【多选题】How do the hormones maintain the blood glucose levels constant?
A.
The minute-by-minute adjustments that keep the blood glucose level near 4.5 mM involve the combined actions of insulin, glucagon, epinephrine, and cortisol on metabolic processes in many body tissues, but especially in liver, muscle, and adipose tissue.
B.
Insulin signals these tissues that blood glucose is higher than necessary; as a result, cells take up excess glucose from the blood and convert it to glycogen and triacylglycerols for storage.
C.
Glucagon signals that blood glucose is too low, and tissues respond by producing glucose through glycogen breakdown and (in the liver) gluconeogenesis and by oxidizing fats to reduce the need for glucose.
D.
Epinephrine is released into the blood to prepare the muscles, lungs, and heart for a burst of activity. Cortisol mediates the body’s response to longer-term stresses.
【简答题】A.Fast music promotes the sale of hamburgers. B.Background music is played in prisons to make prisoner educated. C.Background music is sometimes very boring to the workers. D.Background music is usual...
【多选题】How does blood glucose regulate insulin secretion by pancreatic β cells?
A.
When blood glucose rises, GLUT2 transporters carry glucose into the β cells, where it is immediately converted to glucose 6-phosphate by glucokinase and enters glycolysis.
B.
With the higher rate of glucose catabolism, 2 [ATP] increases, causing the closing of ATP-gated K + channels in the plasma membrane. Reduced efflux of K + depolarizes the membrane. Membrane depolarization opens voltage-gated Ca 2+ channels, and the resulting increase in cytosolic [Ca 2+ ] triggers the release of insulin by exocytosis.
C.
The brain integrates inputs on energy supply and demand, and signals from the parasympathetic and sympathetic nervous systems also affect (stimulate and inhibit, respectively) insulin release.
D.
A simple feedback loop limits hormone release: insulin lowers blood glucose by stimulating glucose uptake by the tissues; the reduced blood glucose is detected by the β cell as a diminished flux through the glucokinase reaction; this slows or stops the release of insulin. This feedback regulation holds blood glucose concentration nearly constant despite large fluctuations in dietary intake.