Mindarie Senior College3A/3B HUMAN BIOLOGICAL SCIENCE

HOMEOSTASIS

HOMEOSTATIC MECHANISMS

Glucose Regulation

SPECIAL TERMS

• Insulin – hormone produced by the cells of the islets of the Langerhans (pancreas). Is responsible for the conversion of glucose to glycogen and stored in the liver (glycogenesis). It also increases the absorption and utilisation of glucose by the cells. And so reduces the amount of glucose in the blood.

• Glucagon – produced by the alpha cells of the islets of Langerhans (pancreas). Is responsible for increases in blood levels of glucose. It does this by stimulating the glycogen to convert to glucose (glycogenolysis) and by converting proteins and lipids to glucose (gluconeogenesis).

I

Islet of Langerhan

Blood vessels

• Other hormones involved in glucose regulation.– Adrenalin regulates carbohydrate metabolism

and increases glucoses levels in blood.– Growth hormone increases fat usage and

decrease the use of glucose.– Thyroxine increase glucose absorption from

intestine.– Cortisol converts amino acids to glucose.

RECEPTOR The pancreas

detects changes low glucose a

cells high glucose b

cells

MODULATOR a cells increase glucagon b cells reduce insulin

EFFECTOR Cells in the body

absorb less glucose,

gluconeogeneis or glycogenolysis

RESPONSE Glucose is not removed from the blood but released into blood

STIMULUS Blood glucose

falls Blood glucose

rises

MODULATOR a cells decrease

glucagon b cells increase

insulin

EFFECTOR Cells in the body

absorb glucose, and glycogenesis

RESPONSE Glucose is removed from the

blood stream

CONSOLIDATION

• Newton and Joyce• Page 149• Review Questions 1 to 5• Page 150• Apply Your Knowledge, Questions 1 and 2