control of blood glucose and diabetes

what is the function of insulin

to lowers the blood glucose when it is too high

what is the function of glucagon

to raise blood glucose

define Glycogenesis

making glycogen from glucose removed from the blood.

define Glycogenolysis

breaking down stored glycogen into glucose, which can be released into the blood.

define Gluconeogenesis

synthesis of glucose from other molecules such as amino acids.

describe what happens when blood glucose is too high

The rise in glucose concentration is detected by beta cells that are found in the islets of

Langerhans in the pancreas

Insulin is secreted by beta cells, inhibiting alpha cells

Insulin travels in the blood to hepatocytes

insulin binds to the receptors on the membrane of these cells

This increases the permeability of the cells to glucose

increasing the rate of glucose uptake into the cell

describe what happens when blood glucose is too low

Alpha cells in the islets of Langerhans in the pancreas detect a fall in blood glucose and

secrete the hormone glucagon

Glucagon secretion inhibits beta cell action

Glucagon binds to and stimulates hepatocytes to convert glycogen into glucose(glycogenolysis)

Glucose diffuses out of hepatocytes into the blood

describe the second messenger process

Adrenaline binds to a receptor on the cell surface membrane of hepatocytes

causes the receptor to change shape on the inside the membrane.

the enzyme activates the enzyme adenylate cyclase which converts ATP to cyclic AMP

The cyclic AMP then changes shape and activates protein kinase which catalyses the

conversion of glycogen into glucose

describe type 1 diabetes

insulin dependent

occurs early in life

the immune system destroys beta cells in the pancreas

people with type 1 diabetes have to control their blood sugar level by self injecting

insulin

describe type 2 diabetes

often appears later on in life

caused by decreased insulin production or by glycoprotein receptors on target cells

becoming unresponsive to insulin

This is often caused by obesity and diet

This can be controlled by diet manipulation and exercise