Insulin adrenaline

Table 11.1 Some metabolic effects of insulin. These effects are generally countered by other hormones (glucagon and, in some cases, adrenaline). Hence, the overall effect noted often reflects the relative rates of these hormones present in the plasma...

Biosynthesis and degradation of glycosaminoglycans biosynthesis of collagen, mineralization and demineralization of bone. Fatty acid synthesis and triglyceride storage in adipocytes promoted by insulin and triglyceride hydrolysis and fatty acid release stimulated by glucagon and adrenaline (epinephrine). 

Hormones are intercellular messengers. They are typically (1) steroids (e.g., estrogens, androgens, and mineral corticoids, which control the level of water and salts excreted by the kidney), (2) polypeptides (e.g., insulin and endorphins), and (3) amino acid derivatives (e.g., epinephrine, or adrenaline, and norepinephrine, or noradrenaline). Hormones maintain homeostasis—the balance of biological activities in the body for example, insulin controls the blood glucose level, epinephrine and norepinephrine mediate the response to the external environment, and growth hormone promotes normal healthy growth and development. 

An excess of insulin can cause hypoglycaemia and the hormones that respond to this condition to restore normal glucose levels are known as the counter-regulatory hormones. They are adrenaline, glucagon, growth hormone and cortisol. An increase in the blood levels of these hormones can sometimes be used to conhrm a diagnosis of hypoglycaemia. 

Adrenaline Noradrenaline (+) Growth hormone Glucagon Insulin ... 

The effector systems result in changes in messenger systems that then cause the effects of the hormone. Not surprisingly, the effects of the hormone depend on which hormone is being considered. To illustrate this four hormones - insulin, cortisol, adrenaline and glucagon - are discussed. 

In the ebb phase, there is increased activity of the sympathetic nervous system and increased plasma levels of adrenaline and glucocorticoids but a decreased level of insulin. This results in mobilisation of glycogen in the liver and triacylglycerol in adipose tissue, so that the levels of two major fuels in the blood, glucose and long-chain fatty acids, are increased. This is, effectively, the stress response to trauma. These changes continue and are extended into the flow phase as the immune cells are activated and secrete the proinflammatory cytokines that further stimulate the mobilisation of fuel stores (Table 18.2). Thus the sequence is trauma increased endocrine hormone levels increased immune response increased levels of cytokines metabolic responses. 

Cortical hormones include glucocorticoids (cortisol/corticosterone) and mineralocorticoids (aldosterone) medullar hormones are adrenaline and noradrenaline Pancreas Regulates glucose in blood via production of the hormones glucagon and insulin... 

The non-irritant substances can be injected by this route. The rate of absorption of drug is constant and slow to provide a sustained effect. The site of injection is usually the outer surface of the arm, or front of the thigh. Self medication (e.g. insulin) is possible because deep penetration is not needed. Other drugs which are administered subcutaneously are adrenaline, morphine and certain hormonal preparations. 

Alpha blockers also produce certain metabolic effects such as inhibitory action of adrenaline on insulin secretion is blocked and adrenaline induced rise in blood potassium level is also blocked. 

Every hormone must have one or more receptors, most of which are proteins. These may be found embedded in the outer surface of the plasma membrane, in the cytoplasm, or in the cell nucleus. Binding of a hormone to its receptor often elicits both a rapid response and a slower one. For example, we have seen that glucagon, adrenaline, and vasopressin bind to cell surface receptors and promote the synthesis of cyclic AMP (Fig. 11-4). Tire cAMP induces rapid chemical modifications of many proteins. Some of these may diffuse into the nucleus and affect transcription of genes, a slower response. Insulin (Chapter 11, Section G) also exerts both rapid and slower responses. 

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