Circulation of Blood

Question 1

What are the functions of the cardiovascular system?

Answer 1

Bulk flow of materials (gases, nutrients, hormones and waste), Temperature regulation, homeostasis, host defence and reproduction.

Question 2

Breifely describe the regulation and integration of the CVS from the CNS

Answer 2

The CNS controls the CVS via autonomic nerves and hormones. As well as the respiratory and renal systems

Question 3

Why is the wall of the left ventrical more muscular to than the right?

Answer 3

The left ventrical bumps blood out to the whole body so more muscle is required to generate a greater force whereas the right ventrical only pumps blood to the lungs to it requires less force.

Question 4

What does the parallel arrangement of the CVS allow?

Answer 4

Independant regulation of blood flow to organs. It allows for adaptation to the metabolic demands of the tissue.

Question 5

At rest what is the rate of blood flow through any vessel

Answer 5

5 liters/min

Question 6

Breifly describe the direction of blood flow

Answer 6

Vene cava to right atrium to right ventricle to pulmonary trunk to pulmonary arteries to lung capillaries to pulmonary veins to left atrium to left ventricle to aorta to arteries to arterioles to capillaries to venules to veins and finally back to VC

Question 7

Name the microvessels

Answer 7

Arteriole, terminal arteriole, capillary and venules. measured in micrometers.

Question 8

Describe a features of arterioles

Answer 8

Smallest diameter of muscular walled arteries

Question 9

Describe features of precapillary sphincters

Answer 9

Rings of smooth muscle which control the entry of blood from arteriole into each capillary

Question 10

Describe features of capillaries

Answer 10

They are the smalled diameter of BV (1 endothelial cell thick). This allows for diffusion of nutrients and waste

Question 11

Describe features of venules

Answer 11

Smallest diameter veins which drain blood back to larger true veins.

Question 12

Name the valves of the heart

Answer 12

Tricuspid valve, pulmonary valve, mitral valve (bicuspid) and aortic valve.

Question 13

Describe features of the atrioventricular valves

Answer 13

All valves open passively. Cuspid valvis are fairly flimsy and attached to chordae tendineae which are attached to papillary muscles, these prevent pressure forcing the valve open.

Question 14

Describe features of the semiluminar valves

Answer 14

Aortic and pulmonary valves. Both are tricuspid but are more heavy duty. They have smaller openings but the higher pressure of blood leads to more stress and physical abrasion.

Question 15

Describe the structure of cardiac muscle

Answer 15

• Small striated fibers, which are branched. - They are connected by desmosomes at the intercalated discs.
• Gap junctions allows the passage of ions resulting in functional syncitium

Question 16

Describe the functional syncitium of cardiac muscle

Answer 16

Because cells of atrial myocardium are electrically connected via gap junctions it means the cells depolarise and contract synchronously. Ventricals are similar

Question 17

What percentage of cardiac cells don’t contract, what is their function?

Answer 17

1%. they form the excitatory and conductive muscle fibres

Question 18

Describe the pacemaker activity and its autonomic innervation

Answer 18

Sinoatrial node (SAN) is the intrinsic pacemaker. SNS increase the rate of SAN depolarisation where as PSNS decreases the rate of SAN depolarisation