blood flow images 2

8/2/2019 Blood Flow Images 2

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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


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


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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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 HP usually slightly exceeds capillary OP.

Why does this matter?


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