Insulin, Glucagon, & Leptin Flashcards
True or False: The pancreas is an organ that does not control blood sugar.
FALSE - Pancreas is an organ that controls blood sugar.
What are the characteristics of alpha cells?
- 20% of cells in islet
- glucagon
What are the characteristics of beta cells?
- 65% of cells in islet
- insulin
What are the characteristics of gamma cells?
- Rare
- Pancreatic polypeptide
What are the characteristics of delta cells?
- 10% of cells in islet
- somatostatin
Describe the regulation of blood sugar when it is high.
After you eat a meal, your blood sugar rises quickly. This promotes insulin release to the pancreas. Then, insulin stimulates glucose uptake from the blood, stimulates glycogen formation, and goes to the liver, lowering blood sugar.
Describe the regulation of blood sugar when it is low.
When blood sugar is low, it promotes glucagon release to the pancreas. This then leads to glucagon stimulating glycogen breakdown in the liver. This results in raising your blood sugar.
Describe the mechanism of insulin secretion.
High blood glucose leads to an increased ATP/ADP ratio, which then leads to the ATP-sensitive K+ channel to close. Then this causes membrane depolarization, then Ca2+ enter, which leads to insulin secretion.
What kind of hormone is glucagon?
Peptide hormone
Are the actions of glucagon opposite of insulin?
Yes
How is the control of glucagon secretion induced?
Induced by decreased food intake and decreased blood glucose.
Are actions of glucagon catabolic or anabolic?
Catabolic
What are the actions of glucagon?
- Mobilizing glucose by increasing glycogenolysis and gluconeogenesis
- Mobilizing fatty acids by increasing lipolysis
- Increasing amino acid catabolism
What kind of hormone is leptin?
Peptide hormone
Where does leptin’s production occur?
Adipose tissue
What are leptin’s target organs?
Hypothalamus
What is the receptor for leptin?
Leptin receptor
What are the effects of leptin?
- suppresses appetite
- promotes energy expenditure
- decreases lipogenesis and increases lipolysis
Describe the regulation of leptin when there is an increase in fat?
When there is an increase in fat, leptin goes to the leptin receptor (which is in the hypothalamus). This leads to a decrease in food intake and an increase in thermogenesis, which overall decreases fat.
Insulin and glucagon work together to maintain ________ balance.
Energy
What are the specific actions insulin does to the liver?
What are the specific actions glucagon does to the liver?
Insulin:
- promotes glucose absorption
- promotes glycogenesis
Glucagon:
- promotes glycogenolysis (breakdown of glycogen)
- promotes gluconeogenesis
What are the specific actions insulin does to the muscle?
What are the specific actions glucagon does to the muscle?
Insulin:
- promotes amino acid absorption
- promotes glucose absorption
- promotes synthesis
Glucagon:
- promotes protein degradation
- promotes amino acid catabolism
What are the specific actions insulin does to adipose?
What are the specific actions glucagon does to adipose?
Insulin:
- promotes lipogenesis
Glucagon:
- promotes lipolysis
