Insulin glucagon opposing actions

As discussed in Chapter 5, the body regulates blood glucose concentration through the opposing actions of insulin versus glucagon and epinephrine. 

Opposing actions of insulin and glucagon plus epinephrine. 

The activity of the phosphatases may be controlled by hormones such as insulin, which opposes the action of glucagon (see Chapter 5 IV F). 

When the actions of one hormone oppose the effects of another, the result is antagonism. For example, insulin decreases blood glucose and promotes the formation of fat. Glucagon, on the other hand, increases blood glucose and promotes the degradation of fat. Therefore, the effects of insulin and glucagon are antagonistic. 

Glucagon is a second pancreatic hormone that, like insulin, influences carbohydrate metabolism. However, most of its actions oppose those of insulin. The enkephalins and endorphins are the body s natural painkillers they are thought to be responsible for runner s high. These, among many others, are proteins or are closely related to them. 

Site of synthesis The counterregulatory hormones Glucagon is a polypeptide hormone secreted by the a cells of the pancreatic islets. Glucagon, along with epinephrine, Cortisol, and growth hormone (the "counterregulatory hormones"), opposes many of the actions of insulin. 

Insulin has a range of effects on a number of different metabolic pathways, either stimulatory or inhibitory in many cases glucagon has an opposing effect. It is the insulin to glucagon ratio that is of most importance. Table 2.5 summarises the major effects of insulin the actions of insulin and glucagon are indicated in Figure 2.10. 

Opposing the actions of insulin are the counterregulatory hormones, glucagon, epinephrine, growth hormone, and cortisol. In response to low blood glucose, the coxmterregu-latory hormones increase hepatic glucose... 

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