By Z. Surus. Texas Chiropractic College. 2018.
In some the professional license is reinstated proventil 100mcg overnight delivery asthma treatment mask, there instances discount 100mcg proventil free shipping asthma symptoms heart, the stress and tension imposed may be a probationary period in which by the job may be beyond individuals’ tol- individuals’ work performance is closely erance and coping ability. Although Case Studies 227 decisions may be made on a case-by-case addiction, which by then had gone on to basis, such charges and their impact on include heroin. She has been in and out employment in different ﬁelds and in dif- of treatment for the past 10 years, and she ferent locations must be considered. As has been drug-free since she became preg- with most disabilities, the attitudes and nant with her son; however, during her concerns of employers must be addressed, drug use she also developed hepatitis C, especially since social stigma is often which is currently in remission. Em- been uneasy about returning to work but ployers may require particular encourage- knows she needs to support her son. Her ment to reinstate or hire individuals who parents live nearby and have offered to have been convicted of criminal charges. How does the diagnosis of hepatitis increasing awareness of substance abuse C affect Ms. What social factors are important to er, individuals may encounter decreasing consider when helping Ms. He com- pleted high school and obtained a job as Case I a yard laborer at a railroad. Her use continued after col- responsibility was to move cars within the lege and intensiﬁed after she obtained a yard, where they were then repaired. She alcohol use did not interfere with his work lost her job after 2 years because of her performance initially, although he drank 228 CHAPTER 7 CONDITIONS RELATED TO SUBSTANCE USE heavily after work every day and was a Questions binge drinker with his wife on days off. What ramiﬁcations does the diagno- 3 months in a residential treatment facil- sis of Wernicke’s encephalopathy ity, where he was treated for Wernicke’s have for Mr. Treatment of heroin (diamorphine) addiction: Rehabilitation Education, 15(2), 155–165. Substance abuse among clients with other primary disabilities: Curricular implications for rehabilita- American Psychiatric Association. Rehabilitation Education, 4(1), and statistical manual of mental disorders (4th ed. Marijuana abstinence effects in mar- seeking as a predictor of treatment retention for ijuana smokers maintained in their home environ- heroin dependent cocaine users. Smoking topography and carbon monox- ences in the biphasic effects of ethanol. Addictive Behavior, 10, Alcoholism, Clinical and Experimental Research, 22, 319–323. Substance and shadow: Women England Journal of Medicine, 349(10), 975–986. Ofﬁce-based treatment of of methamphetamine with implications for prevention, opiate addiction with a sublingual-tablet formu- treatment, and research. New Mental Health Services Administration and Center England Journal of Medicine, 349(10), 949–958. Caffeine consumption and disability: Clinical The role of corticotrophin-releasing factor in drug issues in rehabilitation. New England Journal of Behavioral Health Services and Research, Journal of Medicine, 343(18), 1332–1333. Drug abuse and mental illness: Screening instruments for alcohol and other drug Progress in understanding comorbidity. Journal of Mental Health Counseling, Journal of Psychiatry, 158(8), 1181–1183. C HAPTER 8 Conditions of the Blood and Immune System NORMAL STRUCTURE AND contained within the blood are red blood FUNCTION cells (erythrocytes), white blood cells (leu- kocytes), and platelets (thrombocytes). Blood is a combination of different More than 99 percent of the cells in blood types of cells and liquid that circulates are red blood cells. The The number of circulating white blood quantity of blood in the adult body cells under normal circumstances is min- remains constant under normal condi- imal. Blood cells are produced in the bone stimuli are present, white blood cells pro- marrow, as well as in lymphoid tissue and liferate so that there are large numbers of organs. The number of platelets circulating in Blood has many important functions: the blood normally does not change.
Ciguatera toxin order proventil 100mcg amex asthma treatment by fish in hyderabad 2016, the product of a dinofla- constant spans the two synapses; therefore generic 100 mcg proventil with amex asthma night cough, properties gellate that sometimes contaminates red snapper and of the cell that increase the space constant would opti- other reef fishes, is probably the cause of the sensory mize the effectiveness of the two synapses. Ciguatera constant increases with increasing membrane resist- toxin binds to voltage-gated sodium channels and re- ance or decreasing cytoplasmic resistance. Temporal summation could also increase the conduction velocity because the action potential will effectiveness of the two synapses; this would be facili- no longer “jump” from node to node. Acetylcholinesterase is the enzyme tentials) will be more spread out and will have a slower that breaks acetylcholine down into acetate and rate of rise than normal. Blocking the function of opening of voltage-gated calcium channels and entry acetylcholinesterase would prevent the breakdown of of extracellular calcium into the nerve terminals. Defi- ACh, which would accumulate in the cleft because cient acetylcholine release by motor nerve terminals there is no uptake mechanism for ACh and it diffuses could explain muscle weakness. Catecholaminergic transmission is ef- polarization phase of the nerve action potential de- ficient, in part, because there is a significant reuptake pends on voltage-gated potassium channels. The of the catecholamines for repackaging into synaptic upstroke of the nerve action potential depends on volt- vesicles to use again. Nerve excitability (and, in the cleft and do not aid in the removal of the cate- hence, nerve firing) is affected by extracellular calcium cholamines from the cleft. The postsynaptic cell may concentration (hypocalcemia results in increased ex- have an uptake mechanism (not endocytosis) for the citability), but this is because of an effect on sodium catecholamines, but the efficacy of this mechanism is channels, not calcium channels. Dopamine plays a major role in two Chapter 4 functional systems of the brain, the motor system and the limbic system. Too much dopaminergic trans- is encoded in the action potential frequency. Cessation mission can result in psychotic disorders, such as schiz- of the stimulus would lead to a rapid decrease in the ac- ophrenia. A blockade of dopaminergic transmission tion potential frequency, and adaptation of the recep- ameliorates psychosis. Cholinergic transmission is in- tor would also lead to a decrease in frequency. The constant and maintained stimulus, at least some adap- role of nitrergic transmission in cognition and behav- tation would take place, and the frequency would fall ior is unknown. Most neurotransmitters are synthe- tential velocity is a property of the nerve—not the re- sized locally within the axon terminals from precursors ceptor—and it would not be affected. Rods and cones are absent from the tended limb are best sensed by receptors that adapt area of the retina where the optic nerve exits. Likewise, sensors that adapt quickly would not blind spot is of appreciable size, but because its loca- be well suited for detecting the continued presence of tion is off-center and the eyeballs are mirror images, a chemical stimulus. Reduction in the intensity of a sensa- cause nerves are exiting there and do not make tion is largely the result of a decline in the generator synapses. Presbyopia is the age-related inabil- duction in the stimulus intensity. The decreased potentials arising in a sensory nerve are all-or-none, compliance of the lens prevents it from assuming a suf- their velocity of conduction, amplitude, and duration ficiently curved state, and the focal point is behind the of depolarization are not affected by the stimulus in- retina. As a person ages, only minor changes occur in tensity; rather, they are properties of the nerve cell. The transfer of energy through the opacity of structures through which light must pass, middle ear from the relatively large eardrum to the while they can impair vision, have little effect on the smaller oval window by the ossicular chain increases the focal point of the light rays. A myopic eyeball is too long, and bones do not support the membrane structures but allow light rays coming from great distances focus in front of them to move relatively freely. The range of motion available to the lens is sicular transmission process by external influences (as by not sufficient to provide accommodation regardless of the stapedius and tensor tympani muscles) or by disease the effort made. A negative lens placed in front of the processes, acts to reduce the vibration transfer effi- eye corrects the eye’s refractive power, and the rays ciency, a change that can be either protective or harm- will now focus on the retina. The function of the eustachian tube is independent worsen matters, and a cylindrical lens (which has two of the ossicles. While the bones themselves are passive, foci, depending on the orientation considered) would they are essential to the process of sound conduction. The cone cells, which are responsible tensity also would not help; the pupils would dilate and for color vision, are located at the point of sharpest fo- admit more peripheral rays that would be further out of cus, but they do not function if the light intensity too focus. The frequency response of the basi- greater sensitivity, but with less advantageous location lar membrane changes steadily from high to low along and interconnection) provide monochromatic but dif- its length, so that high frequencies are detected close fuse vision. The color composition of light does not to the oval window and low frequencies are detected at depend on its intensity, and dark adaptation does not the other end, near the helicotrema.
The rently unknown although both Sertoli and Leydig cells tight junctions limit the transport of fluid and macromole- have been implicated in its secretion discount 100mcg proventil asthma breathing. Thus buy cheap proventil 100 mcg online asthma 3 month old baby, the deactivation of activin by binding to follis- germ cells at various stages of division and differentiation. Follistatin is apparently Mitosis of the spermatogonia (diploid progenitors of sper- produced by Sertoli cells and acts as a paracrine factor on matozoa) occurs in the basal compartment of the seminifer- the developing spermatogenic cells. The early meiotic cells (primary spermatocytes) move across the junctional complexes into the adluminal compartment, where they mature into sper- matozoa or gametes after meiosis. The adluminal compart- THE MALE REPRODUCTIVE ORGANS ment is an immunologically privileged site. Spermatozoa The testes produce spermatozoa and transport them that develop in the adluminal compartment are not recog- through a series of ducts in preparation for fertilization. Consequently, males The testes also produce testosterone that regulates devel- can develop antibodies against their own sperm, resulting in opment of the male gametes, male sex characteristics, and infertility. Sperm antibodies are often present after vasec- CHAPTER 37 The Male Reproductive System 653 Spermatogonium Spermatozoon Lumen Sertoli cell Basement membrane Leydig cell surrounding the seminiferous tubule The testis. Receptors for FSH, present only where the adluminal compartment is ruptured, allowing on the plasma membranes of Sertoli cells, are glycoproteins sperm to mingle with immune cells from the circulation. FSH exerts mul- tiple effects on the Sertoli cell, most of which are mediated by cAMP and protein kinase A (Fig. FSH stimulates Sertoli Cells Have Multiple Functions the production of androgen-binding protein and plasmino- Sertoli cells are critical to germ cell development, as indi- gen activator, increases secretion of inhibin, and induces cated by their close contact. As many as 6 to 12 spermatids aromatase activity for the conversion of androgens to es- may be attached to a Sertoli cell. The testosterone receptor is within the nucleus of residual bodies (excess cytoplasm resulting from the trans- the Sertoli cell. It is sim- nal detachment of mature spermatozoa from the Sertoli cell ilar in function, with some homology in structure, to an- into the lumen. Spermiation may involve plasminogen ac- other binding protein, sex hormone-binding globulin tivator, which converts plasminogen to plasmin, a prote- (SHBG), synthesized in the liver. ABP is found at high con- olytic enzyme that assists in the release of the mature sperm centrations in the human testes and epididymis. Sertoli cells also synthesize large amounts a carrier of testosterone in Sertoli cells, as a storage protein of transferrin, an iron-transport protein important for for androgens in the seminiferous tubules, and as a carrier sperm development. During the fetal period, Sertoli cells and gonocytes form Other products of the Sertoli cell are inhibin, follistatin, the seminiferous tubules as Sertoli cells undergo numerous and activin. The pituitary gonadotrophs and testic- cease proliferating, and throughout life, the number of ular Sertoli cells form a classical negative-feedback loop in sperm produced is directly related to the number of Sertoli which FSH stimulates inhibin secretion and inhibin sup- cells. At puberty, the capacity of Sertoli cells to bind FSH presses FSH release. Inhibin also functions as a paracrine 654 PART X REPRODUCTIVE PHYSIOLOGY agent in the testes. Follistatin, an activin-binding protein, reduces FSH secre- Leydig cell tion induced by activin. Basement membrane surrounding seminiferous tubule Leydig Cells Produce Testosterone Spermatogonium Leydig cells are large polyhedral cells that are often found in clusters near blood vessels in the interstitium between Basal compartment seminiferous tubules. They are equipped to produce Tight junction steroids because they have numerous mitochondria, a Adluminal compartment prominent smooth ER, and conspicuous lipid droplets. Spermatocyte Leydig cells undergo significant changes in quantity and activity throughout life. This mechanism may depend on a nuclear transcription factor, steroidogenic factor-1 (SF-1), that recognizes a sequence in the promoter of all genes en- Spermatid Nucleus coding CYP enzymes. In the human fetus, the period from weeks 8 to 18 is marked by active steroidogenesis, which is Nucleus obligatory for differentiation of the male genital ducts. Ley- dig cells at this time are prominent and very active, reach- Intercellular space ing their maximal steroidogenic activity at about 14 weeks, when they constitute more than 50% of the testicular vol- Spermatozoon ume. Because the fetal hypothalamic-pituitary axis is still underdeveloped, steroidogenesis is controlled by human chorionic gonadotropin (hCG) from the placenta, rather Sertoli cell Sertoli cell than by LH from the fetal pituitary (see Chapter 39); LH and hCG bind the same receptor.
Aldosterone Progesterone may also undergo 17 -hydroxylation in 17 -hydroxylation in these cells discount proventil 100mcg without prescription peep 0 asthma, and cortisol and adrenal the zona fasciculata and zona reticularis generic 100 mcg proventil otc asthma definition webmd. Instead, the enzy- verted to either cortisol or the adrenal androgen an- matic pathway leading to the formation of aldosterone is drostenedione. Pregnenolone is converted by en- The 17 -hydroxylase is not present in cells of the zona zymes in the endoplasmic reticulum to progesterone and glomerulosa; therefore, pregnenolone does not undergo 11-deoxycorticosterone. The latter compound then moves CHAPTER 34 The Adrenal Gland 613 into the mitochondrion, where it is converted to aldos- adrenal glands by microorganisms or autoimmune disease. This conversion involves three steps: the hydroxy- This disorder is called Addison’s disease. If sufficient adrenal lation of carbon 11 to form corticosterone, the hydroxyla- cortical tissue is lost, the resulting decrease in aldosterone tion of carbon 18 to form 18-hydroxycorticosterone, and production can lead to vascular collapse and death, unless the oxidation of the 18-hydroxymethyl group to form al- hormone therapy is given (see Clinical Focus Box 34. In humans, these three reactions are catalyzed by a single enzyme, aldosterone synthase (CYP11B2), an Transport of Adrenal Steroids in Blood. As noted earlier, isozyme of 11 -hydroxylase (CYP11B1), expressed only in steroid hormones are not stored to any extent by cells of the glomerulosa cells. The 11 -hydroxylase enzyme, which is adrenal cortex but are continually synthesized and secreted. The alyze all three reactions involved in the conversion of 11- process by which steroid hormones are secreted is not well deoxycorticosterone to aldosterone; therefore, aldosterone studied. It has been assumed that the accumulation of the fi- is not synthesized in the zona fasciculata and zona reticu- nal products of the steroidogenic pathways creates a con- laris of the adrenal cortex. This gradient is thought to be the driving force for Genetic Defects in Adrenal Steroidogenesis. Inherited diffusion of the lipid-soluble steroids through cellular mem- genetic defects can cause relative or absolute deficiencies in branes and into the circulation. The immediate consequences of these defects bloodstream become bound noncovalently to certain are changes in the types and amounts of steroid hormones plasma proteins. Most of the genetic defects affecting the steroidogenic CBG binds glucocorticoids and aldosterone, but has a enzymes impair the formation of cortisol. Serum albumin also Chapter 32, a drop in cortisol concentration in the blood binds steroid molecules. Albumin has a high capacity for stimulates the secretion of adrenocorticotropic hormone binding steroids, but its interaction with steroids is weak. The consequent rise in The binding of a steroid hormone to a circulating protein ACTH in the blood exerts a trophic (growth-promoting) molecule prevents it from being taken up by cells or being effect on the adrenal cortex, resulting in adrenal hypertro- excreted in the urine. Because of this mechanism, individuals with genetic Circulating steroid hormone molecules not bound to defects affecting adrenal steroidogenesis usually have hy- plasma proteins are free to interact with receptors on cells pertrophied adrenal glands. These diseases are collectively and, therefore, are cleared from the blood. Because of cholesterol side-chain cleavage enzyme, 17 -hydroxylase, this process, adrenal steroid hormones have long half-lives 3 -hydroxysteroid dehydrogenase, 21-hydroxylase, 11 - in the body, ranging from many minutes to hours. The most common defect involves mutations in the gene for 21-hydroxylase Metabolism of Adrenal Steroids in the Liver. The gene for 21-hydroxy- steroid hormones are eliminated from the body primarily lase may be deleted entirely, or mutant genes may code for by excretion in the urine after they have been structurally forms of 21-hydroxylase with impaired enzyme activity. Although many cells are capable of droxylase in the adrenal cortex interferes with the forma- carrying out these modifications, they primarily occur in tion of cortisol, corticosterone, and aldosterone, all of the liver. Because of the re- The most common structural modifications made in ad- duction of cortisol (and corticosterone) secretion in these renal steroids involve reduction of the double bond in ring individuals, ACTH secretion is stimulated. This, in turn, A and conjugation of the resultant hydroxyl group formed causes hypertrophy of the adrenal glands and stimulates the on carbon 3 with glucuronic acid. Corti- ulus causes pregnenolone to be converted to adrenal an- sol, and other 21-carbon steroids with a 17 -hydroxyl drogens in inappropriately high amounts. Thus, women af- group and a 20-keto group, may undergo lysis of the carbon flicted with 21-hydroxylase deficiency exhibit virilization 20–21 side chain as well. The resultant metabolite, with a from the masculinizing effects of excessive adrenal andro- keto group on carbon 17, appears as one of the 17-ketos- gen secretion. Adrenal androgens are also 17-ketos- production can lead to sodium depletion, dehydration, vas- teroids. They are usually conjugated with sulfuric acid or cular collapse, and death, if appropriate hormone therapy is glucuronic acid before being excreted and normally com- not given. Before the development of specific methods to measure androgens Addison’s Disease.
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