• glucose is required for cell respiration

• glucose must be present in the blood at all times

• the levels have to be kept within certain limits to prevent damage to the body

• too high or low you may die

control of blood glucose

• 2 hormones control glucose levels

• insulin and glucagon

• these are released from the islets of Langerhans

• alpha cells release glucagon

• beta cells release insulin

rise in glucose levels

• absorption of carbohydrates such as starch and sugars after a meal

• starch is broken down into glucose before absorption

• glucose is absorbed by the small intestine

• blood glucose levels will rose

response to rise in glucose levels

• conversion of amino acids to glycerol and glucose.excess amino acids absorbed from food cannot be stored,they are deaminated in the liver

• the amino part is converted into urea and excreted.the rest of the molecule is converted into glucose

• conversion of glycogen into glucose

effects of insulin

• released when glucose levels rise

• target cells are liver and muscle

• cause these cells to take up glucose by increasing their membrane permeability by adding more transport proteins to the membrane

• glucose uptake is by facilitated diffusion

• stimulate the cells to produce an enzyme that converts soluble glucose into insoluble glycogen

• the glycogen will act as a glucose store

• as a result blood glucose levels fall

• they are stored as glycogen rather than glucose so that the balance of the cell is not disturbed

effects of insulin

• increases the rate of respiration to lower glucose levels

• increases the rate of conversion of glucose into fat in adipose cells

⭐ blood glucose rises → detected by beta cells → beta cells release insulin → blood glucose levels fall to normal → detected by beta cells → reduce insulin production.

effects of glucagon

• released when glucose levels fall

• target cells are liver cells

• cause cells to produce an enzyme that converts glycogen to glucose

• gluconeogenesis

• causes the cells to release the glucose into blood

• glucose levels in the blood will rise - bringing it back to normal

⭐ blood glucose levels fall → detected by the alpha cells → alpha cells release glucagon → blood glucose levels fall to normal → detected by alpha cells → reduce glucagon production