Homeostasis Of Blood Sugar Flashcards
Describe the feedback loop for a person who has just eaten a carbohydrate rich meal in terms of their blood sugar levels.
Stimulus - high blood sugar
Receptor - beta cells in islets of langerhans
Modulator - islets of langerhans and beta cells
Effector - liver and skeletal cells
Response - reduction in blood sugar via glycogenesis. Lipogenesis and increasing transport of glucose in cells.
Soon after a meal rich in carbs, the concentration of glucose in the blood leading to and from the lover was measured. What would be expected to happen?
Glucose content of blood entering liver would be much greater than normal while that leaving the liver would be slightly higher than normal.
Describe the feedback loop for a person who has just exercised in terms of their blood sugar levels.
Stimulus - low blood sugar
Receptor - alpha cells in islets of langerhans. And adrenal medulla and cortex.
Modulator - alpha cells secrete glucagon. Adrenal medulla secretes adrenaline and adrenal cortex secretes cortisol.
Effector - liver and skeletal cells. Body cells.
Response - increase in blood glucose via glycogenolysis, glucogeonesis and lypolysis.
What are the blood sugar levels?
Amount of glucose in the blood.
Which glands affect the levels of glucose in the blood?
The pancreas and adrenal glands.
What is the normal level of glucose in the blood?
4-6 millmoles per litre.
What is the role of the pancreas in terms of blood sugar?
Within pancreas are hormone secreting cells called Islets of Langerhans.
Alpha cells: secrete glucagon - increase blood sugar by stimulating glycogenolysis.
Beta cells: secrete insulin - decrease blood sugar
What is the role of the adrenal glands in terms of blood sugar?
Produce many hormones.
Glucocorticoids: from adrenal cortex.
Nor/adrenaline: from adrenal medulla.
Stimulated by ACTH.
What is the main hormone secreted from the adrenal glands?
Cortisol: regulates carbohydrate metabolism by making sure enough energy is provided to cells, which stimulates conversion of glycogen to glucose.
What is the role of the liver in terms of blood sugar?
Able to convert glucose into glycogen for storage or glycogen to glucose for release into blood.
Glycogeneis and glycogenolysis occur in the liver, what do these processes do?
Glycogenesis: glucose chemically combined to form glycogen - insulin.
Glycogenolysis: converting glycogen to glucose.
When blood sugar levels are too high, insulin is released from the pancreas, what does this do?
Stimulates glycogen formation in the liver.
How does insulin maintain blood glucose at homeostatic levels?
Increases the formation of glycogen.
Describe 3 cellular effects of insulin in response to an increased blood concentration of glucose.
Promotes uptake of glucose by cell.
Converts glucose to glycogen - glycogenesis.
Can cause formation of glycogen to glucose in skeletal muscles.
