By M. Tempeck. Texas A&M University, Corpus Christi. 2018.
Blood volume and arterial the fight-or-flight response discount nootropil 800 mg visa, diving buy nootropil 800mg amex, thermoregulation, pressure are monitored by stretch receptors in the heart and standing, and exercise. Sympathetic fibers to the heart release NE, which binds Neural regulation of the cardiovascular system involves the to 1-adrenergic receptors in the sinoatrial node, the atri- firing of postganglionic parasympathetic and sympathetic oventricular node and specialized conducting tissues, and neurons, triggered by preganglionic neurons in the brain cardiac muscle. Stimulation of these fibers causes increased (parasympathetic) and spinal cord (sympathetic and heart rate, conduction velocity, and contractility. Afferent input influencing these neurons The two divisions of the autonomic nervous system tend comes from the cardiovascular system, as well as from other to oppose each other in their effects on the heart, and ac- organs and the external environment. Briefly, the heart is innervated by Blood vessels (except those of the external genitalia) re- parasympathetic (vagus) and sympathetic (cardioaccelera- ceive sympathetic innervation only (see Fig. Parasympathetic fibers release neurotransmitter is NE, which binds to 1-adrenergic re- acetylcholine (ACh), which binds to muscarinic receptors ceptors and causes vascular smooth muscle contraction and of the sinoatrial node, the atrioventricular node, and spe- vasoconstriction. Stimulation of parasympathetic the adrenal medulla, binds to 2-adrenergic receptors of fibers causes a slowing of the heart rate and conduction ve- vascular smooth muscle cells, especially coronary and locity. The ventricles are only sparsely innervated by skeletal muscle arterioles, producing vascular smooth mus- parasympathetic nerve fibers, and stimulation of these cle relaxation and vasodilation. Postganglionic parasympa- fibers has little direct effect on cardiac contractility. Some thetic fibers release ACh and nitric oxide (NO) to blood cardiac parasympathetic fibers end on sympathetic nerves vessels in the external genitalia. ACh causes the further re- and inhibit the release of norepinephrine (NE) from sym- lease of NO from endothelial cells; NO results in vascular pathetic nerve fibers. Therefore, in the presence of sympa- smooth muscle relaxation and vasodilation. Parasympathetic Sympathetic Vagus nerves Ganglion ACh ACh SA NE ACh AV NE NE ACh ACh Thoracic Adrenal medulla ACh ACh 90% E Most blood vessels 10% NE NE Lumbar Sacral Blood vessels of external genitalia ACh Spinal cord ACh FIGURE 18. ACh, acetylcholine; NE, norepi- nephrine; E, epinephrine; SA, sinoatrial node; AV, atrioventricular node. The central terminals for these receptors steady level of background postganglionic activity (tone). Neurons from the NTS project to the sympathetic vasoconstriction, cardiac stimulation, and RVL and nucleus ambiguus where they influence the firing adrenal medullary catecholamine secretion, all of which of sympathetic and parasympathetic nerves. This tonic activity is generated by excitatory signals from Baroreceptor Reflex Effects on Cardiac Output and Sys- the medulla oblongata.
Skeletal System: © The McGraw−Hill Anatomy order 800mg nootropil overnight delivery, Sixth Edition Introduction and the Axial Companies cheap 800mg nootropil fast delivery, 2001 Skeleton 166 Unit 4 Support and Movement Body of Radiate ligament vertebra Costotransverse ligament Articular facet Rib for tubercle of rib Transverse Lateral process costotransverse ligament Spinous process FIGURE 6. Developmental Disorders Congenital malformations account for several types of skeletal deformities. Certain bones may fail to form during osteogenesis, or they may form abnormally. They vary in severity and seem to involve both genetic and environmental factors. Nutritional and Hormonal Disorders The consequences of endocrine disorders are described in Several bone disorders result from nutritional deficiencies or chapter 14. Because hormones exert a strong influence on bone from excessive or deficient amounts of the hormones that regu- development, however, a few endocrine disorders will be briefly late bone development and growth. Hypersecretion of growth hormone from the pi- influence on bone structure and function. When there is a defi- tuitary gland leads to gigantism in young people if it begins be- ciency of this vitamin, the body is unable to metabolize calcium fore ossification of their epiphyseal plates. The bones of a child with rickets remain soft and structurally phy of the bones of the face, hands, and feet. In a child, growth weak, and bend under the weight of the body (see fig. It is teomalacia occurs most often in malnourished women who have characterized by disorganized metabolic processes within bone repeated pregnancies and who experience relatively little expo- sure to sunlight. It is marked by increasing softness of the bones, so that they become flexible and thus cause deformities. Paget’s disease: from Sir James Paget, English surgeon, 1814–99 Van De Graaff: Human IV. Skeletal System: © The McGraw−Hill Anatomy, Sixth Edition Introduction and the Axial Companies, 2001 Skeleton Chapter 6 Skeletal System: Introduction and the Axial Skeleton 167 FIGURE 6. In a bone scan, an image of an arthritic joint shows up lighter than most of a normal joint. The activity of osteoblasts and osteoclasts becomes irreg- ular, resulting in thick bony deposits in some areas of the skele- FIGURE 6. Note the loss of teeth and the de- generation of bone, particularly in the facial region.
The glucocorticoid hormones buy generic nootropil 800mg line, cortisol and corticos- Medulla: 10–20% terone cheap 800mg nootropil visa, play essential roles in adjusting the metabolism of carbohydrates, lipids, and proteins in liver, muscle, and adi- pose tissues during fasting, which assures an adequate sup- ply of glucose and fatty acids for energy metabolism de- spite the absence of food. The mineralocorticoid hormone aldosterone, another steroid hormone produced by the ad- renal cortex, stimulates the kidneys to conserve sodium Catecholamines and, hence, body fluid volume. The glucocorticoids also enable the body to cope with Androgens physical and emotional traumas or stresses. The physiological importance of this action of the glucocorticoids is empha- Cortisol sized by the fact that adrenalectomized animals lose their ability to cope with physical or emotional stresses. Even when Aldosterone given an appropriate diet to prevent blood glucose and body sodium depletion, an adrenalectomized animal may die when exposed to traumas that are not fatal to normal animals. These hormones are the catecholamines, ep- androgen dehydroepiandrosterone, which is related chem- inephrine and norepinephrine, which have widespread ically to the male sex hormone testosterone. The molecu- effects on the cardiovascular system and muscular system lar structures of these hormones are shown in Figure 34. Many small arteries branch from the aorta and renal arteries and enter the cortex. These vessels give rise to capillaries that course radially through the cortex and ter- FUNCTIONAL ANATOMY OF THE minate in venous sinuses in the zona reticularis and adrenal ADRENAL GLAND medulla; therefore, the hormones produced by the cells of the cortex have ready access to the circulation. The human adrenal glands are paired, pyramid-shaped or- The cells of the adrenal cortex contain abundant lipid gans located on the upper poles of each kidney. This stored lipid is functionally significant be- renal gland is actually a composite of two separate en- cause cholesterol esters present in the droplets are an im- docrine organs, one inside the other, each secreting portant source of the cholesterol used as a precursor for the separate hormones and each regulated by different mech- synthesis of steroid hormones. The outer portion or cortex of the adrenal gland completely surrounds the inner portion or medulla and makes up most of the gland. During embryonic develop- The Adrenal Medulla Is a Modified ment, the cortex forms from mesoderm; the medulla arises Sympathetic Ganglion from neural ectoderm. The adrenal medulla can be considered a modified sympa- thetic ganglion. The medulla consists of clumps and strands The Adrenal Cortex Consists of of chromaffin cells interspersed with venous sinuses. Chro- Three Distinct Zones maffin cells, like the modified postganglionic neurons that receive sympathetic preganglionic cholinergic innervation In the adult human, the adrenal cortex consists of three his- from the splanchnic nerves, produce catecholamine hor- tologically distinct zones or layers (Fig.
The horizontal canals also lie in a com- anterior vertical canals are each at approximately 45 to the mon plane 800mg nootropil. Near its junction with the utricle safe 800mg nootropil, each canal has a Thus, the anterior canal on one side lies in a plane parallel swollen portion called the ampulla. Each ampulla contains a crista ampullaris, the sensory structure for that semicir- cular canal; it is composed of hair cells and supporting cells encapsulated by a cupula, a gelatinous mass (Fig. The cupula extends to the top of the ampulla and is moved back and forth by movements of the endolymph in the canal. This movement is sensed by displacement of the stereocilia of the hair cells. These cells are much like those of the organ of Corti, except that at the “tall” end of the stereocilia array there is one larger cilium, the kinocilium. When the stereocilia are bent toward the kinocilium, the frequency of action potentials in the afferent neurons leaving the am- pulla increases; bending in the other direction decreases the action potential frequency. The role of the semicircular canals in sensing rotary ac- celeration is shown on the left side of Figure 4. The mechanisms linking stereocilia deflection to receptor po- The vestibular apparatus in the bony tentials and action potential generation are quite similar to FIGURE 4. Because of the inertia of the canals sense rotary acceleration and motion, while the utricle and endolymph in the canals, when the position of the head is saccule sense linear acceleration and static position. The vestibular apparatus is an important component in several reflexes that serve to orient the body in space and maintain that orientation. Integrated responses to Slow eye Head rotation movements Slow movement FIGURE 4. A, The crista ampularis contains the hair (receptor) cells, and the whole structure is deflected by mo- tion of the endolymph.
