The Vasomotor Control Centre Learning Objectives… 1)To understand how the VCC affects the cardiac cycle. 2)To understand how vascular shunting affects SV/Q/HR.

The vasomotor control centre found in the medulla oblongata of the brain. What else is located in the medulla oblongata?

The Vasomotor Control Centre Chemoreceptor's and baroreceptors stimulate the VCC. What do they detect?

The Vasomotor Control Centre VCC stimulates the sympathetic nervous system which control blood vessel lumen diameter of organs and muscles. Why would your blood vessels need to get bigger? Blood Vessel

The Vasomotor Control Centre Vasodilatation = The widening of blood vessels lumen Vasoconstriction = The narrowing of blood vessels lumen Vasoconstriction Vasodilatation

Question… How does the Vasomotor control centre link to the cardiac control centre, conduction system and cardiac cycle?

The Vasomotor Control Centre Vascular Shunting….. Describes the redistribution of blood How would this be different at rest and during the onset of exercise?

Vascular Shunting At rest 20 % (approx) of your blood is located at your muscles and 80% is located in your organs. During exercise (depending on the intensity) 80 % (approx) of your blood is located at your muscles and 20% is located in your organs. Plot this information on your graph

Vascular Shunting Cardiac Output At restExercise Muscles Organs 80% 20%

Vascular Shunting So we now know that blood is moved around our body when we go from rest to exercise. Use your textbooks…can you find out what controls the blood flow in/out of muscles and organs?

Vascular Shunting Blood flow to the organs/muscles is controlled by the VASOCONSTRICTION/VASODILATION OF ARTERIOLES & PRE CAPILLARY SPHINCTERS. The precapillary sphincter is a band of smooth muscle that adjusts the blood flow into each capillary. The arteriole 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 MECHANISM During the onset of exercise INCREASED STIMULATION OF SYMPATHETIC NERVES VASOCONSTRICTION OF ARTERIOLES & PRE CAPILLARY SPHINCTERS What happens at your ORGANS What happens at your MUSCLES DECREASED STIMULATION OF SYMPATHETIC NERVES VASODILATION OF ARTERIOLES & PRE CAPILLARY SPHINCTERS