Biology SAC 2 - Homeostasis (glucose regulation)
What are the hormones involved in the regulation of glucose levels in the blood?
- insulin - glucagon
What is signal transduction?
A series of chemical steps in which an extracellular signalling molecule (e.g. a hormone) affects a change in the intracellular chemical environment and hence a response.
What is negative feedback?
Feedback that tends to stabilize a process by neutralising its rate or output when its effects are too great.
What is meant by the term hypoglycaemic?
Relating to hypoglycemia, an abnormally low level of the sugar glucose in the blood, usually a complication of diabetes, in which the body does not produce enough insulin to fully metabolize glucose.
Be able to write a flowchart including sensors, stimulus, effector and response (including negative feedback)
STIMULUS: Increased level of blood glucose SENSOR: Specialised cells in the Islets of Langerhans EFFECTOR: Beta cells are stimulated to produce insulin RESPONSE: Removal of glucose from the blood NEGATIVE FEEDBACK: The resulting fall in blood glucose level is detected by cells of the pancreas, and negative feedback causes a REDUCTION IN INSULIN PRODUCTION. also causes an increase in glycogen production.
What happens in the body when glucose levels are low?
Glucagon production is increased in response to a fall in blood glucose level. It acts on liver and muscle cells, causing them to break down glycogen and return glucose to the blood.
What is meant by the term hyperglycaemic?
A high blood sugar. An elevated level specifically of the sugar glucose in the blood. Hyperglycemia is often found in diabetes mellitus. It occurs when the body does not have enough insulin or cannot use the insulin it has to turn glucose into energy.
What happens in the body when glucose levels are high?
Insulin production is increased in response to high blood glucose levels. It acts on cells in the liver, muscles and fat tissue. It stimulates them to remove glucose from the blood, to be used immediately or stored as glycogen (a complex carbohydrate). The presence of insulin inhibits the action of glucagon.
What are the glands that produce the hormones that regulate glucose?
Islets of Langerhans in the pancreas. Clusters of endocrine tissue that are responsible for production of insulin and glucagon. Contains two types of endocrine cells: alpha (glucagon) and beta (insulin). Also act as the receptors for blood glucose levels.
How does signal transduction differ depending on the type of hormone?
Target tissues have receptors that are specific to the hormones that will influence its function - must bind to that specific target receptor in the target cells. Some hormones can cause an increase in a cellular function. Others may cause a decrease, or turn the function off.
