Introduction to CVS Physiology

Question 1

State the functions of the CVS

Answer 1

To deliver O2 and nutrients to cells
To remove CO2 and metabolites from cells
Heat
Hormone transport.

Question 2

How is output from the CVS variable?

Answer 2

Can vary from 5-30l/min

Vessels can redirect or store blood

Question 3

How is pulmonary circulation described as being in series?

Answer 3

Because blood is pumped through one vessel (the pulmonary artery) and then another vessel (the pulmonary vein), therefore output must be equal.

Question 4

State the other circulation that is in series

Answer 4

Between the hypothalamus and the anterior pituitary gland

Question 5

How is circulation between the left heart and the organs of the body in parallel?

Answer 5

Because all the organs receive blood at the same time (but blood can be redirected as required by arterioles)

Question 6

Explain portal and systemic supply to the liver

Answer 6

Blood is pumped to the liver from systemic circulation, however, the liver also receives deoxygenated blood from the gut’s capillary bed to its own capillary bed via the hepatic portal vein.

Question 7

Describe the structure and function of elastic arteries e.g. aorta

Answer 7

Thick elastic wall dampens pressure variations.

Wide lumen and elastic wall release elastic tension.

Question 8

Describe the structure and function of muscular arteries

Answer 8

Pump blood to regions of body.

Wide lumen and non-elastic muscular arteries act as low resistance conduit.

Question 9

What type of artery has a low resistance conduit?

Answer 9

Muscular arteries

Question 10

What vessels are called resistance vessels? Why?

Answer 10

Arterioles. Act as taps. Narrow lumen and contractile wall allows to control resistance and thus flow allowing regional redirection of blood.

Question 11

What is the equation for flow?

Answer 11

Flow = Change in pressure (MAP-CVP)/Resistance (r^4).

Question 12

What is the relationship between radius and resistance?

Answer 12

Increase radius, reduce resistance.

Question 13

Describe the structure and function of capillaries

Answer 13

Gas exchange vessels.

Thin wall and narrow lumen

Question 14

What vessels are called capacitance vessels? Why?

Answer 14

Venules and veins. Wide lumen and distensible walls allow for storage of up to 2/3 of blood. Structure allows regional distribution of blood between veins and other vessels plus heart,

Question 15

What proportion of the body’s blood can be stored by capacitance vessels?

Answer 15

Venules and veins up to 2/3 of total blood

Question 16

Describe the route of blood though the heart

Answer 16

Deoxygenated blood from systemic circulation enters the heart via the SVC and IVC. It enters the right atrium and flows through the tricuspid valve before entering the right ventricle. It then flows through the pulmonary semilunar valve into the pulmonary trunk and then either the left or right pulmonary artery.

Blood is oxygenated I n the capillaries of the lungs before it enters the left and right pulmonary veins and into the left atrium. It then passes through the bicuspid or mitral valve into the left ventricle. it travels through the aortic semilunar valve into the aorta and then travels to cells via the arterial system

Question 17

Name the valve between the right atrium and ventricle

Answer 17

Tricuspid valve

Question 18

What chambers does the bicuspid or mitral valve sit between?

Answer 18

Left atrium and ventricle

Question 19

What kind of valve is between the left ventricle and the aorta?

Answer 19

Aortic semilunar valve

Question 20

What structures does the pulmonary semilunar valve sit between?

Answer 20

Right ventricle and the pulmonary trunk