Physiology Revision - Integrated Cardiovascular response

Question 1

What is a regular sequence for homeostasis of BP for example?

Answer 1

Sensor (baroreceptors) - Control Center (Medulla) with a regular set-point - Effector (alters vasodilation/constriction and HR) - Effector Response - Regulated variable (MAP)

Question 2

What is a baroreceptor?

Answer 2

A type of mechanoreceptor that senses BP through vascular wall changes ie. arterial pressure changes

Located: Aortic arch in the heart, carotid artery

Increased arterial pressure = increased firing of baroreceptors which means afferent nerves cause an increase in parasympathetic nerve activity and a decrease in sympathetic nerve activity to the heart and vasculature + Vasodilation occurs.

Question 3

What would be the cardiovascular response to a hemorrhage? (Bleeding)

Answer 3

• MAP drops
• Baroreceptors decrease firing
• Sympathetic nerve activity to the heart and vasculature occurs, decrease in parasympathetic activity
• Increased HR and vasoconstriction
• Ventricular contractility increases due to increased sympathetic activity to ventricular myocardium
• Arteriolar constriction due to increased sympathetic activity to the arterioles (increased concentration of angiotensin 2 and vasopressin)
• Increased venous constriction because of increased sympathetic activity to veins

Net result - CO increases and TPR increases, causing MAP to return to normal

Question 4

What are the 3 mechanisms for control of ventilation?

Answer 4

1. Initial rise rapid rise in ventilation is explained by central command
2. Mechanoreceptors in muscles and limbs detect limb movement to further supplement central command
3. Subsequent gradual rise in ventilation is due to respiratory neurons in response to central command and feedback control from arterial chemoreceptors in carotid and aortic bodies

Question 5

What are the 3 mechanisms for control of CO?

Answer 5

1. Initial rise in CO explained by central command and Starling effect
2. Input from mechanoreceptors in muscles
3. Chemoreceptors in muscle mainly responsible for secondary gradual rise to steady state

Question 6

What is the Metaboreflex?

Answer 6

Metaboreceptors detect metabolite concentrations in muscle and relay info to the medulla to increase or decrease sympathetic/parasympathetic activity

Question 7

What part of the brain is the primary cardiovascular control center?

Answer 7

Medulla Oblongata

Question 8

How does venous return increase?

Answer 8

• Muscle pump
• Respiratory pump
• Sympathetic stimuli

Question 9

During exercise, BF increases and decreases to:

Answer 9

Increases:

• Skeletal muscle
• Skin
• Heart

Deceases:

• Kidneys
• Digestive Tract
• All parts of the body not directly involved in exercise