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Controlling MAP
Why do we need to control it?
Short term
Long term
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Vasomotor
Cardioinhibitory
Cardioacceleratory
Brain Centers for Short Term MAP Control
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Increased vasomotor center activity
__creased sympathetic output to arterioles
Vaso__________
__creased peripheral resistance
__creased blood pressure
What about a decrease in vasomotor activity?
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Increased cardioacceleratory center activity
__creased sympathetic output to heart
__creased heart rate and stroke volume
__creased cardiac output
__creased blood pressure
What about a decrease in cardioacceleratory activity?
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Increased cardioinhibitory center activity
__creased parasympathetic output to heart
__creased heart rate
__creased cardiac output
__creased blood pressure
What about a decrease in cardioacceleratory activity?
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Baroreceptor Reflex
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Baroreceptor Reflex Baroreceptors signals the
cardiac and vasomotorcenters via CN IX and X.
Frequency of theseimpulses is proportionalto MAP.
Cardiac and vasomotorcenters adjust theiroutput accordingly.
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MAP rises MAP falls
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Demonstrating the Baroreceptor Reflex
Take the subjects radial pulse. Find the carotid pulse point and GENTLY press
on it.
What will happen to the radial pulse? Why?
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Adrenal Medullary Mechanism
Release epinephrine (and asmall amt of NE) in responseto:
Large drops in MAP. Increases in physical activity. Stressful situations.
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How would activation of the adrenalmedulla affect:
HR SV CO PR BP
Adrenal Medullary Mechanism
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Renin-Angiotensin-Aldosterone System
Renin
Angiotensin II
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Indirect Mechanism
Angiotensin II
Vasoconstriction
Increased TPR
Aldosterone &Antidiuretic
hormone
Thirst
Increased BV
Increased BP
Renin-Angiotensin-Aldosterone System
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In response to a fall in MAP, renin releaseby the kidney would:
In response to a rise in MAP, renin releaseby the kidney would:
Indirect MechanismRenin-Angiotensin-Aldosterone System
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A 25yo woman complains to her doctor of
headaches and blurred vision. Her blood pressure is200/130 mmHg. After the BP has been reduced,investigations are made to find the cause of the
problem. Its discovered that her left renal artery isnarrowed.
Why would this cause the rise in BP?
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Long Term BP Control
Achieved by the...
Primarily done by altering...
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Large increase in BP
____________urine formation
____________urine output
____________blood volume
_________BP
Long Term BP Control
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As we go from theaorta to the
billions of capillaries, what happens to thetotal cross-
sectional area?
What happens tothe velocity of blood flow?
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As we go from thebillions of
capillaries to thevenae cavae, what happens to thetotal cross-
sectional area?
What happens tothe velocity of blood flow?
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The Paradoxical Problem of theVasomotor Center
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Local Regulation of Blood Flow
Autoregulation - adjustment of blood flow toeach tissue according to its immediate needs.
Surplus or deficiency of local chemicals
influences local vessel diameter and blood flow.
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WorkingMuscle Tissue
Tissue CO 2 levels ___
Tissue O 2 levels ___
Tissue temp. ____
Lactic acid levels ___
CO 2 _______
Arteriolesserving tissuevaso________
______bloodflow to tissue
Lactic acid _______
Heat _______ O 2 ________
Local Regulation of Blood Flow
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Capillary Exchange
Btwn blood plasmaand tissue fluid.
Nutrients, wastes,signaling molecules
FLUID
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Capillary Fluid Exchange
4 forces Capillary osmotic pressure.
Capillary hydrostatic pressure.
Interstitial osmotic pressure.
Interstitial hydrostatic pressure.
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Capillary Hydrostatic Pressure
A.k.a
What does it do?
ISFCAPILLARY HP
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Capillary Osmotic Pressure
Mostly due to
What does it do?
ISFCAPILLARY OP
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Interstitial Hydrostatic Pressure
Usually inconsequential b/c What would it do?
ISF HPCAPILLARY
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Interstitial Osmotic Pressure
Usually inconsequential b/c What would it do?
ISF OPCAPILLARY
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Capillary Fluid Exchange
Thebalance of what 2 forces typically determines if fluid enters or exits the capillary?
Net filtration pressure
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Capillary Filtration
If capillary HP >> capillary OP,
What kind of fluid movement will occur?
ISFCAPILLARY
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Capillary Reabsorption
If capillary HP
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Capillary Fluid Exchange Is capillary HP constant??
Is capillary OP constant??
P r e s s u r e
Distance along the capillary
Arterial end Venous end
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Capillary Fluid Exchange At which end of the capillary is filtration likely to occur? At which end is reabsorption likely to occur?
P r e s s u r e
Distance along the capillary Arterial end Venous end
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Capillary Fluid Exchange
Capillary HP usually slightly exceeds capillary OP.
Why does this matter?
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