Chapter 5: Hormonal Responses to Exercise Flashcards
GH location of synthesis
anterior pituitary
stimulus for GH release
*exercise, sleep, stress, low BG
actions of GH
anabolic hormone, promotes muscle hypertrophy
how does GH change for prolonged exercise? graded exercise?
increased duration increases GH, increased intensity increases GH
catecholamines site of synthesis
adrenal medulla
stimulus for catecholamine release
flight or fight response
how does catecholamine levels change for prolonged exercise? graded exercise?
increased duration increases NE & Epi, increased intensity increases NE & Epi
how do levels of NE and Epi change with training?
NE & Epi decrease at the same given work rate with training
cortisol location of synthesis
adrenal cortex
stimulus for cortisol release
*exercise, stress, bone breaks
how do cortisol levels change with exercise?
increased intensity increases cortisol levels
glucagon site of synthesis
pancreas
stimulus for glucagon release
decreased BG
how do blood glucagon levels differ for trained and untrained athletes during prolonged exercise?
untrained individuals see a larger percent increase in glucagon levels (using more glycogen) whereas trained individuals do not see a percent increase in glucagon levels over time at the same intensity
insulin site of synthesis
pancreas
stimulus for insulin release
increased BG
how do NE and Epi affect the hormones secreted by the pancreas?
stimulate glucagon secretion and inhibit insulin secretion
how do insulin levels change with prolonged exercise? graded exercise?
increased duration decreases insulin, increased intensity decrease insulin
which hormones increase circulating BG
glucagon, GH, cortisol, NE/Epi
adequate glucose during exercise requires:
1) glucose release by the liver
2) glucose uptake by muscles
actions of catecholamines
1) increase glycogenolysis at the liver & muscle (muscle glycogen used first) via B1 ADR
3) stimulates glucagon release and inhibits insulin release
2) increase lipolysis in adipose tissue
actions of glucagon
1) increases glycogenolysis and gluconeogenesis at the liver
2) lipolysis in adipose tissue
actions of GH
1) gluconeogenesis in liver
2) lipolysis in adipose tissue
actions of cortisol
1) gluconeogenesis in the liver
2) lipolysis in adipose tissue
how does glucose uptake remain high during exercise with lower insulin levels?
cellular insulin sensitivity is increased & there is increased blood flow and increased insulin delivery to active muscles despite lower concentration
actions of insulin
1) stimulates glucose uptake in muscle cells via translocating GLUT4 transporters
how does exercise increase glucose uptake independently of insulin?
exercise (contractions of muscles) translocate GLUT4 transporters to the membrane
what 4 factors drive fat utilization down as exercise intensity increases (even though hormones are increasing lipolysis)
1) elevated H+ concentration inhibits hormone sensitive lipase (needed for fat mobilization)
2) high levels of lactic acid promotes resynthesis of triglycerides
3) inadequate blood flow to adipose tissue
4) insufficient albumin to transport FFA in plasma
how does plasma volume change with exercise?
increased hydrostatic pressure (BP) –> fluid push out into interstitial space (+ water loss via sweating) –> decreased blood volume & decreased blood pressure –> increases heart strain
vasopressin site of synthesis
hypothalamus
stimulus for vasopressin release
decreased plasma volume or decreased MAP
actions of vasopressin
increases water absorption by kidneys by inserting aquaporins into the membrane
how does vasopressin change with exercise?
increased exercise intensity increases vasopressin
aldosterone site of synthesis
adrenal cortex
stimulus for aldosterone release
decreased plasma volume
actions of aldosterone
increases Na+ and decreases K+ reabsorption in kidney, which causes water to follow the Na+
how do aldosterone levels change with exercise?
aldosterone increases with exercise
why does plasma volume continue to decrease with exercise even though vasopressin and aldosterone increase?
these hormones act at the kidneys, which receive decreased blood flow during exercise
which is used first, muscle glycogen or liver glycogen?
muscle glycogen
does blood glucose concentration change significantly during exercise?
no, because we are inhibiting glucose uptake in some areas (& promoting glycogenolysis and gluconeogenesis) but we are promoting glucose uptake at the active tissues
why is there only a decrease in FFA mobilization during high intensity exercises rather than longer duration exercises?
factors such as H+ levels, lactic lacid, and insufficient albumin aren’t an issue in steady state exercise
