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The sella turcica that supports the (a) TSH (c) triiodothyronine alpha and beta cells discount amitriptyline 75 mg on-line depression symptoms heart palpitations, oxyphil cells buy amitriptyline 50 mg low price depression years, follicular pituitary gland is located in which bone? Explain the causes of each of the (b) the frontal bone Essay Questions following endocrine diseases: gigantism, (c) the sphenoid bone acromegaly, pituitary cachexia, and 1. Explain how the nervous and endocrine (d) the occipital bone pituitary dwarfism. List the glands of the endocrine system promoting the maturation of the brain is and describe their general locations. Why is this a what sense might this description be (a) It develops from mesoderm. A 38-year-old woman experienced a (c) Its secretion prepares the body for the 5. Which endocrine glands, or portions of milky discharge through the nipples of her fight-or-flight response. Which develop as an outgrowth or and her youngest child was 7 years old. Why is the pituitary frequently considered galactorrhea—the medical term for a the hormone insulin is true? List the hormones secreted by the both breasts—and scheduled her for a pancreatic islets. Describe the location and gross structure benign growth on the pituitary gland. What hormones How could a tumor of the pituitary result glycogen and fat. List the hormones secreted by the thyroid muster enough energy to go out on a date. Match the hormone with the primary agent gland and discuss the general function of She’s been putting on weight, she’s always that stimulates its secretion. Endocrine System © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 486 Unit 5 Integration and Coordination complains of weakness. When she finally competitive spirit needed to step in as the Explain why giving growth hormones goes to her doctor, he finds her to have a new star center—if only he weren’t to an adult does not change the person’s slow pulse and low blood pressure. Explain the physical changes that tests indicate thyroid hormone on, you start slipping growth hormone can occur when an adult is administered deficiency—a condition termed into Bubba’s morning orange juice—a growth hormones. Suppose a person with a normal thyroid very common and occurs 8 times more After a time, however, you begin to gland took thyroid pills. What Brenda’s symptoms be typical of this In fact, he hasn’t grown an inch. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 Sensory Organs 15 Overview of Sensory Perception 488 Classification of the Senses 488 Somatic Senses 490 Olfactory Sense 495 Gustatory Sense 496 Visual Sense 499 Developmental Exposition: The Eye 515 Senses of Hearing and Balance 516 CLINICAL CONSIDERATIONS 527 Developmental Exposition: The Ear 528 Clinical Case Study Answer 533 Chapter Summary 534 Review Activities 535 Clinical Case Study A 50-year-old man complained to his family doctor of progressive hearing loss in his right ear. In order to rule out visible abnormalities or wax buildup, the physician performed an otoscopic examination, which revealed no abnormalities. The physician then struck a tuning fork and placed it on the skin over the mastoid process of the patient’s right temporal bone. The patient immediately exclaimed, “I can hear that really well, even in my bad ear! The doctor then moved the instrument 2 centimeters away from the same ear. The doctor explained that although someone with normal hearing will hear a vibrating fork when it is held against the mastoid process, the person will hear it better when it is held just outside the external acoustic canal. What components of the patient’s hearing mechanism were bypassed when the handle of the tuning fork was placed on his mastoid process? FIGURE: Hearing loss may be congenital (occurring prenatally) or acquired (occurring Hints: The hearing organs of the inner ear can receive and effectively process sound waves di- postnatally), and there are a number of factors rectly from the bone in which they are encased. Scenescent (age-related) waves being processed through the mastoid process. Carefully read the section on the structure hearing loss afflicts all elderly people to one of the ear and the one on sound waves and neural pathways for hearing. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 488 Unit 5 Integration and Coordination in the visible spectrum.

A semenalysis reveals the relative number of sperm (sperm count) generic 25 mg amitriptyline fast delivery anxiety zone als, sperm vitality discount 25 mg amitriptyline fast delivery depression kidney disease, and chemical nature of the fluid medium in a sample ejaculate. Male Reproductive © The McGraw−Hill Anatomy, Sixth Edition Development System Companies, 2001 698 Unit 7 Reproduction and Development (the blastocyst), pregnancy, and delivery of a baby. The more INTRODUCTION TO THE MALE complex reproductive system of the female also provides a means REPRODUCTIVE SYSTEM for nourishing the baby through the secretion of milk from the mammary glands. In addition, like in the male, another function The organs of the male and female reproductive systems are is to produce and secrete sex hormones, which maintain the fe- adapted to produce and allow the union of gametes that contain male sex organs and contribute to the female libido. A random combination of the genes during sexual In this chapter we will consider the anatomy of the male reproduction results in the propagation of individuals with genetic reproductive system; the female reproductive system is the focus differences. Objective 1 Explain why sexual reproduction is biologically advantageous. Objective 2 List the functions of the male reproductive Categories of Reproductive Structures system and compare them with those of the female. The structures of the male reproductive system can be catego- Objective 3 Distinguish between primary and secondary rized on a functional basis as follows: sex organs. The primary sex organs are called go- nads; specifically, the testes in the male. Gonads produce Unlike other body systems, the reproductive system is not essen- the gametes, or spermatozoa, and produce and secrete sex tial for the survival of the individual; it is, however, required for hormones. The secretion of male sex hormones, called an- the survival of the species. It is through reproduction that addi- drogens, at the appropriate times and in sufficient quanti- tional individuals of a species population are produced and the ties causes the development of secondary sex organs and genetic code passed from one generation to the next. Secondary sex organs are those ual reproduction, in which genes from two individuals are com- structures that are essential in caring for and transporting bined in random ways with each new generation, offers the spermatozoa. The three categories of secondary sex organs overwhelming advantage of introducing great variability into a are the sperm-transporting ducts, the accessory glands, and population. This variability of genetic constitution helps ensure the copulatory organ. The ducts that transport sperm in- that some members of a population will survive changes in the clude the epididymides, ductus deferentia, ejaculatory ducts, environment over evolutionary time. The male accessory reproductive glands are The reproductive system is unique in two other respects. The penis, which contains erectile tissue, is the cop- “turned on” at puberty by the actions of sex hormones sets the re- ulatory organ. Secondary sex characteris- other organ systems of the body exhibit slight sexual differences, tics are features that are not essential for the reproductive no other system approaches the level of dissimilarity of the repro- process but are generally considered sexual attractants. The male and female reproductive systems complement The organs of the male reproductive system are shown in each other in their common purpose of producing offspring. The female not only produces her own gametes cate whether they are primary or secondary sex organs. With respect to the other body systems, discuss the latent male, but her reproductive organs are specialized to provide sites (delayed) development of the reproductive system. Male Reproductive © The McGraw−Hill Anatomy, Sixth Edition Development System Companies, 2001 Chapter 20 Male Reproductive System 699 Ureter Ampulla of ductus deferens Ampulla of ductus deferens Ejaculatory duct of ductus deferens Testis (sectioned to show testicular lobules) FIGURE 20. Male Reproductive © The McGraw−Hill Anatomy, Sixth Edition Development System Companies, 2001 700 Unit 7 Reproduction and Development their position relative to the pelvic region of the body. Organ(s) Function(s) The external appearance of the scrotum varies at different times in the same individual as a result of the contraction and re- Testes laxation of the scrotal muscles. Both the dartos and the cremaster involuntarily contract Ductus deferentia Store spermatozoa; convey spermatozoa to the in response to low temperatures to move the testes closer to the ejaculatory ducts heat of the body in the pelvic region. The cremaster muscle is a Ejaculatory ducts Receive spermatozoa and additives to produce continuation of the internal abdominal oblique muscle of the ab- seminal fluid dominal wall, which is derived as the testes descend into the Seminal vesicles Secrete alkaline fluid containing nutrients and prostaglandins; helps neutralize the acidic scrotum. Because it is a skeletal muscle, it can be contracted vol- environment of the vagina untarily as well. When the scrotal muscles are contracted, the Prostate Secretes acidic fluid that enhances motility of scrotum appears tightly wrinkled as the testes are pulled closer to spermatozoa the warmth of the body wall. High temperatures cause the dartos Bulbourethral glands Secrete fluid that lubricates the urethra and end and cremaster muscles to relax and the testes to be suspended of the penis lower in the relaxed scrotum.

What is clear is that it involves a complex cascade of regulatory processes focusing on proteins bound to vesicle membranes buy 75 mg amitriptyline overnight delivery depression symptoms behaviour, the axolemma and some cytoplasmic factors (see Calakos 96 NEUROTRANSMITTERS order amitriptyline 75mg depression test hindi, DRUGS AND BRAIN FUNCTION Figure 4. An increase in intracellular Ca2‡ triggers phosphorylation of synapsin I which dissociates from the vesicular membrane. This frees the vesicles from the fibrin microfilaments and makes them available for transmitter release at the active zone of the nerve terminal and Scheller 1996). The following sections will deal with those factors about which most is known and which are thought to have a prominent role in exocytosis. The extent to which this scheme explains release from large dense-cored vesicles is unclear, not least because these vesicles are not found near the active zone. DOCKING AND FUSION Because exocytosis is so rapid, it is believed that Ca2‡ must trigger release from vesicles which are already docked at the active zone. The processes leading to docking and fusion of the vesicle with the axolemma membrane are thought to involve the formation of a complex between soluble proteins (in the neuronal cytoplasm)and those bound to vesicular or axolemma membranes. Much of this evidence is based on studies of a wide range of secretory systems (including those in yeast cells)but which are thought to be conserved in mammalian neurons. From evidence collected to date, a scheme has emerged, known as the SNARE hypothesis (see Sollner and Rothman 1994)(Fig. Evidence, largely derived from studies of the Golgi apparatus, suggests that SNAPs have a general role in protein± protein interactions underlying membrane fusion. It is envisaged that this complex of the two SNARES enables sequential binding of the soluble SNAPs and NSF. Subsequent hydrolysis of ATP by NSF enables dissociation of the complex and fusion of the membrane so that the vesicle contents can be discharged into the synapse. It is thought that synaptic vesicle docking to the presynaptic plasma membrane requires the removal of a regulatory cytosolic protein, n-sec-1, from a VAMP (synaptobrevin)binding site on syntaxin. This results in the dissociation of synaptotagmin from the SNARE complex and binding of SNAPs and NSF, thus initiating fusion. How the interconversion of these complexes occurs and which components trigger these processes is poorly understood. Proteins such as rab 3A, Ca2‡ binding proteins and Ca2‡ channels are likely to be involved. For instance, injection of recombinant SNAP into the squid giant axon increases vesicular exocytosis. Also, membrane SNAP-25 and syntaxin are both targets for botulinum toxin while the vesicule protein, synaptobrevin, is a target for tetanus and botulinum toxins; both these toxins are well known for disrupting transmitter release. How all these processes are influenced by Ca2‡ is uncertain but another vesicle membrane-bound protein, synaptotagmin, is widely believed to effect this regulatory role (Littleton and Bellen 1995). Synaptotagmin has a single membrane-spanning domain with the NH2±tail penetrating the vesicle and the COOH±tail extending into the cytoplasm. This tail binds Ca2‡ and could enable synaptotagmin to act as a Ca2‡-sensor but, although it is found in adrenergic and sensory neurons, it appears to be absent from motor neurons. Another protein, synaptophysin (p38), is the most abundant of the vesicle proteins and is found in the membranes of both SSVs and LDCVs. Its transmembrane structure resembles that of connexins which form gap junctions and has provoked the theory that neuronal excitation might cause synaptophysin to act as a fusion pore. There is no doubt that many other factors are involved in regulating the docking±fusion±extrusion process, including the Rab family of GTP-binding proteins and the Rab3 effectors, Rabphilin and Rim. For a detailed review of the role of all these factors in the exo- cytotic cycle, see Benfanati, Onofri and Giovedi 1999. Early experiments using stimulated sympathetic nerve/end-organ preparations in situ, or synaptosomes, indicated that release of [3H]noradrenaline was attenuated by exposure to unlabelled, exogenous transmitter. This action was attributed to presynaptic adrenoceptors, designated a2-adrenoceptors, which were functionally distinct from either a1-orb-adrenoceptors. Later experiments have confirmed that a2-adrenoceptors comprise a family of pharmacologically and structurally distinct adrenoceptor subtypes. For instance, autoreceptors can only be synthesised in the cell bodies of neurons and are delivered to the terminals by axoplasmic transport.

With blocked experimentally with tetrodotoxin amitriptyline 25mg with mastercard depression symptoms feeling empty, every cycle of maximum inhibition generic 75mg amitriptyline with visa depression definition merriam webster, no contractions can occur in response the electrical slow wave triggers an intense discharge of ac- to a slow wave (see Fig. Contractions between the two ex- inhibitory neural activity after the application of tremes are graded in strength according to the number of A Neural 1 sec discharge Tetrodotoxin 10 sec B Muscle contraction Ongoing Neural discharge discharge blocked by tetrodotoxin FIGURE 26. Ongoing firing with tetrodotoxin, every cycle of the electrical slow wave trig- of a subpopulation of inhibitory motor neu- gers discharge of action potentials and large-amplitude con- rons to the intestinal circular muscle prevents electrical slow tractions. B, waves from triggering the action potentials that trigger con- Record of muscle contractile activity before and after applica- tractions. CHAPTER 26 Neurogastroenterology and Gastrointestinal Motility 463 CLINICAL FOCUS BOX 26. It is characterized by defecation difficulty untary control over the muscular mechanisms of conti- or failure. This condition is tested clinically by distending an colon, because the proximal colon may become grossly intrarectal balloon. The healthy subject will perceive the enlarged with impacted feces, or congenital agan- distension with an instilled volume of 15 mL or less, glionosis, because the ganglia of the ENS fail to develop whereas the sensory-deprived patient either will not report in the terminal region of the large intestine. Mutations in any sensation at all or will require much larger volumes RET or endothelin genes account for the disease in some before becoming aware of the distension. Incompetence of the internal anal sphincter is usually Enteric neurons may be absent in the rectosigmoid re- related to a surgical or mechanical factor or perianal dis- gion only, in the descending colon, or in the entire colon. Disorders of the The aganglionic region appears constricted as a result of neuromuscular mechanisms of the external sphincter and continuous contractile activity of the circular muscle, pelvic floor muscles may also result from surgical or me- whereas the normally innervated intestine proximal to the chanical trauma, such as during childbirth. Physiological deficiencies of the skeletal motor mech- The constricted terminal segment of the large intestine anisms can be a significant factor in the common occur- in Hirschsprung’s disease presents a functional obstruc- rence of incontinence in older adults. Constriction ing tone of the internal anal sphincter does not seem to and narrowing of the lumen of the segment reflects un- decrease with age, the strength of contraction of the ex- controlled myogenic contractile activity in the absence of ternal anal sphincter does weaken. Moreover, the stri- inhibitory motor neurons ated muscles of the external anal sphincter and pelvic Incontinence is an inappropriate leakage of feces and floor lose contractile strength with age. This condition flatus to a degree that it disables the patient by disrupting occurs in parallel with a deterioration of nervous func- routine daily activities. As discussed earlier, the mecha- tion, reflected by decreased conduction velocity in fibers nisms for maintaining continence involve the coordinated of the pelvic nerves. Clinical examination with intra-anal interactions of several different components. Conse- manometry reveals a decreased ability of the patient quently, sensory malfunction, incompetence of the inter- with disordered voluntary muscle function to increase in- nal anal sphincter, or disorders of neuromuscular mecha- tra-anal pressure when asked to “squeeze” the intra-anal nisms of the external sphincter and pelvic floor muscles catheter. This oc- Control by Inhibitory Motor Neurons of the Length of In- curs coincidently with control of contractile strength. Con- testine Occupied by a Contraction and the Direction of tractions can only occur in segments where ongoing inhi- Propagation of Contractions. The state of activity of in- bition has been inactivated, while it is prevented in hibitory motor neurons determines the length of a con- adjacent segments where the inhibitory innervation is ac- CLINICAL FOCUS BOX 26. As a re- Failure of peristalsis in the esophageal body or failure of the sult, the ingested material does not enter the stomach and lower esophageal sphincter to relax will result in dysphagia accumulates in the body of the esophagus. Some people show abnormally megaesophagus, in which distension and gross enlarge- high pressure waves as peristalsis propagates past the ment of the esophagus are evident. This condition, cases of achalasia, peristalsis does not occur in response called nutcracker esophagus, is sometimes associated to a swallow. Achalasia is a disorder of inhibitory motor neurons in In diffuse spasm, organized propagation of the peri- the lower esophageal sphincter. The number of neurons staltic behavioral complex fails to occur after a swallow. In- in the lower esophageal sphincter is reduced, and the lev- stead, the act of swallowing results in simultaneous con- els of the inhibitory neurotransmitter VIP and the enzyme tractions all along the smooth muscle esophagus. This degenerative disease manometric tracings, this response is observed as a syn- results in a loss of the inhibitory mechanisms for relaxing chronous rise in intraluminal pressure at each of the the sphincter with appropriate timing for a successful recording sensors. Myogenic contraction occurs in segments of intestine where inhibitory motor neurons are inactive.