WEEK 10 - Topic 5 - Homeostasis (Blood Glucose & Insulin)

Question 1

What is glucose?

Answer 1

Glucose is a monosaccharide, the most basic unit of carbohydrates and is the primary source of energy for cells.

• Simplest form of sugar

Question 2

The brain requires what for energy? Does it require proteins or fats?

Answer 2

Glucose

No.

Question 3

What can low blood glucose levels lead to?

Answer 3

• Decrease in CNS activity
• Coma and/or death
• (Less acutely) Many other cell types in the body also starve

Question 4

What produces insulin?

Answer 4

Beta cells of the pancreas

Question 5

What are the primary roles of insulin?

Answer 5

Its main effect is to lower blood glucose levels

• Insulin “sweeps” glucose out of the blood, causing it to be used for energy, or converted to other forms (glycogen or fats)
• Insulin acts on insulin receptors to promote facilitated diffusion of glucose into tissue cells

Question 6

What are the other minor roles of insulin?

Answer 6

• Reduces production of glucose from glycogen, amino acids or fats
• Insulin is the major anabolic hormone, regulating protein and fat metabolism

Question 7

What factors stimulate pancreatic beta cells to secrete insulin?

Answer 7

• Elevated blood glucose levels

- Rising blood levels of amino acids and fatty acids

Question 8

Outline the role of insulin in blood glucose homeostasis

Answer 8

1. Stimulus: rise in blood glucose levels
2. Pancreas detects rise in blood glucose levels and secretes insulin
3. a) Insulin stimulates glucose uptake by cells
4. b) Insulin stimulates glycogen formation and inhibits glycogen breakdown.
5. Blood glucose levels fall to normal range

Question 9

Is insulin needed for glucose entry into livers, kidneys and the brain?

Answer 9

No. They have easy access to blood glucose.