By V. Agenak. Lutheran Bible Institute.

List the categories of corticosteroids and identify the zones of the adrenal cortex that secrete these hormones discount reglan 10mg with mastercard. Excessive stimulation of the adrenal medulla can result in de- pletion of the body’s energy reserves generic 10 mg reglan with amex, and high levels of corti- costeroid secretion from the adrenal cortex can significantly impair Van De Graaff: Human V generic reglan 10 mg mastercard. Endocrine System © The McGraw−Hill Anatomy generic 10mg reglan with visa, Sixth Edition Coordination Companies purchase 10mg reglan fast delivery, 2001 474 Unit 5 Integration and Coordination FIGURE 14. These changes are elicited by neural impulses from the hypothalamus that directly influence body tissues and by impulses to the adrenal medulla that secondarily influence the same body tis- sues through the release of epinephrine. The gonads are mixed glands in that they produce GONADS AND OTHER both sex hormones and sex cells, or gametes (see chapters 20 ENDOCRINE GLANDS and 21). The gonads produce sex hormones that control the development and function of the male and female reproductive systems. Addi- Testes tionally, many other organs secrete hormones that help regulate The interstitial cells of the testes produce and secrete the male digestion, metabolism, growth, and immunity. Testosterone controls the development Objective 16 Discuss the endocrine functions of the gonads. It also promotes the male secondary sex Objective 17 Describe the structure and location of the characteristics (see chapter 20) and somewhat determines the pineal and thymus glands and their endocrine functions. The The endocrine function of the ovaries is the production of the male gonads are called testes and the female gonads are called female sex hormones, estrogens and progesterone. Endocrine System © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 Chapter 14 Endocrine System 475 Melatonin H H H O CH3O C C N C CH3 N H H H Pineal gland Day Inhibition Sympathetic neurons Night Retinohypothalamic Stimulation tract Superior cervical Suprachiasmatic nucleus ganglion (the “biological clock”) FIGURE 14. The secretion of melatonin by the pineal gland is stimulated by sympathetic axons originating in the superior cervical ganglion. Activity of these neurons is regulated by the cyclic activity of the suprachiasmatic nucleus of the hypothalamus, which sets a circadian rhythm. They are also produced in the placenta, adrenal cortex, and even in the testes of the male. It Progesterone is produced by the corpus luteum and is pri- begins to regress in size at about the age of 7, and in the adult it marily associated with pregnancy in preparing the uterus for im- appears as a thickened strand of fibrous tissue. Although it lacks direct nervous connection to the rest of Most cultures of the world practice birth control, or contra- the brain, the pineal gland is highly innervated by the sympa- ception, in one form or another. It has a long history, dating back to the ancient Egyptians who used various substances to inhibit thetic division of the ANS from the superior cervical ganglion. In the age of hormonal biochemistry, The function of the pineal gland in some vertebrates is birth-control techniques have become increasingly sophisticated. Secretion of The female, rather than the male, has been the target of hormonal its principal hormone, melatonin, follows a circadian (daily) birth-control techniques for the following reasons: (1) ovulation is cyclic; (2) the genetic structure of each ovum is established by the rhythm tied to daily and seasonal changes in light. Melatonin is time of the female’s birth, whereas sperm production is a continuous thought to affect the hypothalamus by stimulating the secretion process, and therefore more vulnerable to genetic damage; (3) the of certain releasing factors (fig 14. These factors in turn female system has more potential sites for hormonal interference than does the male system; and (4) the female is usually more con- scientious about practicing birth control because she has far more invested in pregnancy than does the male. Endocrine System © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 476 Unit 5 Integration and Coordination affect the secretion of gonadotrophin and the ACTH from the adenohypophysis of the pituitary gland. Excessive melatonin se- Thyroid cartilage cretion in humans is associated with a delay in the onset of pu- of larynx berty; however the role of melatonin in sexual maturation is still highly controversial. Although the size of the thymus varies Thymus considerably from person to person, it is relatively large in new- borns and children and then sharply regresses in size after pu- berty. Besides decreasing in size, the thymus of adults becomes Left lung infiltrated with strands of fibrous and fatty connective tissue. The principal function of the thymus is associated with the lymphatic system (see chapter 16) in maintaining body immu- nity through the maturation and discharge of a specialized group of lymphocytes called T cells (thymus-dependent cells). The thy- mus also secretes a hormone called thymosin, which is believed to stimulate the T cells after they leave the thymus. Endocrine System © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 Developmental Exposition velopment of the testes and ovaries is discussed in chapters 20 The Endocrine System and 21, respectively. Pituitary Gland EXPLANATION Although the pituitary gland is a single organ, it is actually com- The endocrine system is the only anatomical body system whose posed of two distinct types of tissues that have different embry- organs are not structurally connected. These two types of tissues release different hormones isolated from each other and are distributed throughout the body, and are under different control systems. The anterior portion of each endocrine organ has a separate and independent develop- the hypophysis, called the adenohypophysis, develops from ecto- ment.

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The fact that there is a cholinergic projection from the pedunculo pontine tegmental nucleus to the dopomine neurons of the ventral tegmental area (VTA) and that its excitatory effect is mediated through nicotinic receptors could also implicate them and so ACh 10mg reglan amex, in the reward process discount reglan 10 mg line. This is thought to be mediated in part through the mesolimbic and mesocortical dopamine pathways arising from the VTA and may offer an explanation for the addictive nature of nicotine and smoking order reglan 10 mg with mastercard. REFERENCES AND FURTHER READING Brown reglan 10mg generic, DA (1983) Slow cholinergic excitation Ð a mechanism for increasing neuronal excitability reglan 10 mg. Brown, DA, Gahwiler, BH, Marsh, SJ and Selyanko, AA (1986) Mechanisms of muscarinic excitatory synaptic transmission in ganglia and brain. Caulfield, MP and Birdsall, NMJ (1998) Classification of muscarinic acetylcholine receptors. Changeux, JP (1990) The nicotinic acetylcholine receptor: an allosteric protein prototype of ligand-gated ion channels. Changeux, JP, Bertrand, D, Corringer, PJ, Dehoene, S, Edelstein, S, Leno, C, Novere, N le, Marubio, L, Picciotto, M and Zoli, M (1998) Brain nicotinic receptors: structure and regulation, role in learning and reinforcement. Cole, AE and Nicoll, RA (1984) Characterization of a slow cholinergic post synaptic potential recorded in vitro from rat hippocampal pyramidal cells. Collier, B and Mitchell, JF (1967) Release of ACh duringconsciousness and after brain lesions. Cordero-Erausquin, M, Marubio, LM, Klink, R and Changeux JP (2000) Nicotinic receptor function: new perspectives from knockout mice. Eglen, RM and Watson, N (1996) Selective muscarinic receptor agonists and antagonists. Flentge, F, Venema, K, Koch, T and Korf, J (1997) An enzyme-reactor for electrochemical monitoringof choline and acetylcholine. Applications in high-performance liquid chromato- graphy, brain tissue, microdialysis and cerebral fluid. Greenfield, SA (1991) A noncholinergic action of acetylcholinesterase (AchE) in the brain. Hersch, SM, Guten Kunst, CA, Rees, HD, Heilman, CT and Levey, AJ (1994) Distribution of M1±M4 muscarinic receptor proteins in the rat striatum. Light and electron microscopic immunochemistry usingsubtype-specific antibodies. Hulme, EC, Birdsall, NJM and Buckley, NJ (1990) Muscarinic receptor subtypes. Jones, S, Sudweeks, S and Yakel, JL (1999) Nicotinic receptors in the brain: correlating physiology with function. Levey, A, Kitt, CA, Simmonds, WF, Price, DL and Brann, MR (1991) Identification and localisation of muscarinic acetylcholine receptor proteins in brain with subtype specific antibodies. Lindstrom, JM (1997) Nicotinic acetylcholine receptors in health and disease. McCormick, DA and Prince, DA (1986a) Mechanism of action of acetylcholine in the guinea-pig cerebral cortex in vitro. Wall, SJ, Yasada, RP, Hory, F, Flagg, S, Martin, BM, Ginns, EI and Wolfe, BB (1991) Production of antisera selective for M1 muscarinic receptors usingfusion proteins: distribution of M1 receptors in rat brain. Webster, HH and Jones, BE (1988) Neurotoxic lesions of the dorsalateral pontomesencephalic tegmentum-cholinergic cell area in the rat. Whittaker, VP (1987) Cholinergic synaptic vesicles from the electromotor nerve terminals of Torpedo: composition and life cycle. Woolf, NJ (1991) Cholinergic systems in mammalian brain and spinal cord. Zinnerman, H, Volknandt, W, Wittich, B and Hausinger, A (1993) Synaptic vesicle lifecycle and synaptic turnover. Edited by Roy Webster Copyright & 2001 John Wiley & Sons Ltd ISBN: Hardback 0-471-97819-1 Paperback 0-471-98586-4 Electronic 0-470-84657-7 7 opam ine (D ) R. WEBSTER Dopamine (3:4 dihydroxyphenylethylamine), like noradrenaline and adrenaline, is a catecholamine and in addition to its independent neurotransmitter role in the CNS it is a precursor to noradrenaline (NA) in all central and peripheral noradrenegic neurons. PATHWAYS It became possible to visualise neurons which contained catecholamines when it was discovered that these amines reacted with formaldehyde vapour (later replaced by glyoxylic acid) to produce isoquinoline condensation products which emitted a bright- green fluorescence when visualised under ultra-violet light. This was distinguishable from the yellow fluorescence of 5-HT and could be separated from that for NA by appropriate pharmacological manipulations or adjustments to the microscopic techniques. Using this procedure, which is known as the Falk±Hillarp technique, Dahlstrom and Fuxe (1964) located and numbered nuclei in the hindbrain (pons medulla) in which either DA (A8±A12) or NA (1±7) was concentrated. Most of the DA cell bodies (about 400 000) in the human brain are found in the A9 nucleus which forms the zona compacta (dorsal part) of the substantia nigra (SN), although a few cell bodies are found in the more ventral zona reticulata and in the zona lateralis as well (Fig. A8 is lateral, caudal and somewhat dorsal to A9 and A10 whereas A10 is ventral to A9.

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Peripheral Nervous © The McGraw−Hill Anatomy discount reglan 10mg with mastercard, Sixth Edition Coordination System Companies buy discount reglan 10mg on-line, 2001 416 Unit 5 Integration and Coordination TABLE 12 10 mg reglan with amex. Motor impulses through fibers from the anterior branches of spinal nerves C5 through the paired phrenic nerves cause the diaphragm to contract discount reglan 10 mg otc, mov- T1 and a few fibers from C4 and T2 reglan 10 mg without a prescription. The roots converge to form trunks, and The nerves of the cervical plexus are summarized in the trunks branch into divisions. Brachial Plexus The brachial plexus may suffer trauma, especially if the clavi- cle, upper ribs, or lower cervical vertebrae are seriously frac- The brachial plexus is positioned to the side of the last four cer- tured. Occasionally, the brachial plexus of a newborn is severely vical vertebrae and the first thoracic vertebra. It is formed by the strained during a difficult delivery when the baby is pulled through anterior rami of C5 through T1, with occasional contributions the birth canal. In such cases, the arm of the injured side is para- lyzed and eventually withers as the muscles atrophy in relation to the from C4 and T2. Each brachial plexus innervates called a brachial block or brachial anesthesia. The site for injection of the entire upper extremity of one side, as well as a number of the anesthetic is located midway between the base of the neck and the shoulder, posterior to the clavicle. Structurally, the brachial plexus is divided into roots, trunks, divisions, and cords (figs. The roots of Five major nerves—the axillary, radial, musculocutaneous, the brachial plexus are simply continuations of the anterior rami ulnar, and median—arise from the three cords of the brachial of the cervical nerves. The anterior rami of C5 and C6 converge plexus to supply cutaneous and muscular innervation to the to become the superior trunk, the C7 ramus becomes the mid- upper extremity (table 12. The axillary nerve arises from the dle trunk, and the ventral rami of C8 and T1 converge to be- posterior cord. It provides sensory innervation to the skin of the come the inferior trunk. Each of the three trunks immediately shoulder and shoulder joint, and motor innervation to the del- divides into an anterior division and a posterior division. The posterior cord from the posterior cord and extends along the posterior aspect of is formed by the convergence of the posterior divisions of the the brachial region to the radial side of the forearm. It provides upper, middle, and lower trunks; hence, it contains fibers from sensory innervation to the skin of the posterior lateral surface of C5 through C8. The medial cord is a continuation of the ante- the upper extremity, including the posterior surface of the hand rior division of the lower trunk and primarily contains fibers from (fig. The lateral cord is formed by the convergence of the of the elbow joint, the brachioradialis muscle that flexes the anterior division of the upper and middle trunk and consists of elbow joint, and the supinator muscle that supinates the forearm fibers from C5 through C7. Peripheral Nervous © The McGraw−Hill Anatomy, Sixth Edition Coordination System Companies, 2001 Chapter 12 Peripheral Nervous System 417 FIGURE 12. Cervical plexus region Deltoid muscle Brachial plexus region Musculocutaneous nerve Brachiocephalic artery Median nerve Subclavian artery Ulnar nerve Medial pectoral nerve Medial antebrachial cutaneous nerve Pectoralis major muscle Thoracodorsal nerve Serratus anterior muscle Latissimus dorsi muscle FIGURE 12. Peripheral Nervous © The McGraw−Hill Anatomy, Sixth Edition Coordination System Companies, 2001 TABLE 12. Peripheral Nervous © The McGraw−Hill Anatomy, Sixth Edition Coordination System Companies, 2001 Chapter 12 Peripheral Nervous System 419 Posterior cord of Posterior cord of Lateral cord of brachial plexus brachial plexus brachial plexus Medial cord of Lateral cord of brachial plexus brachial plexus Medial cord of brachial plexus Musculocutaneous nerve Biceps brachii m. Crutch The motor innervation of the ulnar nerve is to two muscles of paralysis may result when a person improperly supports the the forearm and the intrinsic muscles of the hand (except some weight of the body for an extended period of time with a crutch pushed tightly into the axilla. Likewise, dislocation of the shoulder frequently traumatizes the The ulnar nerve can be palpated in the ulnar sulcus between radial nerve. Children are particularly at risk as adults yank on their the medial epicondyle of the humerus and the olecranon of arms. A fracture to the body of the humerus may damage the radial the ulna (see fig. This area is commonly known as the “funny nerve, which parallels the bone at this point. As a result, the joints of the fingers, perception of this trauma is a painful tingling that extends down the wrist, and elbow are in a constant state of flexion. It provides sensory innervation to the skin of the posterior lat- The median nerve arises from the medial cord. It provides eral surface of the arm and motor innervation to the anterior sensory innervation to the skin on the radial portion of the palm muscles of the brachium (fig. Peripheral Nervous © The McGraw−Hill Anatomy, Sixth Edition Coordination System Companies, 2001 420 Unit 5 Integration and Coordination Posterior cord of brachial plexus Lateral cord of brachial plexus Medial cord of brachial plexus Medial nerve Pronator teres m. Peripheral Nervous © The McGraw−Hill Anatomy, Sixth Edition Coordination System Companies, 2001 Chapter 12 Peripheral Nervous System 421 L1 Iliohypogastric nerve L2 Ilioinguinal nerve Genitofemoral nerve L3 Lateral femoral L4 cutaneous nerve Femoral nerve L5 Roots Saphenous Anterior divisions nerve Obturator Posterior divisions nerve Lumbosacral trunk FIGURE 12.

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