Homeostasis Flashcards
What do alpha cells produce
Glucagon
What dk beta cells produce
Insulin
Function of endocrine glands
Secrete to bloodstream
Function of exocrine glands
Produce digestive enzymes
Why is glucose an important molecule for energy
Required for respiration, …..
What controls blood glucose
Insulin and glucagon
What happens when blood glucose is too high
Insulin is secreted, it acts on muscles and liver cells. Glucose is taken up by these cells and conc of glucose in blood falls
What happens when blood glucose is too low
Glucagon is secreted, acts on liver cells, glucose is released from these cells so conc of blood glucose rises
What are the islets of langerhans
Cell clusters that produce hormones like glucagon and insulin
How does insulin work
Binds to receptors on surface of muscle and liver cells
Insulin increases permeability of muscle cells to glucose
Insulin activates series of enzymes that convert glucose to glycogen ( glycogenesis)
Insulin increases the rate of respiration in muscle cells
These actions reduce the conc of glucose in bloodstream
What is glycogenesis
Where insulin activates a series of enzymes on both muscle and liver cells that convert glucose to glycogen
Structure of insulin
Protein based hormone
What is gluconeogenesis
Fats and amino acids combined to form glucose in liver
Function of glucagon
Binds to receptors on surface of liver cells
Generation of glucose from non-carbohydrate substrates
These increase conc of glucose in bloodstream
What is glycogenolysis
Series of enzymes activated that breakdown glycogen into glucose.
What is an example of negative feedback
The control lf blood glucose
What happens if blood glucose is too high
Receptors in pancreas detect increase
B cells begin secreting insulin and a cells stop secreting glucagon
Insulin binds to receptors on liver/muscle cells
Glycogenesis activated & glucose to glycogen so levels fall
What happens if blood glucose levels fall
Receptors detect
B cells stop insulin & A cells start glucagon
Glucagon binds to receptors in liver
Glycogenesis & glucongenesis activated & more glucose produced so levels rise
How does insulin decrease levels of blood glucose
Increase permeability of body cells to glucose by adding glucose carriers
Glycogenesis
Lipogenesis - conversion of glucose into fatty acids
How is glucose transported in cells
Using channel proteins
Give an example of a channel protein
GLUT4 - sound in skeletal and cardiac tissue
At low concs of insulin, GLUT4 is packaged inside vesicles in cytoplasm
When insulin binds to receptors, GLUT4 activated
It fuses with cell membrane
Glucose can then be transported through GLUT4 protein
Cyclic AMP
Secondary messenger, amplifies original signal
