Endocrine Pancreas and Adrenals Flashcards
Which 4 cells make up the Islets of Langerhans, percentages and excretion?
1) B Cells: Insulin (70%)
2) A Cells: Glucagon (20%)
3) D Cells: Somatostatin (8%)
4) PP Cells: Polypeptide (2%)
What significance is location of alpha and beta cells next to each other in IOL?
Able to “cross talk” –> Reciprocal action in response
What 3 functions does insulin have?
1) Supress lipolysis and muscle breakdown
2) Glycogenesis: Supress hepatic glucose output
2) Increase glucose uptake into muscles and fat cells
What 4 functions of glucagon?
1) Glycogenolysis
2) Gluconeogenesis: Synthesise new glucose from excess fats and AA
3) Stimulate lipolysis and muscle breakdown
4) Reduce peripheral glucose uptake
(Stimulate release of gluconeogenic precursors)
What is the biphasic process of insulin release?
1) Phase 1: Stored insulin rapidly released
2) Phase 2: Slower release of newly synthesised insulin
What is the mechanism of insulin secretion from beta cells?
1) Glucose binds to beta cells –> G-6-P
2) ADP converted to ATP as K+ channels close
3) Membrane depolarises as Ca2+ open with Ca2+ influx
4) Insulin released
What signifies high insulin due to endogenous production?
C Peptide
What glucose transporter allows glucose uptake into fat and muscle cells?
GLUT-4
What happens in insulin action against fat and muscle cells?
1) Insulin binds to membrane receptors
2) Intracellular cascade is stimulated
3) GLUT-4 mobilisation to plasma membrane occurs
4) GLUT-4 integrates into plasma membrane and glucose can enter through GLUT-4
What is a normal blood glucose range?
4-6mmol/mol
What are the long and short term response to high blood glucose?
1) Short Term: Glycogenesis
2) Triglyceride prod - lipogenesis
What are the short and long term responses to low blood glucose?
Short: Glycogenolysis
Long: Gluconeogenesis
What are 3 places where glucose sensors are found?
1) Pancreatic islets
2) Medulla
3) Hypothalamus
What changes happen to glucose and insulin following a meal?
1) Insulin release is increased
2) Glucose returned to liver and muscles to replenish glycogen stores
3) Excess glucose converted into fat
What does the adrenal cortex produce?
Steroid Hormones
What does the adrenal medulla produce?
Adrenaline and noradrenaline (Catecholamines)
What are the 3 layers of adrenal cortex?
1) Zona Glomerulosa
2) Zona Fasciculata
3) Zona Reticularis
What does each layer of adrenal cortex produce?
1) ZG: Mineralocorticoids e.g. Aldosterone
2) ZF: Glucocorticoids e.g. Cortisol
3) ZR: Androgens: DHEA
What are steroid hormones synthesised from?
Cholesterol (Lipids)
What do steroid hormones bind to as transported through blood?
CBG proteins - Water insoluble so need to bind to be transported
