By P. Pyran. California College of the Arts. 2018.
It is known that G of the compartment estrogen receptor proteins and adenylyl cyclase (E) The compartment must be in (B) Stimulates the activation of the IP3 normally mediate the stimulation of equilibrium with its surroundings receptor in the sarcoplasmic reticulum growth hormone secretion produced 2 order female viagra 100mg amex. A 62-year-old woman eats a high to increase intracellular calcium by growth hormone-releasing carbohydrate meal order female viagra 100 mg on line. Which of the concentration rises, and this results in tyrosine residues in the cytoplasmic following problems is most likely to increased insulin secretion from the domain of the receptor be present in the patient’s tumor pancreatic islet cells. A single cell within a culture of freshly (E) The cells lack GHRH receptors polycystic kidney disease, epidermal isolated cardiac muscle cells is injected growth factor (EGF) receptors may be with a fluorescent dye that cannot SUGGESTED READING abnormally expressed on the urine side cross cell membranes. Principles of of kidney epithelial cells and may be several adjacent cells become Molecular Regulation. N Engl What type of drug might be useful in (A) Ryanodine receptors J Med 1999;340:1012–1020. Signal Trans- (A) Adenylyl cyclase stimulator (C) Transverse tubules duction. New York: (E) Tyrosine kinase inhibitor generation of inositol trisphosphate Wiley-VCH, 1999. New York: (B) Are always available for signal (A) Are first messengers WH Freeman, 2000. Homeostasis, humpty (C) Always produce the same cellular (C) Can activate tyrosine kinase dumpty, and integrative biology. CHAPTER The Plasma Membrane, Membrane Transport, and the Resting 22 Membrane Potential Stephen A. CHAPTER OUTLINETHE STRUCTURE OF THE PLASMA MEMBRANETHE MOVEMENT OF WATER ACROSS THE PLASMAMECHANISMS OF SOLUTE TRANSPORT MEMBRANETHE RESTING MEMBRANE POTENTIAL KEY CONCEPTS 1. The Na /K -ATPase pump is an example of primary active of a cell are proteins and lipids, present in about equal transport, and Na -coupled glucose transport is an exam- proportions. The polarized organization of epithelial cells produces a di- tions of the plasma membrane, including the transport of rectional movement of solutes and water across the ep- water and solutes across the membrane and providing ithelium. Many cells regulate their volume when exposed to osmotic such as hormones. Carrier-mediated transport systems allow the rapid trans- entry of solute so that water will follow. The Goldman equation gives the value of the mem- strate concentration, exhibit structural specificity, and are brane potential when all the permeable ions are ac- competitively inhibited by molecules of similar structure. In most cells, the resting membrane potential is close to membrane potential, and ligand-gated channels are the Nernst potential for K. Cells must receive nutrients in order to function, and lower inside cells than outside. These differences are nec- they must dispose of metabolic waste products. To function essary for the proper functioning of many intracellular en- in coordination with the rest of the organism, cells receive zymes; for instance, the synthesis of proteins by the ribo- and send information in the form of hormones and neuro- somes requires a relatively high potassium concentration. The plasma membrane has mechanisms that The cell membrane or plasma membrane creates and main- allow specific molecules to cross the barrier around the cell. The ions and cell proteins needed intracellular organelle that requires an internal milieu dif- for normal cell function are prevented from leaking out; ferent from that of the cytosol. The cell nucleus, mito- those not needed by the cell are unable to enter the cell chondria, endoplasmic reticulum, Golgi apparatus, and freely. The cell membrane also keeps metabolic intermedi- lysosomes are delimited by membranes similar in composi- 19 20 PART I CELLULAR PHYSIOLOGY tion to the plasma membrane. This chapter describes the with nonpolar side chains and are arranged in an ordered - specific types of membrane transport mechanisms for ions helical conformation. Peripheral proteins (or extrinsic pro- and other solutes, their relative contributions to the resting teins) do not penetrate the lipid bilayer. They are in con- membrane potential, and how their activities are coordi- tact with the outer side of only one of the lipid nated to achieve directional transport from one side of a layers—either the layer facing the cytoplasm or the layer cell layer to the other. Many membrane proteins have carbohydrate molecules, in the form of spe- cific sugars, attached to the parts of the proteins that are THE STRUCTURE OF THE PLASMA MEMBRANE exposed to the extracellular fluid.
The compromise is to preserve the regulate vascular resistance and thereby interact with car- mean arterial pressure by increasing arterial resistance at the diac output to maintain the arterial blood pressure (see expense of reduced blood flow to most organs other than the Chapter 12) buy female viagra 50 mg overnight delivery. The organs survive this conflict by increas- 262 CHAPTER 16 The Microcirculation and the Lymphatic System 263 ing their extraction of oxygen and nutrients from blood in the microvessels as the blood flow is decreased buy 100mg female viagra visa. The microvasculature is considered to begin where the smallest arteries enter the organs and to end where the smallest veins, the venules, exit the organs. In between are microscopic arteries, the arterioles, and the capillaries. De- pending on an animal’s size, the largest arterioles have an inner diameter of 100 to 400 m, and the largest venules have a diameter of 200 to 800 m. The arterioles divide into progressively smaller vessels to the extent that each section of the tissue has its own specific microvessels. The branching pattern typical of the microvasculature of differ- ent major organs and how it relates to organ function are discussed in Chapter 17. THE ARTERIAL MICROVASCULATURE Large arteries have a low resistance to blood flow and func- tion primarily as conduits (see Chapter 15). As arteries ap- proach the organ they supply, they divide into many small FIGURE 16. In most or- muscle cells wrapping around arterioles of gans, these small arteries, which are 500 to 1,000 m in di- various sizes. Each cell only partially passes around large-diame- ameter, control about 30 to 40% of the total vascular re- ter (1A) and intermediate-diameter (2A) arterioles, but com- sistance. These smallest of arteries, combined with the pletely encircles the smaller arterioles (3A, 4A). The en- blood vessels; together they regulate about 70 to 80% of larged views of 3A and 4A are at 4-times-greater magnification. Constriction of these vessels maintains the rel- testine during maturation. Constriction re- sults from the release of norepinephrine by the sympathetic larger vessel, but may encircle a smaller vessel almost 2 nervous system, from the myogenic mechanism (to be dis- times (see Fig. Vessel Wall Tension and Intravascular Pressure Arterioles Regulate Resistance by the Contraction Interact to Determine Vessel Diameter of Vascular Smooth Muscle The smallest arteries and all arterioles are primarily respon- The vast majority of arterioles, whether large or small, are sible for regulating vascular resistance and blood flow. Ves- tubes of endothelial cells surrounded by a connective tissue sel radius is determined by the transmural pressure gradient basement membrane, a single or double layer of vascular and wall tension, as expressed by Laplace’s law (see Chap- smooth muscle cells, and a thin outer layer of connective ter 14). Changes in wall tension developed by arteriolar tissue cells, nerve axons, and mast cells (Fig. Most arte- cular smooth muscle cells around the arterioles are 70 to 90 rioles can dilate 60 to 100% from their resting diameter and m long when fully relaxed. The muscle cells are anchored can maintain a 40 to 50% constriction for long periods. Vascular smooth muscle cells wrap around the arteri- microscopic blood vessels. For example, a 20-fold increase oles at approximately a 90 angle to the long axis of the ves- in blood flow can occur in contracting skeletal muscle dur- sel. This arrangement is efficient because the tension ing exercise, and blood flow in the same vasculature can be developed by the vascular smooth muscle cell can be al- reduced to 20 to 30% of normal during reflex increases in most totally directed to maintaining or changing vessel di- sympathetic nerve activity. In the majority of organs, arteriolar muscle cells operate at about half their maximal length. If the muscle cells fully relax, the diameter of the vessel can nearly double to in- THE CAPILLARIES crease blood flow dramatically (flow increases as the fourth Exchanges Between Blood and power of the vessel radius; see Chapter 12). When the mus- Tissue Occur in Capillaries cle cells contract, the arterioles constrict, and with intense stimulation, the arterioles can literally shut for brief periods Capillaries provide for most of the exchange between of time. A single muscle cell will not completely encircle a blood and tissue cells. The capillaries are supplied by the 264 PART IV BLOOD AND CARDIOVASCULAR PHYSIOLOGY brane.
Educational interventions Pharmacologic Approaches to are then directed toward correcting these Treatment of Psychiatric Disability deﬁcits buy female viagra 50mg free shipping. Interventions usually begin with Antipsychotic Medications targeting small elements of behavior and then gradually adding other elements of Treatment of psychosis may require the behavior purchase female viagra 50 mg on-line, always working toward the use of antipsychotic medications (see Table ideal behavior. Antipsychotic medications, some- ing groups, individuals learn to make spe- times called neuroleptic medications or ciﬁc responses to speciﬁc social situations, major tranquilizers, do not cure psychosis as well as to recognize relevant social cues but rather control the symptoms. The ﬁrst and to determine appropriate action by antipsychotic drug, chlorpromazine (Thora- using the cues. Since involve speciﬁc interventions, such as role that time, numerous other antipsychotic modeling, feedback and reinforcement, medications have been developed. These and practice, in helping individuals to per- drugs are classiﬁed into different chemi- form speciﬁed behaviors reliably and to cal groups. Drugs in each group have vary- generalize the behavior to other situations. Specialized Groups Duration of treatment with antipsychot- Individuals with some types of mental ic medications is determined individual- illness may neglect their own needs of dai- ly and based on individuals’ life situation ly living, including personal hygiene, and condition. All individuals ing groups) may help individuals with should have their medications reviewed General Treatment of Psychiatric Disability 195 annually by a psychiatrist to evaluate the the tongue. Antiparkinsonian medications, such as benztropine (Cogentin) and trihexphenidyl Table 6–5 Common Antipsychotic Agents (Artane), are often prescribed along with antipsychotics to prevent extrapyramidal Trade Name Generic Name side effects. Tardive dyskinesia is best treat- ed through prevention, since the occur- Clozaril Clozapine rence of the symptom is frequently related Compazine Prochlorperazine to drug dosage. Individuals on antipsy- Haldol Haloperidol chotic medication must be carefully moni- Loxitane Loxapine tored by a physician so that the early Mellaril Thioridazine symptoms of tardive dyskinesia may be Navane Thiothixene identiﬁed and dosage of the medication Prolixin Fluphenazine adjusted to avoid permanent damage. Stelazine Trioridazine Individuals on antipsychotic medica- tions may also develop photosensitivity, It is believed that the symptoms of psy- which makes them more sensitive to the chosis may be due to excessive levels of effects of the sun and predisposes them to the neurotransmitter dopamine. Some medications that have quently, it has been postulated that anti- potent sedating effects may decrease alert- psychotic medications reduce symptoms ness and produce drowsiness. These symp- by blocking the action or transmission of toms usually subside within 2 weeks after dopamine. Because of this blocking, how- the individual begins to take the medica- ever, one of the side effects of antipsychot- tion; if they persist, alteration in medica- ic medications may be psychomotor symp- tion may be necessary. Individuals may toms similar to those seen in Parkinson’s also experience orthostatic hypotension, disease (see Chapter 3). These are called in which their blood pressure drops when extrapyramidal effects, because changes they move from a seated or prone position take place in the extrapyramidal tracts of to a standing position, resulting in dizzi- the central nervous system. Individuals may extrapyramidal effects of antipsychotic complain of other uncomfortable side ef- medications include dystonia, character- fects, such as dry mouth, after beginning anti- ized by severe contractions of the muscles psychotic medications. These symptoms of the jaw, neck, and eye so that the head generally subside within 2 weeks, howev- is turned to one side and the eyes look up- er. Men on antipsychotic medication may ward; akinesia, characterized by decreased become impotent or unable to ejaculate. Any that the individual cannot sit still or re- medication change should always be con- main in one place for any length of time. The most severe extrapyramidal side effect of antipsychotic medications is tardive Antidepressants dyskinesia, which consists of abnormal movements of the mouth, such as chew- Conditions in which depression is a ing motions or thrusting movements of symptom may be treated with antidepres- 196 CHAPTER 6 PSYCHIATRIC DISABILITIES sants. Although the exact way antidepres- ing MAO inhibitors ingest tyramine-con- sants work has not been determined, they taining foods, they may experience a are classiﬁed according to their presumed hypertensive crisis in which there is sudden mode of action. The most widely used and extreme elevation in blood pressure, antidepressants, tricyclic antidepressants, are which could result in stroke. The availabil- serotonin, thus increasing their concentra- ity of antidepressant medication that tion. Levels of both of these neurotransmit- could be used in a suicide attempt is a risk ters appear to be reduced in depression. The risk of attempted Monoamine oxidase (MAO) inhibitors, suicide may be higher when the antide- less frequently used antidepressants, are pressant begins to take effect because sui- thought to act by blocking the action of cidal impulses are still present and as the enzyme monoamine oxidase, which individuals’ energy returns so does their usually breaks down norepinephrine and motivation to attempt suicide. Although serotonin, so that the concentration of the antidepressants are an important aspect of neurotransmitters increases. In- Mood Stabilizers dividuals on tricyclic antidepressants may experience symptoms such as orthostatic Lithium is an antimanic agent used to hypotension (described previously), dry treat the manic symptoms in bipolar dis- mouth, or urinary retention. It is an element that occurs natural- possible side effect is the development of ly as a salt.
The term trophic means “food”; it is hormone testosterone (see chapter 20) order 50 mg female viagra amex. Endocrine System © The McGraw−Hill Anatomy order 100mg female viagra with visa, Sixth Edition Coordination Companies, 2001 Chapter 14 Endocrine System 463 6. Prolactin is secreted in both males and females, but it functions primarily in females after parturition. Pro- lactin assists other hormones in initiating and sustaining milk production by the mammary glands. The hypothala- mus plays an important role in the release of this hormone through the production of prolactin-inhibiting hormone (PIH), now known to be dopamine. When PIH is secreted, the secretion of prolactin is inhibited; when PIH is not se- creted, prolactin is released. The exact action of MSH in humans is unknown, but it can cause darkening of the skin by stimulating the dispersion of melanin granules within melanocytes. Secretion of MSH is stimulated by corticotropin-releasing hormone and inhibited by dopamine, both of which come from the hypothalamus. It then travels through axons in the in- fundibulum to the lobus nervosa, where it is stored and re- leased in response to neural impulses from the FIGURE 14. Oxytocin influences physiological activity cell bodies within the supraoptic and paraventricular nuclei of the hy- in the female reproductive system. These hormones are transported to the posterior pitu- end of gestation and causes uterine contractions during itary by nerve fibers of the hypothalamo-hypophyseal tract. It also stimulates contraction of the mammary gland alveoli and ducts, producing the milk-ejection reflex dur- ing lactation (see chapter 21). In males, a rise in oxytocin at the time of ejaculation has been measured, but the phys- iological significance of this hormone in males has yet to be demonstrated. The posterior pituitary is thus more of a if the pregnancy is prolonged or if the fetal membranes have ruptured and there is a danger of infection. In nursing mothers, for example, the stimulus of sucking acts via sensory 9. ADH is similar to oxy- nerve impulses to the hypothalamus to stimulate the reflex secre- tocin in its site of production and release. The major function of ADH is to inhibit ceptor neurons in the hypothalamus in response to a rise in the formation of urine in the kidneys, or more specifically, blood osmotic pressure; its secretion is inhibited by sensory im- to reduce the amount of water excreted from the kidneys. At one time, the anterior pituitary was called the “master Diabetes insipidus results from a marked decrease in ADH gland” because it secretes hormones that regulate some other en- output caused by trauma or disease to the hypothalamus or docrine glands (see table 14. The symptoms of this disease are polyuria (voiding cotrophic hormone (ACTH), thyroid-stimulating hormone excessive dilute urine), concentrated body fluids with dehydration, and a particularly heightened sensation of thirst. The anterior pituitary hormones also have posterior pituitary (pars nervosa of the neurohypophysis). These a trophic effect on their target glands in that the health of these two hormones, however, are actually produced in neuron cell glands depends on adequate stimulation by anterior pituitary bodies of the supraoptic nuclei and paraventricular nuclei of hormones. The anterior pituitary, however, is not really the mas- the hypothalamus. These nuclei within the hypothalamus are ter gland, because secretion of its hormones is in turn controlled thus endocrine glands; the hormones they produce are trans- by hormones secreted by the hypothalamus. Endocrine System © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 464 Unit 5 Integration and Coordination TABLE 14. Neurons in the hypothalamus secrete hormones into explain how the hypothalamus controls the secretion of the region of the median eminence, where they enter a net- each hormone. Which hormone secreted by the anterior pituitary does not through the pituitary stalk transports the hypothalamic hor- affect some other endocrine gland? Which hormone secreted by the pituitary gland affects scribed in chapter 16. Endocrine System © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 Chapter 14 Endocrine System 465 FIGURE 14. Endocrine System © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 466 Unit 5 Integration and Coordination FIGURE 14. Hypothalamic hormones (shown as dots) enter this system in the first set of capil- laries of the median eminence and are transported through the portal veins of the pituitary stalk to a second set of capillaries of the anterior pituitary. Description of the Thyroid Gland THYROID AND PARATHYROID GLANDS The thyroid gland is located in the neck, just below the larynx (fig.
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