Med Consequences Set 3

Front 1

1. What is insulin?

Back 1

- Main hormone controlling intermediary metabolism
- lowers blood glucose
- This coupled with reduced insulin resistance --> diabetes mellitus
- acts on liver, muscle, fat
- overall effect: conserve fuel by facilitating the uptake and storage of glucose, amino acids, and fats after a meal.

Front 2

2. Where is insulin secreted from?

Back 2

The pancreas, the B-cells in the islets of Langerhans

Front 3

3. Which factors regulate or influence the secretion of insulin?

Back 3

- blood glucose concentration
- gastrointestinal hormones secrete insulin (gastrin, secretin, GIP, GLP, GLP1, cholecystokinin)
- other stimuli that release insulin: amino acids (esp. leucine and arginine), fatty acids, parasympathetic nervous system, drugs that act on sulfonylurea receptors
- inhibited by the sympathetic nervous system
- adrenaline increases blood glucose by inhibiting insulin secretion and other ways
- other inhibitors are several peptides like somatostatin, galanin, amylin

Front 4

4. What are the effects of insulin on carbohydrate metabolism?

Back 4

- In liver, insulin inhibits glycogen breakdown and synthesis of glucose from non-carb sources.
- While stimulating glycogen synthesis
- overall effect is to increase hepatic glycogen stores
- in muscle, slow uptake of glucose is the rate limiting step for carb metabolism
- thus, insulin increases facilitated uptake of glucose by the transporter Glut-4 (And in adipose tissue)
- insulin also stimulates glycogen synthesis and glycolysis

Front 5

5. What are the effects of insulin on fat metabolism?

Back 5

- Insulin increases fatty acids and trigylceride synthesis in: adipose tissue and the liver, while simultaneously inhibiting lipolysis
- also inhibits adrenaline's, glucagon's and growth hormone's lipolytic actions on adenylate cyclase

Front 6

6. What are the effects of insulin on protein metabolism?

Back 6

stimulates uptake of amino acids into muscle
increases protein synthesis
while decreasing protein catabolism and oxidation of amino acids in the liver

Front 7

7. Are there any additional effects of insulin?

Back 7

other metabolic effects of insulin:
transporting K+, Ca2+, nucleosides, inorganic phosphates into the cells
insulin has a rapid effects on metabolism, exerted via an altered activity of enzymes and transported proteins
also has longer term actions via altered enzyme synthesis
- cell proliferation in somatic and visceral growth

Front 8

8. Is insulin a catabolic or anabolic hormone?

Back 8

Anabolic