Lecture 17

Question 1

What is metabolism?

Answer 1

The sum of all chemical changes and physical changes that occur in body tissue (processes that create and spend ATP)

Question 2

What is a basal metabolic rate?

Answer 2

The estimate of the number of calories the entire body requires to produce enough ATP to maintain all basic functions at rest

Question 3

What is the nutrient pool?

Answer 3

All the organic molecules that can be absorbed by cells and used by mitochondria

Question 4

What is the different between hormonal actions that directly affect the metabolic rate, and hormonal effects that affect metabolism by mobilizing the nutrient pool?

Answer 4

Hormones directly affect metabolic rate by acting on mitochondria, hormones mobilize the nutrient pool by altering the availability of nutrients in the bloodstream

Question 5

What are the key symptoms of hyperthyroidism?

Answer 5

• intolerance to heat
• bulging eyes
• facial flushing
• tachycardia
• increase in systolic BP
• weight loss
• muscle wasting

Question 6

What is diabetes mellitus type 1? How is it treated?

Answer 6

• destruction of beta cells so there is no insulin secretion

- high blood glucose and glucose wasting, and can be treated with insulin injections

Question 7

What are the symptoms of diabetes mellitus type II? How is it treated?

Answer 7

• insulin resistance/insensitivity of insulin receptors

- treatment: insulin, oral medication, diet and exercise, glucose meter

Question 8

How is most of the ATP produced in the body?

Answer 8

Aerobic catabolism in the mitochondria (citric acid cycle)

Question 9

What are two hormones that the thyroid releases?

Answer 9

T3 and T4

Question 10

what are the symptoms of hypothyroidism?

Answer 10

• intolerance to cold
• facial and eyelid Edema
• extreme fatigue
• anorexia
• apathy
• lethargy
• muscle aches
• weight gain

Question 11

What is the half life and potency of t3 and t4?

Answer 11

Half life: T3 is 1 day, T4 is 7 days

Potency: t3 is 3-4 times more potent than t4

Question 12

How do thyroid hormones affect metabolic processes?

Answer 12

• Indirectly By changing gene expression through nuclear receptors
• directly by binding to receptors on mitochondria and changing BMR

Question 13

How does epinephrine and glucagon affect metabolism?

Answer 13

By mobilizing glucose and fatty acids from the liver and adipose tissue

Question 14

How do glucocorticoids and GH affect metabolism?

Answer 14

By mobilizing fatty acids from adipose tissue and promoting lipid uptake and gluconeogenesis

Question 15

What is the glucose sparing effect?

Answer 15

Glucocorticoids and GH promote the use of lipids for metabolism by most cells so that available glucose is saved for the central nervous system

Question 16

How does the pancreas regulate blood glucose/glucose use?

Answer 16

Alpha cells: secrete glucagon (released when glucose levels are too low)
Beta cells: secrete insulin (released when the glucose levels increase)
- glucagon and insulin have opposing negative feedback loops

Question 17

How does insulin cause glucose levels to decrease?

Answer 17

• stimulates uptake by cells

- stimulates glycogenesis in liver

Question 18

How does glucagon cause glucose levels to increase?

Answer 18

causes gluconeogenesis and glycogenolysis in liver to release glucose

Question 19

What are severe, hypoglycemic, Normal, high, and metabolic consequential blood glucose levels?

Answer 19

Severe hypoglycemia: less than 3 mmol/L
Hypoglycemia: less than 3.9 
Normal: less than 7
High: less than 10
Metabolic consequences: 10 to 27.7+

Question 20

What is the benefit of having two different hormones to regulate blood glucose levels? Downside?

Answer 20

• more fine level of control

- both processes take ATP, so requires more energy

Question 21

How do beta cells regulate insulin release of insulin?

Answer 21

• Decrease in glucose entry into beta cell through GLUT, slows metabolism, decrease in ATP, K-ATP channel opens and K leaks out of the cell. The cell stays at resting membrane potential and insulin stays inside the cell
• increase in glucose entry through GLUT, more ATP production, K-ATP channel closes, the cell is depolarized and Ca2+ enters the cell. This triggers exocytosis of insulin vesicles

Question 22

What is a key function of insulin in regulating blood glucose?

Answer 22

Insulin binds to target cell receptors and stimulates the insertion of GLUT into the membrane and allowing glucose uptake

Question 23

How does insulin affect glycogen synthesis in the liver?

Answer 23

Insulin binds to receptor on the liver, and converts glucose to G6P so that the concentration gradient favours glucose entering the cell