Heal your Adrenals with this Easy Program
Although it was originally thought that the sole locus of hypocretin production was in hypothalamus, some of the peptide may be produced in testis.32'38 Whether the hypocretin apparently produced in testis, or peptide produced in brain, gains access to the general circulation in sufficient amounts to act as a true hormone is unknown. However, hypocretin receptors are present in a variety of peripheral tissues, including the adrenal gland.33'42-45 In vitro studies have demonstrated significant actions of the hypocretins on adrenal steroid and catecholamine release. Cultured rat zona fasciculata and reticularis cells released increased amounts of corticosterone under basal, but not stimulated conditions.46 Orexin A also increased cAMP formation in these cells and the effect on corticosterone release was blocked by a protein kinase A inhibitor. No significant effects of orexin on basal or agonist stimulated aldosterone secretion were observed in zona glomerulosa cell cultures. These...
On this basis, Selye stated that there is a nonspecific response of the body to readjust itself following any demand made upon it. A rise in the plasma glucocorticoid levels results from the demands of the stressors. Selye termed this nonspecific response the general adaptation syndrome (GAS). Stress, in other words, produces GAS. There are three stages in the response to stress (1) the alarm reaction, when the adrenal glands are activated (2) the stage of resistance, in which readjustment occurs and (3) if the readjustment is not complete, the stage of exhaustion, which may lead to sickness and possibly death.
An adrenal gland sits above each kidney, just below the middle of your back. Functionally and anatomically, each adrenal gland consists of a gland within a gland (Figure 42.10). The core, called the adrenal medulla, produces the hormone epinephrine (also known as adrenaline) and, to a lesser degree, norepinephrine (or noradrenaline), which also acts as a neurotransmitter in the nervous system . Surrounding the medulla is the adrenal cortex, which produces other hormones. The medulla develops from nervous tissue and is under the control of the nervous system the cortex is under hormonal control, largely by adrenocorticotropin (ACTH) from the anterior pituitary. Adrenal gland Adrenal gland 42.10 The Adrenal Gland Has an Outer and an Inner Portion An adrenal gland,consisting of an outer cortex and an inner medulla, sits on top of each kidney.The medulla and the cortex produce different hormones. 42.10 The Adrenal Gland Has an Outer and an Inner Portion An adrenal gland,consisting of an...
The human adrenal glands are paired, pyramid-shaped organs located on the upper poles of each kidney. The adrenal gland is actually a composite of two separate endocrine organs, one inside the other, each secreting separate hormones and each regulated by different mechanisms. 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 development, the cortex forms from mesoderm,- the medulla arises from neural ectoderm.
The adrenal glands, located atop each kidney, are divided into two distinct regions an outer cortex and an inner medulla (Fig. 16-4). The hormones produced by this gland are involved in the body's response to stress. The cortex produces steroid hormones, cortisol, aldosterone, and small amounts of sex hormones. Cortisol (hydrocortisone) mobilizes reserves of fats and carbohydrates to increase the levels of these nutrients in the blood. It also acts to reduce inflammation and is used clinically for this purpose. Aldos-terone acts on the kidneys to conserve sodium and water while eliminating potassium. The adrenal cortex also produces small amounts of sex hormones, mainly testosterone, but their importance is not well understood. The medulla of the adrenal gland produces two similar hormones, epinephrine (adrenaline) and norepi-nephrine (noradrenaline). These are released in response to stress and work with the nervous system to help the body meet challenges.
The adrenal glands are paired organs that cap the superior borders of the kidneys (fig. 11.18). Each adrenal consists of an outer cortex and inner medulla that function as separate glands. The differences in function of the adrenal cortex and medulla are related to the differences in their embryonic derivation. The adrenal medulla is derived from embryonic neural crest ectoderm (the same tissue that produces the sympathetic Figure 11.18 The structure of the adrenal gland, showing the three zones of the adrenal cortex. The zona glomerulosa secretes the mineralocorticoids (including aldosterone), whereas the other two zones secrete the glucocorticoids (including cortisol).
The next hormones to become deficient are usually the gonadotropins. Prepubertal children have no effects from gonadotropin deficiency, but adults develop oligoamenorrhea, impotence, and or infertility. Deficiencies of TSH, which leads to hypothyroidism, and ACTH, which leads to hypoadrenalism, are less common, even with large tumors. Deficiency of prolactin (PRL) is also uncommon and only presents in the postpartum period as a failure to lactate. Diabetes insipi- The clinical presentation of a patient with hypopituitarism is nonspecific and thus may lead to confusion. Many of the symptoms of hypopituitarism are vague, and patients can be misdiagnosed with chronic fatigue or psychiatric illness before the true diagnosis is known. In addition, symptoms of one hormone deficiency may mask those of another hormone deficiency. For example, weight gain is expected with hypothyroidism and weight loss with hypoadrenalism. If a patient has both TSH and ACTH deficiencies, weight may be...
That male rats in the chronic stage of infection with Seoul virus were more likely to attack intruders and they spent more time fighting with them than did uninfected males. Furthermore, aggressive males had more virus in tissues (including testes and adrenal glands) than did less aggressive males.
Many mollusks have neurons resembling neurosecretory cells that change their apparent secretory activity with conditions such as reproductive state. In a few cases, evidence has been found for neurosecretory control of reproduction, water balance, or heart function. Cephalopods such as squid, however, are one of the few classes of animals that possess endocrine glands. The cepha-lopod brain is connected to the optic lobes by short optic stalks bearing optic glands. As the animal matures, the size of these glands increases. These glands function in the control of reproductive development. Glands on the gills, called mesodermal branchial glands, are also endocrine organs and are thought to function similarly to vertebrate adrenal glands.
Steroid hormones, also produced in the adrenal glands, stimulate the production of glucose from noncarbohydrate molecules (gluconeogenesis). The stimulus for this is prolonged stress, for example, starvation. These glucocorticoids, such as cortisol and corticosterone, evolved early and are very important in combating stresses resulting from migration among birds and even fish. The pancreatic hormones insulin and glucagon also effect energy metabolism. These two proteins regulate blood sugar, fat, and protein levels. After eating, insulin stimulates transport of these molecules into liver, fat, and muscle cells and then stimulates the incorporation of the simple molecules, such as glucose, amino acids, and fatty acids, into larger storage molecules, such as glycogen, protein, and fats. Glucagon has opposite actions. After a prolonged period without food intake, glucagon stimulates breakdown of complex molecules, such as glyco-gen and fats, into simple...
Has been identified in 7.5 of normal testes by Dahl et al. (44). In the embryological phase, the adrenal glands develop in the immediate vicinity of the gonads. Aberrant adrenal tissue may descend with the testis or ovary along the course of their supplying arteries and end up in the testes, celiac plexus, broad ligament, or ovary (44-48). The aberrant adrenal cells are believed to retain their potential for glucocorticoid production and to respond with hyperplasia to increased ACTH stimulation. The testicular tumors in males with CAH are, therefore, often called adrenal rest tumors.
The amount of brown fat in the body is greatest at the time of birth. Brown fat is the major site for thermogenesis (heat production) in the newborn, and is especially prominent around the kidneys and adrenal glands. Smaller amounts are also found around the blood vessels of the chest and neck. In response to regulation by thyroid hormone (see chapter 11) and norepinephrine from sympathetic nerves (see chapter 9), brown fat produces a unique
By means of their diffusing subunits, G proteins can either activate or inhibit an effector. An example of an activating response involves the receptor for epinephrine (adrenaline), hormone made by the adrenal gland in response to stress or heavy exercise. In heart muscle, this hormone binds to its G protein-linked receptor, activating a G protein . The GTP-bound subunit then activates a membrane-bound enzyme to produce a small molecule, cyclic AMP (see below), that has many effects on the cell, including glucose mobilization for energy and muscle contraction.
Physiological characteristics of subordinates that distinguish them from dominants include differences in measurements of adrenal function. Following dexamethasone suppression, the adrenal glands of subordinate females hypersecrete cortisol in response to an adrenocorticotropic hormone challenge, and are also relatively insensitive to cortisol
In other tissues, the essential product of the pentose phosphate pathway is not the pentoses but the electron donor NADPH, needed for reductive biosynthesis or to counter the damaging effects of oxygen radicals. Tissues that carry out extensive fatty acid synthesis (liver, adipose, lactating mammary gland) or very active synthesis of cholesterol and steroid hormones (liver, adrenal gland, gonads) require the NADPH provided by the pathway. Erythrocytes and the cells of the lens and cornea are directly exposed to oxygen and thus to the damaging free radicals generated by oxygen.
Hormones produced by different glands can have similar physiological effects. Both the adrenal glands and the testes produce androgens (masculinizing hormones). Sexually experienced male cats do not lose their sex drive if castrated, and researchers do not have a satisfactory answer as to why this occurs. Perhaps the adrenal hormones are sufficient to maintain established feline male sexual behavior but not sufficient to initiate it in inexperienced cats. The ablation of the adrenal glands, however, has severe consequences in terms of electrolyte and blood glucose imbalances that are life threatening. Replacement of ablated endocrine tissue can reinstate normal function. If
Several other endocrine glands provide good examples of the importance of this system in the overall functioning of the body. The thyroid gland secretes thyroxin, which regulates metabolism and influences psychological processes such as motivation and mood. The adrenal glands secrete adrenaline and noradrenaline, hormones that operate antagonistically to regulate mood, emotion, blood pressure and sugar level, and the distribution of blood between muscles and internal organs. More generally, these hormones are described as helping the organism prepare for emergencies and cope with stress. The gonads, or sex glands, secrete hormones concerned with sexual development, activity, and receptivity.
We propose the following model for the 02 signaling pathway in AMC (Fig. 5). During hypoxia, 02 availability is decreased and ROS generation at a critical site of the proximal ETC is reduced. The key ROS may be H202, which is generated in the mitochondria by the dismutation of 02 , is freely diffusible, and can be long-lived depending on catalase levels in the cell. The combined inhibition of BK, SK, and Kv channels leads to or enhances membrane depolarization and action potential broadening, increasing Ca2+ influxthrough nifedipine-sensitive L-type Ca2+ channels and CA secretion. Although controversial, it appears that the ability of AMC to directly respond to hypoxia disappears along a time course similar to the maturation of sympathetic innervation to the adrenal gland.
In summary, the central nervous system provides inputs in terms of registrations by the senses, modified by experience and coping ability, and the integrated resulting signals transferred to the hypothalamus. These afferent signals are balanced by endocrine feedback regulation, mediated via glucocorticoid receptors (GR) in the hippocampus and the amygdala (24-26). Feedback information allows the HPA axis to adjust appropriately the cortisol secretion from the adrenals.
Under certain stressful situations, the brain sends impulses to the two small adrenal glands that lie on top of the kidneys. They produce two chemicals called adrenaline and noradrenaline, which affect the body in various ways. These chemicals are released into the bloodstream to help the body react to stressful and potentially dangerous situations. This is often called the fight-and-flight response. The heart rate and blood pressure increase, the breathing gets faster and deeper, sugar is released into the blood from the liver providing energy and fuel for the muscles, and the person feels sweaty and nervous. These chemicals can be measured in the blood. The brain senses, feels, hears, or sees the danger and the adrenal glands produce the chemicals that enable the person to either fight or flee.
The liver plays an important role in cholesterol homeostasis. Liver cholesterol is derived from both de novo synthesis and the lipoproteins taken up by the liver. Hepatic cholesterol can be used in the formation of bile acids, biliary cholesterol secretion, the synthesis of VLDLs, and the synthesis of liver membranes. Because the absorption of biliary cholesterol and bile acids by the GI tract is incomplete, this method of eliminating cholesterol from the body is essential and efficient. However, patients with high plasma cholesterol levels might be given additional drugs, such as statins, to lower their plasma cholesterol levels. Statins act by inhibiting enzymes that play an essential role in cholesterol synthesis. VLDLs secreted by the liver provide cholesterol to organs that need it for the synthesis of steroid hormones (e.g., the adrenal glands, ovaries, and testes).
The most important extracellular buffer is the bicarbonate buffer system discussed above. This system is aided directly by a second line of defense against pH disturbances. This is called physiological buffering. Physiological buffering refers to the fact that the supply of the most important components of the bicarbonate buffer system, carbon dioxide and bicarbonate, can be controlled. The organs responsible for this control are the lungs (carbon dioxide) and kidneys (bicarbonate). For example, during exercise, the buildup of lactic acid consumes bicarbonate (HCO3) and lowers pH. This is called a metabolic acidosis. The low pH stimulates the rate of breathing, which in turn results in increased elimination of carbon dioxide by the lungs. This lowers the partial pressure (concentration) of carbon dioxide in the blood, reducing the amount of carbonic acid (H2CO3) that can dissociate to form H+. The reduction of carbon dioxide is called a respiratory alkalosis. This respiratory...
HDL may be taken up in the liver by receptor-mediated endocytosis, but at least some of the cholesterol in HDL is delivered to other tissues by a novel mechanism. HDL can bind to plasma membrane receptor proteins called SR-BI in hepatic and steroidogenic tissues such as the adrenal gland. These receptors mediate not endocytosis but a partial and selective transfer of cholesterol and other lipids in HDL into the cell. Depleted HDL then dissociates to recirculate in the bloodstream and extract more lipids from chylomicron and VLDL remnants. Depleted HDL can also pick up cholesterol stored in extrahepatic tissues and carry it to the liver, in reverse cholesterol transport pathways (Fig. 21-40). In one reverse transport path, interaction of nascent HDL with SR-BI receptors in cholesterol-rich cells triggers passive movement of cholesterol from the cell surface into HDL, which then carries it back to the liver. In a second pathway, apoA-I in depleted HDL in-
Adrenal insufficiency may be caused by destruction of the adrenal cortex (primary adrenal insufficiency), low pituitary ACTH secretion (secondary adrenal insufficiency), or deficient hypothalamic release of CRH (tertiary adrenal insufficiency). Addison's disease (primary adrenal insufficiency) results from the destruction of the adrenal gland by microorganisms or autoimmune disease. When Addison's first described primary adrenal insufficiency in the mid-1800s, bilateral adrenal destruction by tuberculosis was the most common cause of the disease. Today, autoimmune destruction accounts for 70 to 90 of all cases, with the remainder the resulting from infection, cancer, or adrenal hemorrhage. The prevalence of primary adrenal insufficiency is about 40 to 110 cases per 1 million adults, with an incidence of about 6 cases per 1 million adults per year. Antibodies that react with all three zones of the adrenal cortex have been identified in autoimmune adrenalitis and are more common in...
The adrenal gland lies on the superior surface of each kidney. It is a double organ composed of an outer cortex and an inner medulla. In response to ACTH secreted by the anterior pituitary, the adrenal cortex secretes several hormones (the glucocorticoids, the mineralocorticoids, and small amounts of sex hormones).
The earliest water-balance problem that the vertebrates faced in their evolutionary history was an excess of fresh water and a scarcity of sodium. The hormone aldosterone evolved in the fishes to cope with this. Aldosterone is secreted by the adrenal gland and increases the reabsorption
ANP inhibits aldosterone synthesis and release from adrenal glomerulosa cells (3,217) suggesting that this ANP action could be physiologically important, which probably accounts for natriuretic and diuretic effects. The established biochemical and cellular effects of ANP within adrenal glomerulosa cells include the activation of GC activity and potassium channel conductance, whereas T-type calcium channels conductance and adenylyl cyclase activity are suppressed (83). The NPRA antagonist HS-142-1 eliminated ANP effects to suppress the aldosterone synthesis and to elevate cGMP production in bovine adrenal glomerulosa cells, providing additional evidence for the involvement of NPRA in the inhibition of ANP-dependent aldosterone secretion (218). However, the correlative evidence that cGMP suppresses the aldosterone secretion was challenged by the observation that aldosterone release was maintained in the presence of cGMP analogs such as dibutyryl-cGMP or 8-bromo-cGMP (3,219). Further...
The medicinal use of corticosteroids was stimulated by reports of the dramatic effects of cortisone on patients suffering from rheumatoid arthritis in the late 1940s and early 1950s. The cortisone employed was isolated from the adrenal glands of cattle, and later was produced semi-synthetically by a laborious process from deoxycholic acid (see page 260) isolated from ox bile and necessitating over 30 chemical steps. Increased demand for cortisone and hydrocortisone (cortisol) (it had been shown that cortisone was reduced in the liver to hydrocortisone as the active agent) led to exploitation of alternative raw materials, particularly plant sterols and saponins. A major difficulty in any semi-synthetic conversion was the need to provide the 11 -hydroxyl group which was essential for glucocorticoid activity.
In resistant cases where the combination of pituitary surgery and irradiation have failed to control CD and or medical therapy is poorly tolerated, bilateral adrenalectomy should be considered. Provided all adrenal tissue is removed, satisfactory reduction in the circulating cortisol level is seen. This procedure is frequently performed by minimally invasive surgery or laparoscopy, but care is required because the adrenal glands are often large, vascular, and friable in CD. The presence of continuing cortisol excess after adrenalectomy raises the possibility of the presence of adrenal rests.
The regulatory molecules epinephrine, norepinephrine, dopamine, and serotonin are in the chemical family known as monoamines. Serotonin is derived from the amino acid tryptophan. Epinephrine, norepinephrine, and dopamine are derived from the amino acid tyrosine and form a subfamily of monoamines called the catecholamines (see fig. 9.8, p. 229). Epinephrine (also called adrenaline) is a hormone secreted by the adrenal gland, not a neurotransmitter, while the closely related norepinephrine functions both as a hormone and a neurotransmitter.
A large number of steroid hormones have been isolated and characterized from the adrenal glands. Since they are produced by the adrenal cortex, the outer part of the adrenal glands near the kidneys, they are termed adrenocortical hormones or corticosteroids*. They contain a pregnane C21 skeleton and fall into two main activity groups, the glucocorticoids and the mineralocorticoids, although it is difficult to separate entirely the two types of activity in one molecule. Glucocor-ticoids are concerned with the synthesis of carbohydrate from protein, and deposition of glycogen in the liver. They also play an important role
The hypocretin system is highly expressed in the adrenal gland and shows a species-specific pattern of expression. Thus, while no expression of prepro-Hcrt has been detected in the rat adrenal gland,69,70 immunoreactivity for prepro-Hcrt and Hcrt1 has been described in human adrenal gland.71,72 Hypocretin receptors have been described in the adrenal cortex and or in the adrenal medulla of rat,66,70,73 pig74 and human71,75-77 (Fig. 1C and 1D).
Important components of the mesodermal germ layer are paraxial, intermediate, and lateral plate mesoderm. Paraxial mesoderm forms somito-meres, which give rise to mesenchyme of the head and organize into somites in occipital and caudal segments. Somites give rise to the myotome (muscle tissue), sclerotome (cartilage and bone), and dermatome (subcutaneous tissue of the skin), which are all supporting tissues of the body. Signals for somite differentiation are derived from surrounding structures, including the notochord, neural tube, and epidermis. The notochord and floor plate of the neural tube secrete Sonic hedgehog, which induces the sclerotome. WNT proteins from the dorsal neural tube cause the dorsomedial portion of the somite to form epaxial musculature, while BMP-4, FGFs from the lateral plate mesoderm, and WNTs from the epidermis cause the dorsolateral portion to form limb and body wall musculature. The dorsal midportion of the somite becomes dermis under the influence of...
Attempts are also being made to restore function to damaged or diseased brains by the implantation of precursor cells that will develop into new neurons that will replace missing neurotransmitters or neurotropic factors. Alternatively, pieces of fetal brain or tissues from the patient that produce the needed neurotransmitters or growth factors are implanted. For example, the adrenal medulla, which is part of the adrenal glands, synthesizes and secretes chemicals similar to some of the neurotransmitters found in the brain. When pieces of a patient's own adrenal medulla are inserted into damaged parts of the brain, the pieces continue to secrete these chemicals and provide the missing neurotransmitters.
Pink to brown or black, and haemangiomas (Campbell de Morgan spots) are so common that they could be considered normal changes. The presence of striae requires explanation. Any abnormality of the skin should be noted, including surgical scars, and the nature of the surgery undertaken should be identified. Laparoscopic incisions are usually immediately below the umbilicus and may be difficult to see. The common sites of surgical incisions are shown in Table 5.26 and illustrated in Figure 5.7. Other transverse incisions are used for access to the aorta, kidneys, adrenals, ureters, sympathetic chain or stoma closures. The common types of stoma arc illustrated in Figure 5.8. The effluent from a colostomy is solid with a faecal odour in an ileostomy there is a fluid, odourless effluent.
As well as being controlled by hypothalamic releasing and release-inhibiting hormones, the endocrine cells of the anterior pituitary are also under negative feedback control by the hormones of the target glands they stimulate (Figure 42.8). For example, the hormone cortisol, produced by the adrenal gland in response to adrenocorticotropin secreted by the an
Anterior pituitary secretion of ACTH, TSH, and the gonadotropins (FSH and LH) is controlled by negative feedback inhibition from the target gland hormones. Secretion of ACTH is inhibited by a rise in corticosteroid secretion, for example, and TSH is inhibited by a rise in the secretion of thyroxine from the thyroid. These negative feedback relationships are easily demonstrated by removal of the target glands. Castration (surgical removal of the gonads), for example, produces a rise in the secretion of FSH and LH. In a similar manner, removal of the adrenals or the thyroid results in an abnormal increase in ACTH or TSH secretion from the anterior pituitary.
The negative-feedback actions of glucocorticoids are essential for the normal operation of the hypothalamic-pitu-itary-adrenal axis. This relationship is vividly illustrated by the disturbances that occur when blood glucocorticoid levels are changed drastically by disease or glucocorticoid administration. For example, if an individual's adrenal glands have been surgically removed or damaged by disease (e.g., Addison's disease), the resulting lack of glucocorticoids allows corticotrophs to secrete large amounts of ACTH. As noted earlier, this response may result in hyperpigmenta-tion as a result of the melanocyte-stimulating activity of ACTH. Individuals with glucocorticoid deficiency caused by inherited genetic defects affecting enzymes involved in steroid hormone synthesis by the adrenal cortex have high blood ACTH levels from the absence of the lack of the negative-feedback effects of glucocorticoids on ACTH secretion. Because a high blood concentration of ACTH causes hypertrophy of...
In the brain, adrenals, heart, vasculature, and kidney, and serve to regulate blood pressure and fluid and electrolyte balance. In the heart, the highest density of AT1 is found in the conducting system (43). Punctate AT1 binding is found in the epicardium surrounding the atria, with low binding seen throughout the atrial and ventricular myocardium (44). Moreover, AT1 in the vasculature, including the aorta, pulmonary and mesenteric arteries, are present in high levels on VSMC, with low levels in the adventitia (45). Virtually all of the known biological actions of Ang II are mediated by ATp including the elevation of blood pressure, vasoconstriction, increase in cardiac contractility, release of aldo-sterone and vasopressin, renal tubular sodium reabsorption, stimulation of sympathetic transmission, and cellular growth (46). In addition, a recent in vitro and in vivo evidence supports the notion that Ang II, mediated by ATp may participate directly in the pathogenesis of various...
The first two enzymes in steroid synthesis (30-hydroxysteroid dehydrogenase and 17a-hydroxylase 17,20-lyase) and the intracellular cholesterol transport protein (StAR), are present in both adrenals and gonads. A deficiency of these enzymes or in the StAR protein leads to cortisol and aldosterone deficiency and insufficient gonadal production of sex steroids. In the male patient, this results in prenatal hypovirilization, depending on the degree of the enzyme deficiency, varying from hypospadias to inter-sex conditions.
Once the diagnosis of endogenous CS has been established, the next challenge is to establish its specific cause (7,14). Generally, a relatively acute onset of symptoms with rapid progression and associated hypokalemic alkalosis point toward an ectopic ACTH source. Accurate differential diagnosis, however, can only be achieved by the combination of dynamic endocrine testing of the integrity of the feedback regulation of the hypothalamic-pituitary-adrenal (HPA) axis, and imaging techniques used mainly to examine the size and shape of the pituitary and adrenal glands and to localize ectopic ACTH- or CRH-secreting tumors (Fig. 2). It is essential that dynamic adrenal testing is performed when the patient is clearly hypercortisolemic. Hypercortisolemia needs to be documented always at the time of testing to avoid mistakes. To that purpose, all adrenal blocking agents should be discontinued for at least 4 wk before testing. Morning measurement of plasma ACTH concentrations simultaneously...
Maternal blood, where it causes the synthesis of another prostaglandin. The strongest support for this conclusion comes from experiments in which the adrenal glands were removed from fetal goats the result of such in utero surgery is significantly delayed parturition (birth). This uterine prostaglandin intensifies the uterine contractions to initiate labor and thus parturition.
Not only are there neuropathological changes in MLD, but also visceral abnormalities. Outside the CNS, metachromatic material is found in the liver, spleen and lymph nodes, gallbladder, pancreas, kidneys, adrenal glands, ovaries, ganglion cells of the retina, and leukocytes of peripheral blood and bone marrow. Storage in these organs is limited to certain cell types. Visceral accumulations are not accompanied by further morphological changes or obvious clinical dysfunction. Although MLD becomes manifest only with neurological abnormalities, it is clear that it is a generalized metabolic disorder.
Frightened by a false alarm, an animal may jump and run as a direct consequence of nervous system activity, but even after it recognizes that there is no real threat, it will be keyed-up. This is a consequence of hormonal activity Fright triggered the release of epinephrine (adrenaline) and norepinephrine from the adrenal glands. These hormones cause increased cardiac output increased blood supply to the brain, heart, and muscles decreased blood flow to the digestive tract dilation of airways to breath more efficiently and a significant increase in metabolic rate.
A reasonable initial hypothesis is that the baby has a form of congenital adrenal hyperplasia. The virilization (appearance of pubic hair) suggests the presence of excess androgen production by the adrenal gland. The hyponatremia, hyperkalemia, and volume depletion suggest a salt wasting syndrome. corticoids and mineralocorticoids. Glucocorticoids would replace the missing cortisol and also suppress ACTH secretion. With less ACTH stimulation of steroid production from the adrenal gland, the hyperandrogenemia should subside. Mineralocorticoids are given to treat the salt wasting that occurs in the absence of aldosterone.
ANP affects blood pressure directly through its natriuretic, diuretic, and vasodilatory actions (187). It also affects blood pressure indirectly, for example, by inhibiting the RAAS, which is known to cause hypertension and cardiovascular diseases, if excessively stimulated (266). Genetic defects that reduce the activity or influence the ANP-NPRA system greatly contribute to the development of hypertension. The mechanistic role of ANP-NPRA system in counteracting the pathophysiology of hypertension is not well understood. Although the expression of ANP and BNP is markedly increased in patients with hypertrophic or failing heart, it is unclear if the NP system is activated to play a protective role by reducing the detrimental effects of high blood pressure caused by sodium retention and fluid volume, inhibiting the RAAS, or it is simply a consequence of the hypertrophic changes occurring in heart. Recent studies indicated that intrarenal renin in newborn Npr1 homozygous null mutant...
During the past decade dopamine has been shown to be an active modulator of sodium balance, by actions in the adrenal gland (27,28), intestinal (29-31) and renal epithelia (11,14-26,33-82), and sympathetic nervous system (83). Although the dopaminergic system is active in various anatomic locations, the concentrations of dopamine found circulating in the blood (picomolar) are not high enough to activate the dopamine receptor because nanomolar concentrations are required for receptor activation. However, high nanomolar concentrations of dopamine can be generated locally by the conversion of L-DOPA found in the circulation to dopamine by L-aromatic amino acid decarboxlase found in dopamine-producing tissues (e.g., renal proximal tubule and jejunum). In the proximal tubule, dopamine does not become converted to norepinephrine (as in neurons) because renal tubules do not express dopamine -hydroxylase. Dopamine produced intracellularly is then secreted into the tubular lumen, to a greater...
The autonomic nervous system (ANS) is the division of the nervous system that controls the involuntary actions of muscles and glands (Fig. 17-6). The ANS itself has two divisions the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system motivates our response to stress, the so-called fight-or-flight response. It increases heart rate and respiration rate, stimulates the adrenal gland, and delivers more blood to skeletal muscles. The parasympathetic system returns the body to a steady state and stimulates maintenance activities, such as digestion of food. Most organs are controlled by both systems and, in general, the two systems have opposite effects on a given organ.
Indirect (endocrine) effects of testicular tumors in CAH on fertility could result from steroid secretion by the tumor, with suppression of the hypothalamic-pituitary-gonadal axis. The association between infertility, testicular adrenal rest tumors, and depressed serum LH and FSH levels in males with CAH has been described (5,6,39,43,54). However, the effect of steroid secretion by the tumor cannot be readily separated from the effect of excess steroids secreted by the adrenal glands.
Hypocretin receptors were originally - and also still very often are - thought to couple to Gq, since they strongly elevate cytosolic Ca2+ in many systems and also activate PI-PLC. However, the only studies directly addressing the G-protein coupling of hcrtr have been performed on human adrenal gland. In these studies, hcrtr-2 receptors have been seen to be capable of coupling to Gq, Gi and Gs, but not Go using the GTP-azidoanilide labeling method, while the coupling to G12 13 was not investigated.4'5 Hypocretinl-stimulated in situ GTPyS binding in the rat brain stem6'7 suggest the ability of hcrtr to couple to Gl o proteins, which are the G-proteins primarily seen with this technique. Indirect evidence of the coupling of the hcrtr to Gi o proteins has been obtained in some studies using pertussis toxin (see below).
The fetal adrenal glands are unique in both structure and function. At month 4 of gestation, they are larger than the kidneys, as a result of the development of a fetal zone that constitutes 75 to 80 of the whole gland. The outer definitive zone will form the adult adrenal cortex, whereas the deeper fetal zone involutes after birth, the reason for the involution is unknown, but it is not caused by the withdrawal of ACTH support. The fetal zone produces large amounts of DHEAS and provides androgenic precursors for estrogen synthesis by the placenta (see Fig. 39.7). The definitive zone produces cortisol, which has multiple functions during fetal life, including the promotion of pancreas and lung maturation, the induction of liver enzymes, the promotion of intestinal tract cytodifferentiation and, possibly, the initiation of labor. ACTH is the main regulator of fetal adrenal steroido-genesis, partly evidenced by the observation that anen-cephalic fetuses have low ACTH and the fetal zone...
The adrenal medulla, a neuroendocrine gland, forms the inner core of the adrenal gland situated on top of each kidney. Cells of the adrenal medulla are innervated by the lesser splanchnic nerve, which contains preganglionic sympathetic axons originating in the lower thoracic spinal cord (see Fig. 6.4). These axons pass through the paravertebral ganglia and the celiac ganglion without synapsing and terminate on the chromaffin cells of the adrenal medulla (Fig. 6.5). The chromaffin cells are modified ganglion cells that synthesize both epinephrine and norepinephrine in a ratio of about 8 1 and store them in secretory vesicles. Unlike neurons, these cells possess neither axons nor dendrites but function as neuroendocrine cells that release hormone directly into the bloodstream in response to preganglionic axon activation.
Adrenergic drugs are contraindicated in patients with known hypersensitivity. Isoproterenol is contraindicated in patients with tachyarrhythmias, tachycardia or heart block caused by digitalis toxicity, ventricular arrhythmias, and angina pectoris. Dopamine is contraindicated in those with pheochromocytoma (tumor of adrenal gland), unmanaged arrhythmias, and ventricular fibrillation. Epinephrine is contraindicated in patients with narrow-angle glaucoma, cerebral arteriosclerosis, and cardiac insufficiency. Norepinephrine and ephedrine are contraindicated in patients who are hypotensive from blood volume deficits. Midodrine is contraindicated in those with severe organic heart disease, acute renal disease, pheochromocytoma, and supine hypertension.
When the hormone epinephrine (Adrenalin) is secreted by the adrenal gland, it is delivered to all parts of the body by the cardiovascular system. Among other effects, epinephrine increases the rate of metabolism of all cells of the body. This helps to mobilize energy during a fight-or-flight stress reaction.
Considerable amount would be needed for bile production - even though greater than 80 of the bile salts are absorbed from the large intestine and re-utilized. Thus, under physiological conditions cholesterol is needed mainly in cell division (growth or replacement of desquamated cells), in the replacement of cholesterol metabolized to steroid hormones in the adrenals and other endocrine glands or catabolized to bile acids by the liver. Although sterols are present in most mammalian body tissues, the proportion of sterol ester to free sterol varies markedly. For example, blood plasma, especially that of humans, is rich in sterols and like most plasma lipids they are almost entirely found as components of the lipoproteins about 60-80 of this sterol is esterified. In the adrenals, too, where cholesterol is an important precursor of the steroid hormones, over 80 of the sterol is esterified. However, in brain and other nervous tissues, where cholesterol is a major component of myelin,...
Hcrt mRNA has not been localized in these structures to date. Hcrt mRNA was also detected in the ventricular ependymal cell lining.57 Hcrt peptides and receptors have also been reported in several peripheral tissues including plasma,58'59 sympathetic ganglia, myenteric plexus, endocrine cells of the gastrointestinal tract,60 adrenal gland,61-63 islet cells of the pancreas,60,61 and placenta.61 In the gut, the gastrin-containing endocrine cells of the stomach were Hcrtl immunoreactive64,65 and several Hcrtl-immunoreactive neurons were seen in the intestinal mucosa, a subpopulation of which also expressed serotonin.64 Hcrt mRNA was shown by RT-PCR to be expressed in the testes,63'66'67 but not in the ovaries.63 The testes also apparently contain hcrtrl mRNA.63'67 Merkel cells in the pig snout have also been reported to be Hcrt-immunoreactive.68 Expression of hcrtl mRNA was also seen in the pituitary, kidney, adrenal, thyroid, jejunum,63 olfactory epithelium,15 and Merkel cells.68 High...
Have demonstrated the importance of tissue RAS in the brain, heart, adrenal glands, vasculature, as well as in the kidney (1,24). Although every organ in the body has the elements of the RAS, the kidney is unique in having every component of the RAS with compartmentalization in the tubular and interstitial networks as well as intracellular accumulation. In addition, the kidneys, as well as the adrenal glands, have tissue concentrations of Ang II much greater than can be explained by the concentrations delivered by the arterial blood flow (25-28). There is substantial evidence that the major fraction of Ang II present in renal tissues is generated locally from the AGT delivered to the kidney and from the AGT locally produced by proximal tubule cells. Ang I delivered to the kidney can also be converted to Ang II (29,30). Renin secreted by the juxtaglomerular apparatus (JGA) cells and delivered to the renal interstitium and vascular compartment also provides a pathway for the local...
Patients are usually sent home after pituitary surgery on replacement doses of hydrocortisone (15-30 mg d according to protocol) or its equivalent to prevent symptomatic hypoadrenalism in case of pituitary damage. Higher doses or longer acting glucocorticoids are inappropriate, because they will lead to adrenal suppression. Six weeks after surgery, patients should be instructed to withold their hydrocortisone dose on the day of testing, and a short ACTH stimulation test should be performed. Waiting 6 wk means that the adrenal glands will atrophy if there is ACTH deficiency, and an ACTH stimulation test will show a blunted cortisol response. In the past, high-dose ACTH (250 g) was used in this test, but recent publications suggest that low-dose (1 g) tests are more accurate in diagnosing ACTH deficiency (36). A cortisol response of
After insufflation and trocar positioning, the laparoscopic pointer with the Doppler device and navigation system is only used in the retroperitoneum. We do not use the navigation system and pointer for organs that are moved or extensively shifted due to insufflation since, in these cases (laparoscopic adrenalectomies, i.e., removal of the adrenal gland), we use preoperatively acquired images for guidance. The accuracy of the rigid LNP is better than 1.5 mm. This means that keeping the tip of the pointer steady and moving the shaft about, results in a maximum scatter of the tip position of 1.5 mm.
The HPA axis is the endocrine axis in which hypocretins play their most extensive role in fact the rat adrenal gland was the first peripheral organ in which Hcrtrs were detected.70 Additional papers have demonstrated the existence of hypocretin receptors at all levels of the HPA. Thus, immunohistochemical studies have revealed the anatomical contact between hypocretin terminals and corticotropin-releasing hormone (CRH) cells in the parvocellular part of the paraventricular hypothalamic nucleus,38'57 which express Hcrtrl.61 Moreover, in the human pituitary there is abundant expression of Hcrtr2 in corticotrope cells,68 suggesting direct hypocretin actions, and in the rat adenohypophysis all the corticotrope cells present Hcrt2 immunoreactivity,67 suggesting a paracrine role of hypocretins in these cells.
The brain trigger the secretion of ADH. This small peptide then stimulates thirst and water retention in the kidneys. In amphibians, it also stimulates water absorption by the skin and urinary bladder. A steroid hormone produced in the adrenal glands called aldosterone stimulates the kidney and large intestine to conserve sodium. The kidneys also excrete increased amounts of potassium in response to aldosterone. Aldosterone secretion is stimulated by angiotensin II. When blood sodium levels decrease, there is a consequent loss of water and thus body fluid volume. Pressure receptors in the kidneys trigger the release of renin, which initiates a complex series of enzymatic reactions in the
Because ACTH stimulates the release of glucocorticoids from the adrenal gland, adverse reactions seen with the administration of this hormone are similar to those seen with the glucocorticoids (see Display 50-2) and affect many body systems. The most common adverse reactions include
Steroids Steroids have a distinctly different structure from that of the other subclasses of lipid molecules. Four interconnected rings of carbon atoms form the skeleton of all steroids (Figure 2-12). A few hy-droxyl groups, which are polar, may be attached to this ring structure, but they are not numerous enough to make a steroid water-soluble. Examples of steroids are cholesterol, cortisol from the adrenal glands, and female (estrogen) and male (testosterone) sex hormones secreted by the gonads.
Drug names are derived in a variety of ways. Some are named for their origin. Adrenaline, for example, is named for its source, the adrenal gland. Even its generic name, epinephrine, informs us that it comes from the gland that is above the kidney. Pitocin, a drug used to induce labor, is named for its source, the pituitary gland, combined with the chemical name of the hormone, oxytocin. Botox, currently injected into the skin for cosmetic removal of wrinkles, is the toxin from the organism that causes botulism, a type of food poisoning. Aspirin (an anti-inflammatory agent), Taxol (an antitumor agent), digitalis (used to treat heart failure), and atropine (a smooth muscle relaxant) are all named for the
11-Hydroxylated steroids, like 21-deoxycortisol (21-DF), 21-deoxycorticosterone (21-DB), and 1ip-hydroxy-A4-androstenedione (11P-OHA), have been demonstrated in vitro (37,38), as well as in vivo (37,39,40). 11-Hydroxylase activity is usually restricted to the adrenal gland. Clark et al. demonstrated 11-hydroxylase activity in vitro in a testicular tumor from a patient with salt-wasting CAH (38). That study identified abundant angiotensin II receptors but no gonadotropin receptors in tumor membranes. In vivo, 11-hydroxylase activity was demonstrated by testicular vein sampling by Blumberg-Tick et al. (40). Combes-Moukhovsky et al. showed that stimulation with human chorionic gonadotropin (hCG) increased secretion of 11-hydroxylated steroids (39). In humans, LH hCG receptors have been found not only in the testes but also in the normal adrenal cortex (41).
Circadian rhythms of several physiological variables in a human subject with room lights on (open bars at top) for 16 h and off (black bars at top) for 8 h. As is usual in dealing with rhythms, we have used a 24-h clock in which both 0 and 24 designate midnight and 12 designates noon. Cortisol is a hormone secreted by the adrenal glands.
Cancer is also predicted by increased proportions of the central fat stores. This was first reported in a small number of endometrial carcinomas (57), and has subsequently been reported also for breast carcinoma (58) and confirmed in a larger study of endometrial carcinomas (59). Since these reports seem to suggest that the carcinomas predicted are localized to tissues which are sensitive to sex steroid hormones, one might speculate that the abnormalities of steroid hormone secretion found in abdominal obesity are also involved in this problem. Elevated androgens are closely associated with centralization of fat in women (21,60) as discussed in a preceding section, and probably originate from the adrenals as a consequence of a central drive of the HPA axis. Such abnormalities indicate disturbed secretions of sex steroid hormones which in an unknown way might be associated with these endocrine dependent carcinomas.
Enlargement of many internal organs is found, including liver, spleen, heart, pancreas, thymus, thyroid, and kidneys. Marked vacuolar storage is present in hepatocytes, Kupffer cells, and bile duct epithelium. The gall bladder may be strawberry-like and non-functioning and the adrenals may be small and at-rophic. Granulovacuolar storage is seen in almost all organs, including kidney, spleen, lymph nodes, lungs, heart, endocrine glands, and sweat glands. In addition, vacuoles are present in vascular endothelial cells, fibroblasts, bone marrow cells, and circulating lymphocytes.
Lactogenesis (milk production) does not begin until a female has produced young. During pregnancy, a complex of hormones prepares the mammary glands for milk production by promoting their growth and internal development. These hormones include prolactin from the mother's anterior pituitary gland, placental lactogen from the placenta within the uterus, and estrogen and progesterone, which are produced in the corpus luteum of the mother's ovary and in the placenta. Other hormones, including cortisol from the adrenal gland, thyroxine from the thyroid gland, and insulin from the pancreatic islets, may also be involved. Progesterone appears to participate in the induction of mammary development, but, paradoxically, it also prevents milk secretion during pregnancy.
The pituitary gland (hypophysis) is a small gland beneath the brain. It is divided into an anterior lobe (ade-nohypophysis) and a posterior lobe (neurohypophysis). Both lobes are connected to and controlled by the hypothalamus, a part of the brain. The anterior pituitary releases six hormones. One of these is growth hormone (somatotropin), which stimulates the growth of bones and acts on other tissues as well. The remainder of the pituitary hormones regulate other glands, including the thyroid, adrenals, gonads, and mammary glands (see Display 16-1). These hormones are released in response to substances (releasing hormones) that are sent to the anterior pituitary from the hypothalamus. They can be identified by the ending -tropin, as in gonadotropin. The adjective ending is -tropic.
The leading causes of acute meningitis are viruses and bacteria. The most dreaded of all is meningoccal meningitis. The presence of purpura or petechial rash on the trunk, lower extremities, mucous membranes including conjunctiva but absence in the nail beds is highly suggestive but not diagnostic of meningococcemia. Children with fulminant meningococcal septicemia may develop the Waterhouse-Friderichsen syndrome characterized by cardiovascular collapse associated with hypoadrenalism and disseminated intravascular coagulation.
Original findings were strongly influenced by a few extreme observations. It is also clear that the cortisol output is frequently normal or even low in subjects with elevated WHR (Figure 1 in reference 15). Results of other studies indicated that when the hypothalamic-pituitary-adrenal (HPA) axis, regulating cortisol secretion, was stimulated at the levels of the adrenals with adrenocorticotropic hormone (ACTH), the pituitary with corticotrophin-releasing hormone (CRH) and the hypothalamic centres by laboratory stress, the total urinary output of cortisol appeared to be elevated in subjects with high WHR (15,16). However, the challenges at the different levels of the HPA axis were performed with maximal doses of ACTH and CRH. The use of such doses provides information about the responsiveness rather than sensitivity of the regulatory system. Maximal stimulation rarely, if ever, occurs under ordinary, everyday life conditions, and these results therefore had minor significance for the...
Of all the hemorrhagic fevers, Marburg, Ebola-Z, and Ebola-S have the highest case-fatality rates, the most severe hemorrhagic manifestations, and the most pronounced liver necrosis. The pathophysiologic changes are still obscure. There is an early and profound leukopenia, followed by a dramatic neutrophilia with a shift to the left, and very little monocyte infiltration in sites of parenchymal necrosis in the liver, but no unequivocal evidence of disseminated intravascular clotting. Antigen is localized in the liver, spleen, kidney, and adrenal glands, where virus particles can also be seen by electron microscopy.
Hormones control a vast array of bodily functions, including sexual reproduction and sexual development, whole-body metabolism, blood glucose levels, plasma calcium concentration, and growth. Hormones are produced in, and released from, diverse places, including the hypothalamus and pituitary, the adrenal gland, the thyroid gland, the testes and ovaries, and the pancreas, and they act on target cells that are often at a considerable physical distance from the site of production. Since they are carried in the bloodstream, hormones are capable of a diffuse whole-body effect, as well as a localized effect, depending on the distance between the production site and the site of action. In many ways the endocrine system is similar to the nervous system, in that it is an intercellular signaling system in which cells communicate via cellular secretions. Hormones are, in a sense, neurotransmitters that are capable of acting on target cells throughout the body, or conversely, neurotransmitters...
Mutation, which means there is a wide possibility that the mutation will find expression not only in intestinal but also in extra-intestinal sites including the thyroid, pancreas and duodenum, adrenal glands and liver. Such variability in clinical manifestation of the same genetic disorder represents real problems for physicians in terms of the right initial diagnosis, therapeutic options, follow-up and need for accurate clinical surveillance of the relatives.
Imaging techniques can help to clarify the etiology of hypercortisolism. These usually include MRI of the pituitary and computed tomography (CT) scanning of the adrenal glands. CT and MRI scans of the chest and abdomen and isotope scans are also employed when searching for ectopic ACTH-secreting tumors. Bilateral enlargement of the adrenal glands with preservation of a relatively normal overall glandular configuration is observed in both CD and ectopic ACTH production (71,72). Approximately 10 to 15 of patients with ACTH-dependent CS demonstrate bilateral adrenocortical nodules (macronodular hyperplasia).
The physical examination reveals only a small proportion of all testicular tumors in CAH, depending on their size. For more accurate detection of these tumors, imaging techniques, such as ultrasound and magnetic resonance imaging (MRI), are required (3,5,6,9,17,18). A comparative study in males with CAH concluded that ultrasound is the method of choice, because it is as sensitive as MRI and more accessible (19). Reports of ultrasound features show a similar picture of hypoechoic lesions adjacent to the mediastinum testis, often lobulated and mostly bilateral (see Fig. 2) (9,18-25). In larger tumors, we have observed hyperechoic reflections (25a). Tumor margins may be blurred on ultrasound but are always well defined on MRI (19,26). On MRI, most of the masses are isointense on T1-weighted images and hypointense on T2-weighted images, as are adrenal glands (19).
Note This test is contraindicated in those with ischemic heart disease, epilepsy, or an unexplained history of loss of conciousness. Hypoadrenalism should be treated before performance of the test with omission of replacement corticosteroid the morning of the test. Prepubertal subjects undergoing testing of GH status should have androgen priming before testing.
Cardiomyopathy with ragged red fibers may be found. The pancreas may display fatty infiltration. The adrenals may be atrophic and small. Glomerular and tubular abnormalities may be found in the kidneys. The lobules of the testes may be atrophic with marked overgrowth of fibrous tissue.
In general, if the patient does not have symptoms of hypoadrenalism, and surgery is planned in the near future, there is no need to routinely evaluate the adrenal axis preoperatively, because evaluation of the adrenal axis is more complicated than the other pituitary axes.
Some words appear in more than one body system to represent different structures. The medulla of the kidney is the inner portion of the organ. Other organs, such as the adrenal gland, ovary, and lymph nodes, may also be divided into a central medulla and outer cortex. But medulla means marrow, and this term is also applied to the bone marrow, to the spinal cord, and to the part of the brain that connects with the spinal cord, the medulla oblongata.
They are versatile organelles, performing different functions in J& Notes different kinds of cells. In an egg cell, for example, they are involved in the production of yolk in an adrenal gland cell, they play a role in making a hormone and in a salivary gland cell, they participate in making a digestive enzyme. Golgi bodies do what they do in accordance with instructions from nuclear DNA. We know that the nuclei of all kinds of cells are alike, and that, in fact, all nuclei come from previously existing nuclei. So it is a striking feature of nuclear DNA that it is able to give certain instructions and leave other instructions switched off. Thus, in differing cells, the instructions may be different by calling upon different DNA segments.
Ascent of the kidneys. Note the change in position between the mesonephric and metanephric systems. The mesonephric system degenerates almost entirely, and only a few remnants persist in close contact with the gonad. In both male and female embryos, the gonads descend from their original level to a much lower position. D. Scanning electron micrograph of a mouse embryo showing the kidneys in the pelvis. B, bladder K, kidney A, adrenal gland G, gonad T, tail. Figure 14.11 A. Unilateral pelvic kidney showing the position of the adrenal gland on the affected side. B and C. Drawing and photomicrograph, respectively, of horseshoe kidneys showing the position of the inferior mesenteric artery. BW, bladder wall U, ureters.
As described in chapter 11, the adrenal gland consists of two parts that function as separate glands. The two parts secrete different hormones and are regulated by different control systems. The adrenal medulla secretes catecholamine hormones epinephrine and lesser amounts of norepinephrine in response to sympathetic nerve stimulation. The adrenal cortex secretes corticosteroid hormones. These are grouped into two functional categories mineralocorti-coids, such as aldosterone, which act on the kidneys to regulate Na+ and K+ balance (chapter 17), and glucocorticoids, such as hydrocortisone (cortisol), which participate in metabolic regulation.
With elevated points Gestational period Three months Life span Up to twelve years in the wild, seventeen in captivity Special anatomy Body is approximately four feet long long, thin legs a tail about half as long as the total body a deep, narrow chest small round skull rounded ears set far back large nasal passages and lungs large heart, adrenals, and arteries spine gives spring for back legs
Since activation of the renin-angiotensin system, along with other neurohormones, occurs during the acute and convalescent phases of MI, this system may play an important role in arrhythmogenesis, which is mediated by direct and in direct effects of angiotensin II (69-71). At least five mechanisms are postulated through which angiotensin II may promote cardiac arrhythmias during MI (i) angiotensin II mediates increases in cardiac filling pressures, thereby abnormally increasing wall stress (72) (ii) angiotensin II directly produces coronary vasoconstriction and decreases coronary blood flow (iii) angiotensin II enhances sympathetic tone and the effects of circulating catecholamines (73) (iv) angiotensin II has direct electrophysiologic effects on cardiac myocytes (74) and (v) angiotensin II stimulates the adrenal glands to produce aldos-terone, promoting renal salt and water retention and potassium excretion leading to potential electrolyte disturbances, such as hypokalemia (75).
Hypoadrenalism may occur during periods of physiologic stress in patients with suppression of the hypothalamic-pituitary-adrenal axis resulting from exogenous steroid administration. During episodes of surgery or major intercurrent illness, it is advisable to provide supplemental steroid therapy to patients who are receiving corticosteroid therapy or who have discontinued such therapy within the previous year. Hydrocortisone (300 mg d or equivalent dosage in three divided doses) may be given IV or IM during the period of maximum stress and subsequently tapered during 5 days. The stress of major nonsurgical illness may be managed with an increase in daily steroid dosage to at least the equivalent of 30 mg of prednisone.
In the adrenals, too, where cholesterol is an important precursor of the steroid hormones, over 80 of the sterol is esterified. By contrast, in brain and other nervous tissues, where cholesterol is an important component of myelin, virtually no cholesterol esters are present.
Any people are more familiar with hormones being produced Notes in animals than in plants. For example, insulin is produced in the pancreas and is involved in the metabolism of sugar. The thyroid gland produces the iodine-containing hormone called thyroxine. The adrenal glands produce adrenalin. With regard to animals, hormones are defined in part as being produced by ductless glands. With regard to plants, hormones are defined as substances produced in minute amounts at one site that have a physiological effect at another site.
The kidneys are located behind the peritoneum in the lumbar region. On the top of each kidney rests an adrenal gland. Each kidney is encased in a capsule of fibrous connective tissue overlaid with fat. An outermost layer of connective tissue supports the kidney and anchors it to the body wall.
Criteria to predict long-term remission are controversial and include undetectable serum cortisol, UFC, and ACTH levels in the (immediate) postoperative period and low-dose dexamethasone suppressibility and deficient responses with CRH and or desmopressin stimulation 7-10 d after surgery (92-96,98,99). However, there are patients with long-term remission who had normal cortisol levels in the immediate postsurgical period (86,100). The lowest risk of relapse has been observed in patients who require prolonged glucocorticoid therapy after adenomectomy (101). A plasma cortisol
The endocrine system involves internal secretions related to the function of the endocrine glands such as the thyroid, adrenal, pituitary. Hormonal secretions from these glands pass directly into the blood stream. An important part of this system, the pituitary, lies at the base of the brain. This master gland secretes a variety of hormones, including hormones that stimulate the thyroid gland and control its secretion of thyroxine, which dictates the rate at which all cells utilize oxygen control the secretion in the adrenal gland of hormones that influence the metabolism of carbohydrates, sodium, and potassium and control the rate at which substances are exchanged between blood and tissue fluid control the secretion in the ovaries of estrogen and progesterone and the creation in the testicles of testosterone control the rate of development of the skeleton and large interior organs through its effect on the metabolism of proteins and carbohydrates and inhibit insulin a lack of insulin...