By S. Dimitar. Midwestern State University. 2017.
Arginine va- Oxytocin secretion is also stimulated by neural input sopressin is made in humans generic avapro 300 mg otc. Although AVP and oxytocin from the female reproductive tract during childbirth avapro 300 mg generic. Cer- differ by only two amino acid residues, the structural dif- vical dilation before the beginning of labor stimulates ferences are sufficient to give these two molecules very dif- stretch receptors in the cervix. They are similar enough, how- through the CNS to oxytocin-secreting neurons. Oxytocin ever, for AVP to have slight oxytocic activity and for release stimulates the contraction of smooth muscle cells in oxytocin to have slight antidiuretic activity. They code for much larger mary glands and the female reproductive tract are discussed prohormones that contain the amino acid sequences for further in Chapter 39. AVP or oxytocin and for a 93-amino acid peptide called neurophysin (Fig. The neurophysin coded by the AVP gene has a slightly different structure than that coded by the oxytocin gene. Neurophysin is important in the pro- HORMONES OF THE ANTERIOR PITUITARY cessing and secretion of AVP, and mutations in the neuro- The anterior pituitary secretes six protein hormones, all of physin portion of the AVP gene are associated with central which are small, ranging in molecular size from 4. During the passage of the glands; they are called tropic (Greek meaning “to turn to”) or granules from the Golgi apparatus to axon terminals, pro- trophic (“to nourish”) hormones. For example, ACTH main- hormones are cleaved by proteolytic enzymes to produce tains the size of certain cells in the adrenal cortex and stim- AVP or oxytocin and their associated neurophysins. Similarly, TSH AVP or oxytocin secretion, action potentials are gener- maintains the size of the cells of the thyroid follicles and ated in these cells, triggering the release of AVP or oxy- stimulates these cells to produce and secrete the thyroid tocin and neurophysin from the axon terminals. The 4 3 substances diffuse into nearby capillaries and then enter two other tropic hormones, FSH and LH, are called go- the systemic circulation. FSH stimulates the development of follicles in the ovaries and regulates the process of spermatogenesis in the testes. AVP Increases the Reabsorption of LH causes ovulation and luteinization of the ovulated Water by the Kidneys graafian follicle in the ovary of the human female and stim- Two physiological signals, a rise in the osmolality of the ulates the production of the female sex hormones estrogen blood and a decrease in blood volume, generate the CNS and progesterone by the ovary. Chemical mediators of AVP re- the Leydig cells of the testis to produce and secrete the lease include catecholamines, angiotensin II, and atrial na- male sex hormone, testosterone.
Vita- of autoimmune diseases are systemic lupus min K is necessary for the formation of erythematosus and rheumatoid arthritis (see some clotting factors order 300mg avapro amex. For example cheap avapro 150 mg online, basophils (a type of body’s immune response and leave indi- white blood cell) are thought to have viduals more susceptible to disease. Be- some role in stopping the coagulation cause it is necessary to suppress the im- process once the bleeding is under control. Individuals with certain types of cancers, The term blood dyscrasias is used to such as lymphoma and leukemia (see describe a large group of disorders that Chapter 16), may become immunodeﬁcient affect the blood. Overuse or blood-forming organs may arise from a abuse of narcotics or steroid drugs can also number of different sources; may be man- alter the immune response. These disorders may be characterized by the overproduction of cells, The term hemostasis refers to a series the underproduction of cells, or defects in the of events that stop bleeding from dam- clotting mechanism. Platelets are involved in the important ﬁrst step in preventing exces- Anemia sive bleeding after an injury. Formed by special cells in the bone marrow, platelets Although not thought of as a disability are the smallest of the cells in the blood. Anemia may be a compli- blood cell disorders, or it may develop as cation associated with cancer or cancer a response to drugs or other foreign or tox- treatment (Bokemeyer & Foubert, 2004), ic agents. Anemia results when the rate of a symptom of dietary deﬁciency (Stabler destruction is greater than the ability of & Allen, 2004), a symptom of gastrointes- the body to produce red cells. The degree tinal disorders, or a side effect of treatment of anemia reﬂects the ability of the bone of gastrointestinal disorders (Andres, marrow to increase the production of red Loukili, Ben, & Noel, 2004; Bodemar, blood cells. Aplastic anemia Conditions that fall under the general can occur spontaneously, or it can result term anemia are characterized by a reduc- from damage to the bone marrow through tion in the amount of hemoglobin or the drugs, chemicals, or ionizing radiation. Anemias are Iron deﬁciency anemia, one of the most sometimes classiﬁed by the size and col- common types of anemia (Shah, 2004), is or of the red blood cell.
Many genetic abnormalities can be detected by aspirating a sample of this fluid and examining the cells ob- FIGURE 22 purchase avapro 300 mg free shipping. Genetic diseases purchase avapro 300mg fast delivery, such as Down syndrome, or trisomy 21 (in which there are three instead of two centa. Prior to delivery, the amnion is naturally or surgically rup- number–21 chromosomes), can be detected by examining chromo- tured, and the amniotic fluid (bag of waters) is released. Diseases such as Tay-Sachs disease, in which there is a de- As the fetus grows, the amount of amniotic fluid increases. For the near-term baby, almost 8 liters of fluid are completely replaced each day. Amniotic fluid is normally swallowed by the fetus and ab- sorbed in the GI tract. The fluid enters the fetal blood, and the Yolk Sac waste products it contains enter the maternal blood in the pla- The yolk sac is established during the end of the second week as cells from the trophoblast form a thin exocoelomic (ek'so-se˘- Down syndrome: from John L. Developmental © The McGraw−Hill Anatomy, Sixth Edition Development Anatomy, Postnatal Companies, 2001 Growth, and Inheritance 764 Unit 7 Reproduction and Development Decidua basalis Chorion frondosum Maternal vein Maternal Umbilical artery Chorion cord Amnion Amniotic sac containing amniotic fluid Placenta FIGURE 22. Blood from the embryo is carried to and from the chorion frondosum by the umbilical arteries and vein. The maternal tissue between the chorionic villi is known as the de- cidua basalis; this tissue, together with the villi, form the functioning placenta. Attached to It also contributes to the development of the urinary bladder. After birth, the urachus becomes a fibrous cord called form in the wall of the yolk sac. During the fourth week, they the median umbilical ligament that attaches to the urinary bladder.
They are cule contain receptors that are sensitive to gravity and linear completely separated 150mg avapro, except at the narrow apex of the cochlea buy 300 mg avapro amex, movement (acceleration) of the head. Between the scala vestibuli and the scala tympani is Semicircular Canals the cochlear duct, the triangular middle chamber of the cochlea. The roof of the cochlear duct is called the vestibular membrane, Posterior to the vestibule are the three bony semicircular canals, and the floor is called the basilar membrane. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 Chapter 15 Sensory Organs 521 FIGURE 15. Within the cochlear duct is a specialized structure called the spiral organ (organ of Corti). The sound receptors that transform mechanical vibrations into nerve impulses are located along the basilar membrane of this structure, making it the func- Hair tional unit of hearing. The epithelium of the spiral organ consists cells of supporting cells and hair cells (figs. The bases of the hair cells are anchored in the basilar membrane, and their tips are embedded in the tectorial membrane, which forms a gelatinous canopy over them. Kardon, Tissues and Organs: A Text-Atlas of Scanning Electron Microscopy. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 522 Unit 5 Integration and Coordination FIGURE 15. The scala vestibuli and the scala tympani, which contain perilymph, are continuous at the helicotrema. The cochlear duct, which con- tains endolymph, separates the scala vestibuli and the scala tympani. Sounds of low frequency (blue arrow) cause pressure waves of perilymph to pass through the helicotrema and displace the basilar membrane near its apex. Sounds of medium frequency (green arrow) cause pressure waves to displace the basilar membrane near its center.