 L/min). This would quickly reduce the volume of blood in the central venous pool, and the central venous pressure would soon fall back to the original level. The cardiovascular system automatically adjusts to operate at the point where the cardiac and venous function curves intersect. Central venous pressure is always inherently driven to the value that makes cardiac output and venous return equal. Cardiac output and venous return always stabilize at the level where the cardiac function and venous function curves intersect.

The maculae also discharge tonically in the absence of head movement, because of the pull of gravity on the otoliths arthritis worse during period purchase 25 mg indomethacin mastercard. The labyrinth righting reflexes are a series of responses integrated in midbrain nuclei in response to head tilt arthritis of fingers exercises 25 mg indomethacin order. The response is a compensatory contraction of neck muscles to keep the head level arthritis knee numbness discount indomethacin 25 mg overnight delivery. These reflexes stabilize the head and keep the eyes fixed on visual targets despite movements of the body arthritis in fingers cream purchase indomethacin with visa. Vestibular impulses that reach the cerebral cortex are likely responsible for conscious perception of motion and supply part of the information necessary for orientation in space arthritis pain or bone cancer effective 50 mg indomethacin. Vertigo is the sensation of rotation in the absence of actual rotation and is a prominent symptom when one labyrinth is inflamed. An inflammatory response can increase fluid volume within the membranous labyrinth, causing it to rupture and allowing the endolymph and perilymph to mix together. There is no cure for Ménière disease but the symptoms can be controlled by reducing the fluid retention through dietary changes (low-salt or salt-free diet, no caffeine, no alcohol) or medication. During her latest episode, she realized that she could barely hear her daughter calling for her in the next room. In particular, she experienced tinnitus, vertigo, and nausea on various occasions. Because the symptoms occurred only sporadically and lasted for only hours or a day, she did not seek medical advice. She was later seen by an otolaryngologist and a neurologist to rule out other causes of her symptoms. Ménière disease is an abnormality of the inner the external ear funnels sound waves to the external auditory meatus and tympanic membrane. From there, sound waves pass through three auditory ossicles (malleus, incus, and stapes) in the middle ear. The stereocilia provide a mechanism for generating changes in membrane potential proportional to the direction and distance the hair moves. Sound is the sensation produced when longitudinal vibrations of air molecules strike the tympanic membrane. The activity within the auditory pathway passes from the eighth cranial nerve afferent fibers to the dorsal and ventral cochlear nuclei to the inferior colliculi to the thalamic medial geniculate body and then to the auditory cortex. Loudness is correlated with the amplitude of a sound wave and pitch with the frequency. Conductive deafness is due to impaired sound transmission in the external or middle ear and impacts all sound frequencies. Sensorineural deafness is due to loss of cochlear hair cells or to damage to the eighth cranial nerve or central auditory pathways. Rotational acceleration stimulates the crista in the semicircular canal, displacing the endolymph in a direction opposite to the direction of rotation, deforming the cupula and bending the hair cell. The utricle responds to horizontal acceleration and the saccule to vertical acceleration. Acceleration in any direction displaces the otoliths, distorting the hair cell processes and generating neural activity. Spatial orientation is dependent on input from vestibular receptors, visual cues, proprioceptors in joint capsules, and cutaneous touch and pressure receptors. A 40-year-old male, employed as a road construction worker for nearly 20 years, went to his physician to report that he has been having difficulty hearing during normal conversations. A Weber test showed that sound from a vibrating tuning fork was localized to the right ear. Weber test showed that sound from a vibrating tuning fork was louder than normal; Schwabach test showed that bone conduction was better than normal; and Rinne test showed that air conduction did not outlast bone conduction. A) sensorial deafness in both ears B) conduction deafness in both ears C) normal hearing D) both sensorial and conduction deafness E) a possible tumor on the eighth cranial nerve 3. Postrotational nystagmus is caused by continued movement of A) aqueous humor over the ciliary body in the eye. C) endolymph in the semicircular canals, with consequent bending of the cupula and stimulation of hair cells. When the damage to the outer hair cells is greater than the damage to the inner hair cells A) perception of vertical acceleration is disrupted. A) tympanic membrane:manubrium of malleus B) helicotrema:apex of cochlea C) foot plate of stapes:oval window D) otoliths:semicircular canals E) basilar membrane:organ of Corti 6. The direction of nystagmus is vertical when a subject is rotated A) after warm water is put in one ear. In the utricle, tip links in hair cells are involved in A) formation of perilymph. New olfactory sensory neurons are generated by basal stem cells as needed to replace those damaged by exposure to the environment. The olfactory bulbs also contain periglomerular cells, which are inhibitory neurons connecting one glomerulus to another, and granule cells, which have no axons and make reciprocal synapses with the lateral dendrites of the mitral and tufted cells. Outline the pathway by which impulses generated in the olfactory epithelium reach the olfactory cortex. Outline the pathways by which impulses generated in taste receptors reach the insular cortex. Physiologically, they are related to each other; the flavors of various foods are in large part a combination of their taste and smell. This explains why food may taste "different" if one has a cold that depresses the sense of smell. Both smell and taste receptors are chemoreceptors that are stimulated by molecules in solution in mucus in the nose and saliva in the mouth. The olfactory epithelium is the place in the body where the nervous system is closest to the external world. These neurons project axons to the olfactory bulb of the brain, a small ovoid structure that rests on the cribriform plate of the ethmoid bone. Conscious discrimination of odors relies on the pathway to the orbitofrontal cortex. The orbitofrontal activation is generally greater on the right side than the left; thus, cortical representation of olfaction is asymmetric. The pathway to the amygdala is involved with the emotional responses to olfactory stimuli, and the pathway to the entorhinal cortex is concerned with olfactory memories. There are three cell types: olfactory sensory neurons, supporting cells, and basal stem cells at the base of the epithelium. Odorants bind to specific odorant receptors on the cilia and initiate a cascade of events leading to generation of action potentials in the sensory axon. Information is transmitted from the olfactory bulb by axons of mitral and tufted relay neurons in the lateral olfactory tract. Mitral cells project to five regions of the olfactory cortex: anterior olfactory nucleus, olfactory tubercle, piriform cortex, and parts of the amygdala and entorhinal cortex. Tufted cells project to anterior olfactory nucleus and olfactory tubercle; mitral cells in the accessory olfactory bulb project only to the amygdala. Conscious discrimination of odor depends on the neocortex (orbitofrontal and frontal cortices). Emotive aspects of olfaction derive from limbic projections (amygdala and hypothalamus). In rodents and some mammals, a well-developed vomeronasal organ is concerned with perception of odors that act as pheromones; its receptors project to the accessory olfactory bulb. The mucus bathes the odorant receptors on the cilia and provides the appropriate molecular and ionic environment for odor detection. Odor-producing molecules are usually small, containing from 3 to 20 carbon atoms, and molecules with the same number of carbon atoms but different structural configurations have different odors. Relatively high water and lipid solubility are characteristic of substances with strong odors. Anosmia (inability to smell) and hyposmia or hypesthesia (diminished olfactory sensitivity) can result from simple nasal congestion or from damage to the olfactory nerves due to fractures of the cribriform plate, neuroblastomas or meningiomas, or infections (such as abscesses). Aging is also associated with abnormalities in smell sensation; more than 75% of humans over the age of 80 have an impaired ability to identify odors. The genes that code for about 1,000 different types of odorant receptors make up the largest gene family so far described in mammals. The amino acid sequences of odorant receptors are diverse, but all the odorant receptors are coupled to heterotrimeric G proteins. This produces the graded receptor potential, which then leads to an action potential in the olfactory nerve. Although there are millions of olfactory sensory neurons, each expresses only 1 of the 1,000 different odorant receptors. This provides a distinct two-dimensional map in the olfactory bulb that is unique to the odorant. The mitral cells with their glomeruli project to different parts of the olfactory cortex. The olfactory glomeruli demonstrate lateral inhibition mediated by periglomerular and granule cells. In addition, the extracellular field potential in each glomerulus oscillates, and the granule cells can regulate the frequency of the oscillation. The exact function of the oscillation is unknown, but it may also help to focus the olfactory signals reaching the cortex. Olfactory receptors are G protein­coupled receptors that dissociate on binding to the odorant. The apical ends of taste cells have microvilli that project into the taste pore, a small opening on the dorsal surface of the tongue where taste cells are exposed to the oral contents. Each taste bud is innervated by about 50 nerve fibers, and conversely, each nerve fiber receives input from an average of five taste buds. They differentiate into new taste cells, and the old cells are replaced with a half-time of about 10 days. If the sensory nerve is cut, the taste buds it innervates degenerate and eventually disappear. Each fungiform papilla has up to 5 taste buds, mostly located at the top of the papilla; each vallate and foliate papilla contains up to 100 taste buds, mostly located along the sides of the papillae. From there, axons of second-order neurons ascend in the ipsilateral medial lemniscus to pass directly to the ventral posteromedial nucleus of the thalamus, from which fibers project to the anterior insula and frontal operculum in the ipsilateral cerebral cortex. This region is rostral to the face area of the postcentral gyrus, which may be the area that mediates conscious perception of taste and taste discrimination. A protein that binds taste-producing molecules is produced by the Ebner gland that secretes mucus into the cleft around vallate papillae. Ageusia (absence of the sense of taste) and hypogeusia (diminished taste sensitivity) can be caused by damage to the lingual or glossopharyngeal nerve. A) Taste buds on the anterior two thirds of the tongue are innervated by the chorda tympani branch of the facial nerve; those on the posterior one third of the tongue are innervated by the lingual branch of the glossopharyngeal nerve. B) the three major types of papillae (circumvallate, foliate, and fungiform) are located on specific parts of the tongue. C) Taste buds are composed of basal stem cells and three types of taste cells (dark, light, and intermediate). Taste cells extend from the base of the taste bud to the taste pore, where microvilli contact tastants dissolved in saliva and mucus. Dysgeusia or parageusia (unpleasant perception of taste) causes a metallic, salty, foul, or rancid taste. The entry of Na+ into the salt receptors depolarizes the membrane, generating the receptor potential. In humans, the amiloride sensitivity of salt taste is less pronounced than in some species, suggesting that there are additional mechanisms to activate salt-sensitive receptors. A hyperpolarization-activated cyclic nucleotide­gated cation channel, and other mechanisms may contribute to sour transduction. The T1R3 family of G protein­coupled receptors is expressed by about 20% of taste cells, some of which also express gustducin. Sugars taste sweet, but so do compounds such as saccharin that have an entirely different structure. Natural sugars such as sucrose and synthetic sweeteners may act via different receptors on gustducin. Like the bitter-responsive receptors, sweet-responsive receptors act via cyclic nucleotides and inositol phosphate metabolism. Many G protein­linked receptors in the human genome are taste receptors (T2R family) and are stimulated by bitter substances such as strychnine. Some bitter compounds are membrane permeable and may not involve G proteins; quinine is an example. Umami taste is due to activation of a truncated metabotropic glutamate receptor, mGluR4, in the taste buds. Glutamate in food may also activate ionotropic glutamate receptors to depolarize umami receptors. Signals from the taste buds travel via different nerves to gustatory areas of the nucleus of the tractus solitarius that relays information to the thalamus; the thalamus projects to the gustatory cortex N. An x-ray showed that he had broken his ethmoid bone that separates the nasal cavity from the brain. Following this accident, he lost the sense of smell (anosmia), and his sense of taste was also diminished. The nerve can be damaged when the bone is broken, resulting in the loss of the ability to smell. Because of the close relationship between taste and smell, anosmia is associated with a reduction in taste sensitivity (hypogeusia).

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