Lecture 9 Flashcards
Integrative and Vascular Responses to Exercise
what are the four ways that active muscle gets more oxygen during exercise
- local vessels dilate due to metabolites
- cardiac output increases
- blood flow redistributed to active muscle
- increased oxygen extracted from each unit of blood
net flow of blood to tissue is a balance of ……. control (2)
intrinsic / local control
extrinsic / global control
what is extrinsic control mainly controlled by
sympathetic nervous system (via NAd and Ad)
what organs receive more blood flow during exercise
heart and muscle
also skin
what are myogenic mechanisms that provide local control of arteriolar tone (also where is this important)
- constrict against pressure (especially renal and cerebral arterioles) - these areas can not be exposed to high pressure
what are the temperature mechanisms that provide local control of arteriolar tone
dilate with heat, constrict with cold
what are the metabolic mechanisms that provide local control of arteriolar tone and why is this important
dilate with increased CO2, H+, K+, adenosine
dilate with decreased pO2
will cause local dilation of arterioles so there can be exchange between the local tissue
what are the key humoral mechanisms that provide local control of arteriolar tone and what is this in response to
nitric oxide : in response to hypoxia and shear stress
- produced by epithelial cells in tissue
histamine : dilate during inflammatory reaction,
how do the mechanisms such as myogenic, temperature, metabolic and humoral operate when controlling arteriolar tone
by negative feedback
what happens when you double the radius in terms of blood flow
when you double the radius you get 16 times the blood flow
what is the purpose of extrinsic control of arteriolar tone
- ensure maintenance of MAP
- ensure adequate perfusion of active tissues, especially during exercise
what is the neural mechanism of extrinsic control of arteriolar tone
neural : sympathetic nervous system, releasing NAd in most arterioles
what is the endocrine mechanism of extrinsic control of arteriolar tone and what do they do
ADH and ANG-II cause constriction
ADH will prevent you from producing as much urine, so will keep your fluid levels up
what is the equation of blood pressure
blood pressure = cardiac output x total peripheral resistance
what does systolic blood pressure estimate
- the work of the heart
- strain against arterial walls
- appropriate cardiovascular function
what does diastolic blood pressure estimate
the total peripheral resistance
what is mean arterial pressure equal to
2/3 DBP + 1/3 SBP
what is the rate pressure product equal to
rate pressure product = systolic blood pressure + heart rate
what does the rate pressure product tell us
the heart oxygen requirements
compare RPP during exercise and rest
RPP ~6000 at rest to ~40,000 during exercise
does blood pressure and heart rate increase more with arm or leg exercise and why
arm = due to cardiac output distribution
what happens to blood pressure, cardiac output and total peripheral resistance during resistance exercise
blood pressure will increase because there is an increase in cardiac output but total peripheral resistance stays relatively the same
short term control of blood pressure at rest is detected by what and causes what
detected by aortic and carotid baroreceptors
causes SNS ans PNS mediated responses
long term control of blood pressure at rest is detected by what and causes what
detected by cardiopulmonary baroreceptors
causes mainly endocrine and renal responses
3 forms of cardiovascular control during exercise
- feedforward central command (dominates early)
- Ergoreceptors important (muscle mechanoreceptors and chemoreceptors)
- baroreceptors (-ve feedback)
