Lecture 17 Flashcards
What is metabolism?
The sum of all chemical changes and physical changes that occur in body tissue (processes that create and spend ATP)
What is a basal metabolic rate?
The estimate of the number of calories the entire body requires to produce enough ATP to maintain all basic functions at rest
What is the nutrient pool?
All the organic molecules that can be absorbed by cells and used by mitochondria
What is the different between hormonal actions that directly affect the metabolic rate, and hormonal effects that affect metabolism by mobilizing the nutrient pool?
Hormones directly affect metabolic rate by acting on mitochondria, hormones mobilize the nutrient pool by altering the availability of nutrients in the bloodstream
What are the key symptoms of hyperthyroidism?
- intolerance to heat
- bulging eyes
- facial flushing
- tachycardia
- increase in systolic BP
- weight loss
- muscle wasting
What is diabetes mellitus type 1? How is it treated?
- destruction of beta cells so there is no insulin secretion
- high blood glucose and glucose wasting, and can be treated with insulin injections
What are the symptoms of diabetes mellitus type II? How is it treated?
- insulin resistance/insensitivity of insulin receptors
- treatment: insulin, oral medication, diet and exercise, glucose meter
How is most of the ATP produced in the body?
Aerobic catabolism in the mitochondria (citric acid cycle)
What are two hormones that the thyroid releases?
T3 and T4
what are the symptoms of hypothyroidism?
- intolerance to cold
- facial and eyelid Edema
- extreme fatigue
- anorexia
- apathy
- lethargy
- muscle aches
- weight gain
What is the half life and potency of t3 and t4?
Half life: T3 is 1 day, T4 is 7 days
Potency: t3 is 3-4 times more potent than t4
How do thyroid hormones affect metabolic processes?
- Indirectly By changing gene expression through nuclear receptors
- directly by binding to receptors on mitochondria and changing BMR
How does epinephrine and glucagon affect metabolism?
By mobilizing glucose and fatty acids from the liver and adipose tissue
How do glucocorticoids and GH affect metabolism?
By mobilizing fatty acids from adipose tissue and promoting lipid uptake and gluconeogenesis
What is the glucose sparing effect?
Glucocorticoids and GH promote the use of lipids for metabolism by most cells so that available glucose is saved for the central nervous system
How does the pancreas regulate blood glucose/glucose use?
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
How does insulin cause glucose levels to decrease?
- stimulates uptake by cells
- stimulates glycogenesis in liver
How does glucagon cause glucose levels to increase?
causes gluconeogenesis and glycogenolysis in liver to release glucose
What are severe, hypoglycemic, Normal, high, and metabolic consequential blood glucose levels?
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+
What is the benefit of having two different hormones to regulate blood glucose levels? Downside?
- more fine level of control
- both processes take ATP, so requires more energy
How do beta cells regulate insulin release of insulin?
- 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
What is a key function of insulin in regulating blood glucose?
Insulin binds to target cell receptors and stimulates the insertion of GLUT into the membrane and allowing glucose uptake
How does insulin affect glycogen synthesis in the liver?
Insulin binds to receptor on the liver, and converts glucose to G6P so that the concentration gradient favours glucose entering the cell
