Chapter 12.5 Flashcards
Which cells are insulin secreted by
-they are secreted by the Beta cells of the pancreatic islets of Langerhans
Which tissues glucose uptake are not affected by insulin
- nervous tissue
- kidney tubules
- intestinal mucosa
- red blood cells(erythrocytes)
- B-cells of the pancreas
How does insulin affect carbohydrates
-it increases carbohydrate metabolism in muscle and fay
How is insulin signalling affected by glucose
- glucose must enter the Beta-cell to be metabolized
- > increasing intracellular ATP concentration
- > increased ATP leads to calcium release in the cell
- > which promotes the exocytosis of preformed insulin from intracellular vesicles
Which cells are glucagon secreted by
- they are secreted by the alpha cells of the pancreatic islets of langerhans
- > primary targets hepatocytes
How does insulin and glucagon relate to ketone synthesis
-insulin limits ketogenesis, while glucagon promotes it
How do amino acids relate to the synthesis of glucagon
- amino acids, especially basic ones promote the secretion of glucagon
- > thus glucagon is also secreted in response to ingestion of a meal rich in proteins
How does cortisol affect the body
- it elevates blood glucose levels, increasing glucose availability for nervous tissues
- > it does this by inhibiting glucose uptake in most tissue
- > increases hepatic output of glucose via gluconeogenesis, particularly from amino acids
What does long term exposure to glucocorticoids result in
- it results in persistent hyperglycemia
- > which stimulates the release of insulin
- > this promotes fat storage rather than lipolysis
What do epinepherine and norepinepherine do to glycogen phosphorylase
- they increase the activity of glycogen phosphorylase
- > promoting glycogenolysis
- > this increases glucose output by the liver
- > increases glycogenolysis in the skeletal muscles
- note that skeletal muscles or muscle tissue in general don’t have glycogen phosphorylase
- > so glycogen cannot be released
What are thyroid hormone levels like
- thyroid hormones are kept more or less constant
- >rather than changes with metabolic state
How does thyroid hormones affect metabolic rate
- it increases basal metabolic rate
- >there is increased oxygen consumption and heat production when they are secreted
Describe how T4 and T3 hormones affect basal metabolic rate
T4
- > there is an increase in metabolic rate produced by T4 after several hours
- > may last for several days
T3
- > produces a more rapid increase in metabolic rate
- > shorter duration of activity
Is T4 a precursor to T3
-yes
What are thyroid hormones effects on lipid and carbohydrate metabolism
-they accelerate cholesterol clearance from the plasma and increase the rate of glucose absorption from the small intestine
