Question

1. Briefly describe the impact of exercise on circulating levels of insulin, glucagon, and epinephrine.

Answer 1

Exercise raises glucagon levels. Glucagon reduces insulin.

insulin concentration decreases during exercise of increasing intensity. This is important because if exercise was associated with an increase in insulin, the plasma glucose would be taken up into all tissues (including adipose tissue) at a faster rate, leading to an immediate hypoglycemia. Adipose tissue fatty acid release would also be lower and fatty acids couldn't be used as a fuel. Lower concentration of insulin during exercise favors the mobilisation of glucose from the liver and makes blood glucose homeostasis possible.

Glucagon plays an active role in allowing the body to regulate the utilisation of glucose and fats.

Glucagon is released in response to low blood glucose levels and to events whereby the body needs additional glucose, such as in response to vigorous exercise.

When glucagon is released it can perform the following tasks:

• Stimulating the liver to break down glycogen to be released into the blood as glucose
• Activating gluconeogenesis, the conversion of amino acids into glucose
• Breaking down stored fat

• Glucagon serves to keep blood glucose levels high enough for the body to function well.

  When blood glucose levels are low, glucagon is released and signals the liver to release glucose into the blood.

Epinephrine level rises during exercises. Epinephrine, often referred to as adrenaline because it is produced by the adrenal gland, elevates cardiac output, increases blood sugar (to help fuel exercise), promotes the breakdown of glycogen for energy and supports fat metabolism.