exercise Flashcards
outline the pathway of exercise to dilation of skeletal muscle arterioles via epinephrine
- exercise
- increase sympathetic outflow to adrenal medulla
- release of epinephrine
- acts on B-2 receptors
- dilation of skeletal muscle arterioles
what is central command and what initiates it
central command is a series of responses by the motor cortex initiated by the anticipation of exercise
what processess does central command initiate
- sympathetic outflow to the heart and BV
- decreased PNS outflow to the heart
- increased muscle sympathetic nerve activity
- allows for graded increases in ventilation
stimulation of exercise pressor reflex afferent fibers has what affect?
increases sympathetic nerve acitivity to:
- induces elevation in HR
- elevation of BP
stimulation of exercise pressure reflex receptors generates somatosensory signals which are transmitted to CNS via which afferent fibers
- thinly myelinated group III
- unmyelinated group IV
increase in CO is met by increases in both HR and SV up to what capacity?
- 50 capacity (VO2max)
- at near maximal workloads, HR is still on the rise, where as SV levels off and begins to drop
what is the equation to approximate maximal HR
HR max = 220 - age (years)
why does stroke volume increase with exercise?
- increased venous return
- enhanced LV filling
- heightened contracitility by sympathetic stimulation
what affect does exercise have on EDV and ESV
- increases end-diastolic volume
- decreases end systolic volume
what is VO2 max
maximal capacity for oxygen consumption during exercise
what is the equation for VO2 max
VO2max = HR x SV x arterial venous difference
oxygen uptake is proportional to work performed, up to what?
maximal work capacity (VO2 max)
what is dynamic exercise
repeated voluntary muscle movements in which there is alternate contraction and relaxation of the muscle
- aerobics, swimming, cross country skiing
what is static exercise
refers to state in which the muscle is kept in continued contraction
- bench press, lifting
what happens to systolic BP, diastolic BP, and pulse pressure in dynamic exercise
- systolic pressure increases
- diastolic pressure decreases
- pulse pressure increases
what happens to MAP in dynamic exercise
no change
what happens to CO, HR, and SV in dynamic exercise
- increase in CO is met by an increase
- in HR
- in SV
what happens to systolic, diastolic, and pulse pressure in static exercise
- systolic pressure increases
- diastolic pressure increases
- pulse pressure does not change
what happens to MAP in static exercise
MAP increases
what happens to CO, HR, and SV in static exercise
- CO increases and is met by an increase in HR only
- SV does not change
- static effort impedes venous return and preload
what motions initiate the valsalva maneuver?
- coughing
- defecation
- heavy lifting
describe the valsalva maneuver
- expire against closed glottis
- increase in intrathoracic Pressure
- decrease in venous return to heart
- decrease stroke volume
- decrease in arterial pressure
- decrease in arterial pressure is sensed by baroreceptor and NTS
- increase in SNS and decrease in PNS to heart and BV
- increase in HR
at rest, sympathetic vasoconstriction tone is low or high?
high
- muscle can increase its own blood flow by withdrawal of tone
neural control of skeletal muscle at rest (want increased basal vascular tone) is done via what neurotransmitters and receptors
- increase in sympathetic a-1 adrenergic tone with NE
- decrease in sympathetic B-2 adrenergic tone with epinephrine
neural control of skeletal muscle circulation with exercise (want decrease in vascular resistance) uses what neurotransmitters and receptors
- decrease in sympathetic a-1 adrenergic tone
- increase in muscarinic tone via acetylcholine
- increase in sympathetic B-2 adrenergic tone
active hyperemia to exercise muscle groups is driven by what metabolites
- lactate
- adenosine
- K+
what happens to insulin release during exercise
insulin release is suppressed
- promotes lipolysis and hepatic glucose production
