Test 4 study guide thingy Flashcards
what is signal transduction?
-ligand receptor interaction causes a response in the target cell called signal transduction
what controls the effectiveness and concentration of a hormone? does this change during exercise?
- the number of receptors available for binding
2. blood hormone concentration
blood hormone concentration determined by
- rate of secretion from the endocrine gland
- rate of metabolism or excretion of hormone
- quantity of transport protein
- changes in plasma volume
what happens to plasma volume during exercise?
during exercise, plasma volume decreases which causes a slight increase in hormone concentration in plamsa
what are the three effects elicited by a hormone receptor interaction?
- alter membrane transport
- stimulate DNA to increase proteins synthesis
- activates second messengers (cyclic AMP and CA++)
are steroid hormones lipophobic or lipophilic, and what does this mean with respect to carrier molecules?
steroid hormones cross the cell membrane very easily, meaning they are lipophilic. The carrier moleucles don’t have to increase intracellular concentration of ions or substrates
what are some examples of second messengers?
phosphorylase hormone sensitive lipase g protein diacylglycerol inositol triphosphate cyclic AMP Ca++
what are the main endocrine systems we described in class?
- hypothalamus
- posterior pituitary
- anterior pituitary
- thyroid
- adrenal glands
- pancrease
- testes
- adipose tissue
- skeletal muscle
hypothalamus
regulator of the pituitary
-influence by + and - input
anterior pituitary gland
- true endocrine gland
- secretes growth hormone which aids in the maintenance of blood glucose
posterior pituitary gland
- secretes ADH (vasopressin) and oxytocin
- it reduces water loss
- stimulated by high plasma osmolality and low plasma volume due to sweating, and exercise
thyroid
T3 and T4 maintain metabolic rate
- T4:T3 is 20:1
- T4 can be converted into T3
- increases metabolic rate
- The thyroid gland is very slow
- secretes calcitonin and pTH
what is the actual % of people with hypothyroid?
3-4%
calcitonin
regulates Ca++
adrenal gland
secrete 80% epinephrine and 20% norepinephrine
-it increases HR, glycogenolysis, lipolysis, and BP
where is growth hormone secreted from? what does it do?
- secreted from the anterior pituitary gland
- stimulates protein synthesis and long bone growth
- mobilized free fatty acid from adipose tissue
- aids in the maintenance of blood glucose
- growth hormone increases during exercise*
what is ADH and how does its concentration change during exercise?
ADH = antidiuretic hormone
- reduces water loss to maintain plasma volume
- stimulated by high plasma osmolality and low plasma volume due to sweating and exercise
- * ADH increases at 60% VO2 max***`
what does the adrenal medulla secrete? are these agents slow or fast acting?
- adrenal medulla secretes epinephrine and norepinephrine
- they are fast acting due to the fight or flight response
- it increases HR, glycogenolysis, lipolysis, and BP
what does the adrenal cortex secrete?
mineralcorticoids (aldosterone) glucocorticoids (cortisol) sex steroids (androgens and estrogens)
what stimulates the release of aldosterone? What is the aldosterone response to exercise?
the adrenal cortex secretes mineral corticoids (aldosterone)
- plasma k+ is the direct controller as well as Ang II (increased k+ induce secretion of aldosterone)
- little exercise: little change in aldo and renin and Ang II
- heavy exercise: (>50% VO2 max) parallel increases in aldo, renin and Ang II
- as plasma K+ increases aldosterone does as well
what stimulates the secretion of cortisol?
stimulated by exercise and long term fasting (to maintain plasma glucose)
how is the regulation of muscle glycogen utilization altered with exercise?
high intensity and duration exercise results in a more rapid glycogen depletion
- not greater but faster
- the heavier the exercise, the faster the glycogen is depleted
- * greater at 90 min @ 75% VO2 max than 30 min at 90% VO2 max*
during exercise what are permissive hormones
- they are helper and facilitator hormones
- without T3, epinephrine has little effect on FFA mobilization from adipose tissue, so T3 is a permissive hormone
does plasma growth hormone change with increasing exercise intensity?
as intensity increases, so does the levels of plasma growth hormone
-maximal work is >25x resting value (more sensitive with aerobic training)
does endurance training alter plasma norepinephrine or epinephrine levels to a fixed workload?
endurance training causes a rapid decrease In plasma NE and E to a fixed workload. YES.
what happens to FFA mobilization in light/moderate exercise versus heavy/sever exercise?
FFA mobilization decreases during heavy exercise
- doesn’t decrease in light/moderate exercise
- possibly because of high levels of lactic acid, elevated H+, or inadequate blood flow
what is the tolerated variation in core temperature and what effects does getting near temperature thresholds have on the body?
normal core: 37 C
too hot: 45 C or 113 F this may denature proteins and enzymes and lead to death
too cold: 34 C or 93.2 F: this may cause slowed metabolism and arrythmias
what are the mechanisms of involuntary heat production?
- shivering
- action of hormones :T3 and catacholamines
what are the predominant mechanisms in which we lose heat at rest? Does the contribution from these mechanisms change during exercise?
Radiation-
conduction
convection
evaporation
radiation
transfer of heat via infared rays
- no physical contact between surfaces
- 60% heat loss at rest
conduction
heat loss due to contact with another surface
convection
form of conductive heat loss
-heat transferred to air or water
evaporation
- heat transferre via water (sweat) on skin surface.
- depends on temp and relative humidity
- 25% heat loss at rest
- maximal sweat rate: 1.5 L/hr. After acclamation, 3.5 L/hr. Cooling power: 600 calories/L
What is the bodies thermostat in response to heat?
the hypothalamus is the body’s thermostat
- anterior pituitary increases core temp, sweating, increased blood flow
- posterior pituitary: cold exposure, heat production, shivering, decrease skin blood flow
anterior hypothalamus
works with heat exposure
-increased core temp, sweating, increase skin blood flow (vasodilation)
posterior hypothalamus
cold exposure, heat production (shivering), non shivering thermogenesis (T3 and catacholamines), decrease skin blood flow (vasoconstriction)
during a heat stress, how does the body attempt to regulate temperature? how can the effects of trying to regulate core temperature in a hot environment impact exercise?
Heat load: vasodilation and sweating
cold: shivering, vasoconstriction, catecholamine release and thyroxin release
-in a hot environment exercise could have impaired performance, and hyperthermia. Earlier onset of muscle fatigue
how can exercising in a hot/humid environment effect the onset of fatigue or impair performance?
there is an earlier onset of fatigue by -reduced mental drive, -reduced muscle blood flow during high intensity exercise, -accelerated glycogen metabolism,
- accelerate production of free radicals
- useless water loss
- higher core temp and sweat rate
How does the body acclimate to heat, and is this a slow (months) or a fast (days) response?
- adaptions occur within 7-14 days
- 10-12% increase in plasma voume
- increased sweat rate (can double)
- decreases salt loss in sweat
- increase in the synthesis of heat shock proteins (induced by increased temp- they are protective proteins)
with decreasing barometric pressure, what happens to the composition of air? in other words, what happens to the fraction (%) and density of O2, N2, CO2, etc. with increasing altitude?
less molecules as altitude increases, but same % of O2 N2 Ar CO2. the % do not change