Cardiovascular System

Question 1

What are the three vessels exiting the aortic arch?

Answer 1

Left subclavian artery
Left common carotid artery
Brachiocephalic artery (right subclavian and common carotid artery)

Question 2

What are the various coronary arteries?

Answer 2

Right: splits into the posterior and marginal arteries
Left: splits into the anterior and circumflex (splits into the posterior and marginal)

Question 3

During systole what happens to the coronary arteries?

Answer 3

Compressed (blood flow stops, continues during diastole)

Question 4

What are end-arteries and what happens if they are occluded?

Answer 4

Terminal arteries supplying all the blood to a tissue without collateral circulation
Anatomical end arteries: no connections or anastomoses
Functional end arteries: connections or anastomoses are not sufficient

Question 5

What happens if coronary arteries are occluded?

Answer 5

Coronary arteries can develop collateral circulation in response to stenosis (narrowing) of the vessels

Question 6

What are the valves of the heart and where are they found?

Answer 6

Atrioventricular valves: prevent backflow of blood into the atrium
Left: bicuspid (mitral)
Right: tricuspid
Semi-lunar valves: prevent backflow of blood into the ventricles
Middle (left): aortic
Anterior (right): pulmonic

Question 7

Where does the wave of depolarisation flow from in the heart?

Answer 7

Flows from the SAN along the internodal tracts (anterior, middle, posterior) to the AVN
Flows from the AVN along the bundle of His (left, right), along the Purkinje fibres, along the terminal filaments to the ventricular walls
Also, SAN sends an impulse along Bachman’s bundle to the left atrium

Question 8

What is the route blood takes from the heart around the body?

Answer 8

Large arteries (elastic vessels)
Medium arteries (muscular vessels)
Arterioles (resistance vessels)
Metarterioles (flow regulators)
Capillaries (exchange vessels)
Post-capillary venules (exchange vessels)
Venules (collection vessels)
Medium veins (capacitance vessels)
Large veins (capacitance vessels)

Question 9

Describe the function of large arteries

Answer 9

Elastic vessels: maintain pressure by returning elastic energy from systole (pressure reservoir)

Question 10

Describe the function of medium arteries

Answer 10

Muscular vessels:

Constrict/relax to regulate blood flow and even out pressure (smooth muscle)

Question 11

Describe the function of arterioles

Answer 11

Resistance vessels:
Slow down blood flow
Constrict/relax to regulate blood flow and decrease pressure (smooth muscle)

Question 12

Describe the function of metarterioles

Answer 12

Flow regulators:

Control flow of blood to capillaries and tissues (pre-capillary sphincter)

Question 13

Describe the function of capillaries

Answer 13

Exchange vessels:
Allow efficient diffusion through single endothelium layer
Slow down blood (lumen 1 wide)

Question 14

Describe the function of post capillary venules

Answer 14

Exchange vessels: (more permeable than capillaries)
Allow fluid to drain back
(Immune cells leave during inflammatory response via these vessels)

Question 15

Describe the function of venules

Answer 15

Collection vessels:

Contain valves for uni-directional flow of blood (drain blood from post-capillary venules into veins)

Question 16

Describe the function of veins

Answer 16

Capacitance vessels:

Hold larger volume of blood at lower pressure (thin walls, large lumen)

Question 17

Describe the layers of a vessel

Answer 17

Tunica externa: connective tissue and vasa vasorums
(External elastic membrane)
Tunica media: smooth muscle and elastic fibres
Tunic intima: endothelium and connective tissue
(Internal elastic membrane)
Lumen

Question 18

Describe the differences between arteries and veins in terms of structure

Answer 18

Arteries:
Thin tunica externa
Thick tunica media

Veins:
Thick tunica externa
Thin tunica media

Question 19

How is blood returned to the heart?

Answer 19

Blood from the lower limbs is returned by muscle contractions
Pressure in the core is sufficient to return blood (vertical gradient of venous pressure)
There are valves within the veins of the limbs to prevent backflow