Adrenal glands medulla

Tennekes, H., Gembardt, C., Dammann, M., and van Ravenzwaay, B. (2004a). The stability of historical control data for common neoplasms in laboratory rats Adrenal gland (medulla), mammary gland, liver, endocrine pancreas, and pituitary gland. Regul Toxicol Pharmacol 40, 18—27. 

Pituitary Adenylyl Cyclase-activating Polypeptide (PACAP) is a 38-amino acid peptide (PACAP-38), which is widely expressed in the central nervous system. PACAP is most abundant in the hypothalamus. It is also found in the gastrointestinal tract, the adrenal gland and in testis. Its central nervous system functions are ill-defined. In the periphery, PACAP has been shown to stimulate catecholamine secretion from the adrenal medulla and to regulate secretion from the pancreas. Three G-protein coupled receptors have been shown to respond to PACAP, PAQ (PACAP type I) specifically binds PACAP, VPACi and VPAC2 also bind vasoactive intestinal peptide (VDP). Activation of PACAP receptors results in a Gs-mediated activation of adenylyl cyclase. 

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 adrenal gland is located on the upper segment of the kidney (Fig. 42-1). It consists of an outer cortex and an inner medulla. The adrenal medulla secretes the catecholamines epinephrine (also called adrenaline) and norepineprhine (also called noradrenaline), which are involved in regulation of the sympathetic nervous system. The adrenal cortex consists of three histologically distinct zones zona glomerulosa, zona fasciculata, and an innermost layer called the zona reticularis. Each zone is responsible for production of different hormones (Fig. 42-2). 

Adrenal medulla. Derived from neural crest tissue, the adrenal medulla forms the inner portion of the adrenal gland. It is the site of production of the catecholamines, epinephrine and norepinephrine, which serve as a circulating counterpart to the sympathetic neurotransmitter, norepinephrine, released directly from sympathetic neurons to the tissues. As such, the adrenal medulla and its hormonal products play an important role in the activity of the sympathetic nervous system. This is fully discussed in Chapter 9, which deals with the autonomic nervous system. 

Adrenal gland A triangle-shaped organ positioned at the top of the kidney which functions as a double endocrine gland . The larger outer adrenal cortex secretes three classes of steroid hormones glucocorticoids (e.g., cortisol), minerlocorticoids (aldosterone) and small amounts of sex steroids (e.g., testosterone). The inner adrenal medulla secretes catecholamines (e.g., adrenaline and noradrenaline). 

As discussed in previous chapters, secretion of adrenocortical steroids is controlled by the pituitary release of corticotrophin (ACTH). The adrenal gland has two main parts, adrenal medulla, which is responsible for the release of catecholamines and adrenal cortex which secretes glucocorticoids. 

Adrenal Conical Hormones. The adrenal gland is made up of two parts, the medulla and the cortex, each of which secretes characteristic hormones. The hormones of the adrenal medulla art- the catecholamines, epinephrine adrenalin and norepinephrine (noradrenalint. which are closely related chemically, dil lning only in that epinephrine has an added methyl group. See Table I. In fact, animal experiments have established a metabolic pathway lor Ihe biosynthesis of both compounds Irom Ihe ammo acid pheny lal.inine. which involves enzy malic oxidation and decarboxylation reactions It is also to he noted ihui the isomeric form of norepinephrine is most important the natural D-lonn (which incidentally, is levorntatory) has many times die uciiviiy of die synthetic isomer. Epinephrine has a pronounced action upon the circulatory system, increasing both blood... 

Adrenal glands are located at the superior poles of each kidney. Each adrenal gland is composed of an outer cortex and an inner medulla. The hormones associated with the adrenal cortex and adrenal medulla are described in the following sections. 

In rabbits given a single intravenous dose of aluminum lactate, aluminum concentrations did not increase above controls in the cerebellum, white brain tissue, hippocampus, spinal cord, adrenal glands, bone, heart, testes, or thyroid (Yokel and McNamara 1989). Treated animals did have significant increases of aluminum in the liver, serum, bile, kidneys, lungs, and spleen. The liver of exposed rabbits had over 80% of the total body burden of aluminum. Persistence of aluminum in the various tissues, organs, and fluids varied. Estimated half-times of aluminum were 113, 74, 44, 42, 4.2, and 2.3 days in the spleen, liver, lungs, serum, renal cortex, and renal medulla, respectively. The kidneys of treated rabbits also demonstrated a second half-time which exceeded 100 days. 

The adrenal glands are located anatomically above the kidneys. They comprise a three-layer cortex and a medulla. The medulla is the source of catecholamines such as epinephrine, the fight-or-flight hormone. The cortex is the source of aldosterone, the primary mineralocorticoid that is involved in the regulation of sodium reabsorption in the kidneys. In addition, the cortex is also the source of steroids known as glucocorticoids, of which cortisol is the principal endogenous representative. Synthesis and release of cortisol is under the control of adrenocorticotropic hormone (ACTH). 

Adrenal medulla the inner layer of the adrenal gland which is involved in the production of dopamine, adrenaline and noradrenaline. 

The adrenal gland appears to be one organ, but functionally it is two different organs. The inner core of the gland is the adrenal medulla. It is imder nervous control and secretes epinephrine (adrenaline) and norepinephrine (noradrenaline). The outer layer of the adrenal gland is the adrenal cortex. The cells of the adrenal cortex closest to the surface of the gland constitute the zona glomerulosa. These cells synthesize aldosterone and release it into the bloodstream. 

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