mindarie senior college 3a/3b human biological science homeostasis homeostatic mechanisms
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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
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