Insulin and Glucagon: Regulation of Blood Glucose Levels, Summaries of Nursing

Download Insulin and Glucagon: Regulation of Blood Glucose Levels and more Summaries Nursing in PDF only on Docsity!

PHYSIOLOGICAL PROCESS

K e y P o i n t s

ENDOCRINE PANCREAS

Clusters of endocrine cells are organized into pancreatic islets which secrete hormones.

INSULIN

• water-soluble, protein hormone
• synthesized and stored in granules in beta cells until needed
• targets muscle , liver and adipose cells proinsulin (inactive) is split into insulin (active) and C peptide Both are stored in granules and released when beta cells are stimulated.

occurs in 15 minute cycles , even when fasting (= basal release)

INSULIN SECRETION

primarily stimulated by elevated blood glucose levels (= stimulated release)

𝛃 CELL sympathetic stimulation (epi, NE) elevated levels of some amino acids digestive hormones (GIP, GLP-1) HIGH BLOOD GLUCOSE (> 4 mM) parasympathetic stimulation via vagus nerve (Ach)

+^ + INSULIN Factors regulating insulin release…

EFFECTS OF INSULIN

① (^) nutrient uptake ② (^) metabolic effects ③ protein synthesis

The overall effects of insulin:

1. promote the uptake of nutrients into cells
2. promote nutrient use or storage by cells
3. prevent the breakdown of fuel that has already been stored

In muscle and adipose tissue cells à insulin stimulates the movement of GLUT- 4 transporters from vesicles inside the cell to the plasma membrane. Glucose uptake

Insulin stimulates lipoprotein lipase to release fatty acids and monoglycerides from lipoproteins for uptake into adipose tissue. Lipid uptake

amino acids blood glucose triglycerides glycogen proteins glucose glycogen glucose What happens to glucose that enters adipose tissue? fatty acids ATP blood lipids triglycerides Glucose in excess of glycogen stores is converted to TGs for storage in liver cells.

Insulin stimulates the conversion of glucose to glycerol or fatty acids for TG synthesis in adipose tissue. glucose glycerol GLUT- 4 fatty acids blood lipids + triglycerides In other words, glucose is stored as fat in adipose tissue. ATP glycolysis

• glucose transporters
• insulin receptors
• metabolic enzymes

G L U C A G O N