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Fuel Homeostasis 3
Duke PA physiology
Question | Answer |
---|---|
What do glycogenolysis, gluconeogenesis and ketone synthesis cause? | increased plasma glucose, increased plasma ketones |
What is the primary target of glucagon? | liver |
What is the glucagon receptor? | G protein linked receptor |
What induces hypoglycemia? | long-lasting workout session (250 minutes) |
What is the first fuel used in exercise? | glycogen |
What is the second fuel used in exercise? | fat, the preferable fuel |
What metabolism occurs when the body is burning fat? | catabolic |
What do insulin levels do in exercise, in catabolic metabolism? | decrease |
How do you get insulin in the muscle cells if insulin is low? | muscle stretches, GLUT4 transporters go to the surface and allow for glucose entry into cells |
How does exercise benefit diabetics? | increased entry of glucose into cells during exercise - GLUT4 transporters move to cell membrane and allow for movement of glucose |
What does cortisol cause? | degradation of fat, muslce, etc. - extremely catabolic. Also causes the liver to produce glucose |
Where does the cortisol drain? | the medulla of the adrenal gland - sympathetic NS causes epi to be secreted in the adrenal |
What does epi do to fat? | causes breakdown of fat, sends fat to liver to be converted to glucose |
What effect does the sympathetic NS have on insulin? | inhibits - no insulin during stress |
What does alpha cells do in the absense of insulin? | alpha cell secretes glucagon |
In stress, which three hormones are present in the plasma? | glucagon, epi, cortisol |
What do glucagon, epi and cortisol do during stress? | mobilize glucose in the blood stream |
How does synergy work during stress? | each hormone increase blood glucose, but putting epi + glucagon + cortisol = a larger effect |
Formula for synergy | 1+1+1 = 5 |
What are types of stress? | exercise, other activation of sympathetic NS, trauma, surgery, dehydration, lack of food |
What part of the body uses ketones as a fuel source? | brain |
What hormone does starvation turn on? | thyroid hormone |
What effect does decrease thyroid hormone have on BMR? | decreased |
What effect does decreased metabolic rate have on body temperature? | decreases |
As fat depots shrink, what happens to leptin levels? | decrease |
What do decreased leptin levels cause? | decreaesd TRH, decreasing blood TSH levels |
What happens to T4 and T3 in starvation? | decrease, switch to T4, rather than T3 |
What happens to appetite during starvation? | increases at first, then decreases |
What happens to melanocortin receptors in low leptin conditions? | receptors inhibited, inhibition of feeding stops - so, you feed |
How does high insulin effect feeding? | Signals to the hypothalamus to stop feeding |
What effect does low insulin have on feeding? | turns on feeding |
High leptin, high insulin | turn off feeding |
low leptin, low insulin | turn on feeding |
When sympathetic nervous system is on, what does this do to insulin? | turns off insulin |
Sympathetic NS - turns off insulin, causes feeding or no feeding? | feeding - hungry b/c of stress! |
Type 1 diabetes causes increased or decreased ketogenesis? | increased |
In severe hypoglycemia, CNS increases output to adrenal and pancrease, increasing blood levels of what? | glucagon and epi |
Hypothyroid, pituitary etiology has what effect on basal metabolism? | Low TSH, low T4 - decreased basal metabolism |