Overview of CVS function

Question 1

What does MAP stand for?

Answer 1

Mean Arterial Pressure

Question 2

What does CVP stand for?

Answer 2

Central Venous Pressure

Question 3

The cVS is a ……… flow system

Answer 3

bulk

Question 4

What does the CVS move around?

Answer 4

CO2, O2, nutrients, waste, metabolites, immune cells, hormones, heat

Question 5

Right and Left side of heart are in parallel/series? What does that mean about the output of the R/L side? What would happed if there was a problem with this?

Answer 5

In parallel. This means that the output on the R side must equal the output on the L side, otherwise blood will either pool in the pulmonary circulation or the systemic circulation.

Question 6

Vascular beds in series/parallel? What are the advantages of this?

Answer 6

In parallel, means that each section of the body receives freshly oxygenated blood, also able to redistribute the proportion of blood that goes to each part of the body, eg more to legs when exercising.

Question 7

Which vascular beds are in series and why?

Answer 7

Gut and liver, because there are a lot of nutrients that come from the gut that are passed onto the liver. The liver also has it’s own extra blood supply via portal system.

Question 8

Total CO at rest?

Answer 8

5L

Question 9

What % to brain? Heart? Skeletal muscle? Skin? Kidney? Abdominal organs? Other? Why to these places?

Answer 9

13%, 4%, 20%, 9%, 20%, 24%, 10%. Generally to match the oxygen requirements of the organs/tissues.

Question 10

Why does the kidneys receive 20% blood but only have 6% oxygen requirement?

Answer 10

Because it is the kidneys job to filter out the blood so to do its job well needs blood flowing through it!

Question 11

(Dracy’s law) Flow = ?

Answer 11

Change in pressure/ resistance

Question 12

Pressure difference =

Answer 12

Mean Arterial Pressure (MAP) - Central venous pressure (CVP)

Question 13

Which vessels dilate/constrict to vascular beds? What are they also known as?

Answer 13

The arterioles. They are also known as resistance vessels (as they can change their resistance)

Question 14

What is capaticance? Capacitance vessels?

Answer 14

Capacitance is the ability of a vessel to hold blood. The veins are good at this and so they are known as capacitance vessels.

Question 15

What is the fractional distrrubution of blood?

Answer 15

The percentage of total blood in the body that is in the veins vs the arteries. The amount within the veins can change (eg decrease whilst doing exercise). by constricting or dilating venules/veins to expel some of the capacitance of blood they contain towards the heart.

Question 16

What are the 2 elastic arteries? What is an elastic artery features?

Answer 16

The Aorta and Pulmonary Trunk

V wide lumen (low resistance), thick wall cont. lots of elastin and therefore is elastic. - imp. to dampen down the pressure variations from the heart.

Question 17

What type of vessels are arteries? Why?

Answer 17

Muscular arteries - wide lumen, strong (muscular) non-elastic wall to maintain pressure - low resistance conduit (pipes)

Question 18

What type of vessels are the arterioles? How are they differentiated?

Answer 18

Ressistance vessles. Differentiated by their narrow lumen. Still have thick muscular wall which can control resistance and therefore flow, allowing regional redirection of blood.

Question 19

What are the exchange vessels called, how thick are the walls? What are the advantages?

Answer 19

Capillaries. Walls are v thin (1 cell thick, 1 layer of endothelial cells) to allow diffusion of substances across, and big surface area to volume ratio.

Question 20

Features if venules/veins, what are they also known as?

Answer 20

Capacitamce vessels, wide lumen, walls are collapsible and dispensable. 2 functions: Low resistance conduit to get blood back to the heart, and reservoir for blood (capacitance)

Question 21

What does the septum do?

Answer 21

Divides the left and right sides of the heart

Question 22

What is the myocardium? Which side is thicker?

Answer 22

The heart muscle (wall of the heart)

Question 23

What does the pulmonary trunk leave from?

Answer 23

Right ventricle

Question 24

Valves : leaving left ventricle

Answer 24

Aortic valve (! - enters the aorta)

Question 25

Leaving right ventricle

Answer 25

Pulmonary valve (shock horror - enters the pulmonary trunk)

Question 26

What are aortic and pulmonary valves also known as?

Answer 26

Semi-lunar valves

Question 27

What valve between atrium and ventricles?

Answer 27

On right side (right atrium to right ventricle) = Tricuspid valve (3 cusps)

On left side(left atrium to left ventricle) = Mitral valve (2 cusps)

Question 28

What makes the valves open/shut?

Answer 28

Passive pressure of blood moving.

Question 29

What is the purpose of the Chordae Tendinae and papillary muscle?

Answer 29

The Chordae Tendinae is the tendon preventing the valves (tricuspid and mitral) from inverting), the papillary muscle is contracting when the heart contracts as the heart gets smaller to ensure that the chordae tendinae are prevented from inverting even on contraction of the heart.

Question 30

What is standard stroke volume?

Answer 30

75ml/beat

Question 31

What is standard CO?

Answer 31

5L/min

Question 32

Where in the body shows Alpha 1 receptors/B2 receptors for sympathetic innervation?

Answer 32

Every artery has alpha 1 receptors (causing arteriolar constriction) , but the cardiac and skeletal muscle also have many more Beta 2 receptors which swamp the response to constrict by their repsons to dilate

Question 33

In the injury response, what does it depend upon?

Answer 33

The injury response depends on action potentials invading the terminals of nociceptive C-fibres and triggering the release of substance P - which causes arteriolar dilation.

Question 34

What contributes to the pace maker potential?

Answer 34

Gradual closing of the leaky K+ channels and opening of the “funny” Na+ channels and T-type Ca2+ channels.