Short term regulation of mean arterial blood pressure.

Question 1

How do you calculate the mean arterial blood pressure? There are two ways of doing this.

Answer 1

Diastolic arterial pressure + 1/3 of pulse pressure.

Mean arterial blood pressure = cardiac output x total peripheral resistance.

Question 2

What is the main mechanism used to change blood pressure in the CVS?

Answer 2

Changing the TPR of the arterioles; diameter.

Question 3

Explain the mechanism of the control of arteriolar diameter.

Answer 3

There is always a level of muscular tone maintained in the smooth muscle lining the blood vessel. VASOMOTOR TONE. The sympathetic system causes the contraction of this muscle while the parasympathetic system causes relaxation and hence dilation of the vessel.

Question 4

Normally there is no significant parasympathetic supply to a blood vessel. Provide an example where this is an exception.

Answer 4

To the arterioles in the genitals.

Question 5

Describe 3 mechanisms which control vasomotor tone.

Answer 5

Neural (baroreceptor reflex),

Local,

Hormonal.

Question 6

Describe the baroreceptor reflex.

Answer 6

Decreased MAP will reduce STRETCH on the basoreceptors causing increased sympathetic activity to the heart and blood vessels.