The Vasomotor Control CentreThe Vasomotor Control Centre

Learning Objectives…Learning Objectives…

1)1) To understand how the VCC affects the To understand how the VCC affects the cardiac cycle.cardiac cycle.

2)2) To understand how vascular shunting affects To understand how vascular shunting affects SV/Q/HR. SV/Q/HR.

TheThe vasomotor control vasomotor control centrecentre found in the found in the medulla oblongatamedulla oblongata of the brain. of the brain.

What else is located in the medulla oblongata?What else is located in the medulla oblongata?

The Vasomotor Control CentreThe Vasomotor Control CentreChemoreceptor'sChemoreceptor's and and baroreceptors baroreceptors

stimulate the VCC.stimulate the VCC.W

hat do they detect?

The Vasomotor Control CentreThe Vasomotor Control CentreVCC stimulates the VCC stimulates the sympathetic sympathetic

nervousnervous systemsystem which control blood which control blood vessel lumen diameter of organs and vessel lumen diameter of organs and

muscles.muscles.

Why would your blood vessels need to get bigger?

Blood Vessel

The Vasomotor Control CentreThe Vasomotor Control CentreVasodilatation = The widening of blood vessels lumenVasodilatation = The widening of blood vessels lumen

Vasoconstriction = The narrowing of blood vessels lumenVasoconstriction = The narrowing of blood vessels lumen

Vasoconstriction

Vasodilatation

Question…Question…

How does the How does the Vasomotor control Vasomotor control centrecentre link to the link to the cardiac control cardiac control centrecentre, , conduction systemconduction system and and

cardiac cyclecardiac cycle??

The Vasomotor Control CentreThe Vasomotor Control Centre

Vascular Shunting…..Vascular Shunting…..

Describes the redistribution of bloodDescribes the redistribution of blood

How would this be different at rest How would this be different at rest and during the onset of exercise?and during the onset of exercise?

Vascular ShuntingVascular ShuntingAt rest At rest 20 %20 % (approx) of your blood is located (approx) of your blood is located

at your muscles and at your muscles and 80%80% is located in your is located in your organs.organs.

During exercise (depending on the intensity) During exercise (depending on the intensity) 80 80 %% (approx) of your blood is located at your (approx) of your blood is located at your muscles and muscles and 20%20% is located in your organs. is located in your organs.

Plot this information on your graphPlot this information on your graph

Vascular ShuntingVascular ShuntingC

ard

iac

Out

pu

t

At rest Exercise

Muscles

Organs

80%

20%

Vascular ShuntingVascular ShuntingSo we now know that blood is moved around So we now know that blood is moved around

our body when we go from rest to exercise.our body when we go from rest to exercise.

Use your textbooks…can you find out what Use your textbooks…can you find out what controls the blood flow in/out of muscles and controls the blood flow in/out of muscles and

organs?organs?

Vascular ShuntingVascular ShuntingBlood flow to the organs/muscles is controlled Blood flow to the organs/muscles is controlled by the VASOCONSTRICTION/VASODILATION by the VASOCONSTRICTION/VASODILATION

OF OF ARTERIOLESARTERIOLES & & PRE CAPILLARY PRE CAPILLARY SPHINCTERSSPHINCTERS..

The The precapillary sphincterprecapillary sphincter is a band of smooth is a band of smooth muscle that adjusts the blood flow into each muscle that adjusts the blood flow into each

capillary.capillary.The The arteriolearteriole is a smaller version of an artery. is a smaller version of an artery.

DECREASED BLOOD FLOW (Q) TO CAPILLARIES OR NON

ESSENTIAL ORGANS

INCREASED BLOOD FLOW (Q) TO CAPILLARIES OR WORKING

MUSCLES

VASCULAR SHUNT MECHANISMDuring the onset of exercise

INCREASED STIMULATION OF SYMPATHETIC NERVES

VASOCONSTRICTION OF ARTERIOLES & PRE CAPILLARY

SPHINCTERS

What happens at your

ORGANS

What happens at your

MUSCLESDECREASED STIMULATION OF

SYMPATHETIC NERVES

VASODILATION OF ARTERIOLES & PRE CAPILLARY SPHINCTERS