Burned in "Fight or Flight" response

FIGURE 11-11 Possible scenario for the mode of action of epinephrine on the hepatocyte to generate glucose from increased glycogenolysis and gluconeogenesis. Epinephrine is released through the stress pathway by way of a two-neuron system, ending on an acetylcholinergic neuron innervating the adrenal medulla. The acetylcholine binds to membrane receptors on the chromaffin cell, causing an increased cellular uptake of Ca2+. This results in the release of epinephrine (and other components) from granules through exocytosis. The epinephrine released binds to a-receptors on hepatocytes (and on cells that bring about contraction and increased blood pressure), causing an elevation in the cytosolic Ca2+ concentration. This may be brought about by activating the arreceptor-linked Ca2+ channel. Elevated Ca2+ stimulates phosphoryl-ase kinase activity, glycogen synthase I (the effect of Ca2+ may be indirect here), and gluconeogenesis, all of which lead to the generation of glucose and an increase in circulating glucose levels for use in fight-or-flight responses in adapting to the original stress.

is an increase in the number of /3-receptors without a detectable change in the number of a-receptors.

Desensitization is another regulatory aspect of adrenergic receptors. Prolonged exposure to an agonist such as epinephrine leads to decreased responsiveness to a given target tissue. This desensitization occurs with both a- and /3-receptors. The mechanisms of these responses are summarized in Figure 11-14. Certain cells in culture contain adenylate cyclase but lack /3-

adrenergic receptors. The membranes have been isolated from such cells and combined with extracts from other cells containing the receptor. The entire system can be reconstituted in the formerly receptor-deficient membrane. The reconstituted system reproduces the properties of a normal cell membrane in terms of the effects of agonists and antagonists in stimulating adenylate cyclase. Such experiments tend to strengthen our conception of the receptor system.

Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

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