Short term control of blood pressure

Question 1

What does too low of a mean arterial pressure result in?

Answer 1

fainting.
You will end up on the floor and this will remove the effect of gravity on your cardiovascular system.
There will be less pooling in the legs and therefore end diastolic volume will be restored, preload is restored, stroke volume is restored and you regain consciousness

Question 2

What does too high of mean arterial pressure result in?

Answer 2

Hypertension - will increase the risk of coronary heart disease and stroke.

Question 3

What is the role of arterial baroreflex ?

Answer 3

The arterial baroreflex senses change in the mean arterial pressure.

Question 4

What is the role of baroreceptors?

Answer 4

Baroreceptors are strechy. When there is an increase in the pressure, these will strech. Baroreceptros will detect the change in strech and increase the firing rate of action potentials. These are known as stretch receptors. One is found in the carotid sinus and the other is found in the aortic arch.

Question 5

Which nerve do aortic arch receptors send signals up?

Answer 5

Aortich arc receptors send signals up the vagus nerve

Question 6

Which nerve do carotid sinus baroreceptors send signals up?

Answer 6

Carotid sinus baroreceptors send signals up glossopharyngeal nerve

Question 7

What are medullary cardiovascular centres?

Answer 7

Integrating centre is in the medulla oblongata which is the most inferior part of the brain stem.

Question 8

What responses can the medullary cardiovascular centres send to bring the mean arterial pressure back to normal?

Answer 8

• Parasympathetic outflow via the vagus nerve
• Sympathetic nervous system innervates the sinotrial node in the heart.
• Sympathetic nerve that innervate muscles of the ventricles

Question 9

How does the parasympathetic outfloe via the vagus nerve bring mean arterial pressure back to normal?

Answer 9

Parasympathetic outflow via the vagus nerve, innervates the sinotrial node in the heart. Acetylcholine neurotransmitter is released here which will bind to cholinergic muscuranic receptors on pacemaker cells causing them to hyperpolarise, leading to decreased heart rate.

Question 10

How does sympathetic nervous system innervating the sinotrial node in the heart bring the mean arterial pressure back to normal?

Answer 10

Sympathetic nervous system innervates the sinotrial node in the heart. This will then release noradrenaline which will bind to beta 1 receptors and will cause the pacemaker cells to depolarise faster and therefore will cause an increase in heart rate

Question 11

What are other inputs in the medullar cardiovascular centres?

Answer 11

• Cardiopulmonary baroreceptors: Strech receptors. The job is to sense central blood volume
• Central chemoreceptors: sense changes in partial pressure of oxygen and carbon dioxide. Increase the volume of oxygen coming into your lungs and increase mean arterial pressure
• chemoreceptors in the muscle
• Joint receptors
• Input from higher centre: involves hypothalamus and cerebral cortex may be involved

Question 11

How does the sympathetic nerve that innervates the muscles of the ventricle bring the mean arterial pressure to normal?

Answer 11

Sympathetic nerve that innervate muscles of the ventricles increases contractility. There will be increased release of calcium and will cause actin and myosin crossbridges to form and increase the strength of excitation-contraction coupling. Therefore there will be a strong force of contraction and an increased stroke volume. Additionally there will be release of adrenaline and some nonadrenaline from the adrenal medulla into the blood that will circulate again, binding too beta one receptors in the heart and increasing contractility and heart rate.

Question 12

What is the Valsava Manouvre?

Answer 12

This is forced expiration against a closed glottis. It is forceful inspiration with your mouth closed.
This increases thoracic pressure but also has effects on the cardiovascular system