Cardiovascular System

Question 1

Which two ‘loops’ of the circulatory system exist?

Answer 1

Pulmonary circuit

Systemic circuit

Question 2

What is meant by a closed cardiovascular system?

Answer 2

Blood never leaves vessels

Question 3

The average adult has how much how much circulating blood? What does this consist of?

Answer 3

5 litres

3 litres of plasma
2 litres of red blood cells

Question 4

Where does most of our blood lie in our blood vessels at any one time?

Answer 4

In peripheral veins (65%)

Question 5

What is the valve between the right atrium and right ventricle called?

Answer 5

Tricuspid valve

Question 6

What is the valve between the left atrium and left ventricle called? How many cusps does this have?

Answer 6

Mitral valve

2

Question 7

What is the valve between the pulmonary artery and the right ventricle called?

Answer 7

Pulmonic valve

Question 8

What is the valve between the aorta and left ventricle called?

Answer 8

Aortic valve

Question 9

Why are the structures of the right side of the heart generally more fragile?

Answer 9

Deals with blood which is at lower pressures

Question 10

What are the two main arteries supplying the heart? Where do they stem from?

Answer 10

Left and right coronary arteries

Stem from the aorta

Question 11

What are end arteries? What occurs in blockage of end arteries?

Answer 11

Terminal artery supplying all or most of the blood to a part of the body

So blockage —> insufficient blood supply to tissue

Question 12

Give two examples of end arteries? What is the only example of an absolute end artery in the body?

Answer 12

Coronary arteries
Cerebral arteries

Central artery to the retina

Question 13

What is stenosis?

Answer 13

Narrowing of an artery

Question 14

What is meant by collateral circulation?

Answer 14

More than 1 artery supplies blood to a particular part of the body

Question 15

What happens at the SA node?

Answer 15

Wave of excitation results in atrial systole

Question 16

What happens at the AV node?

Answer 16

Wave of excitation down the left and right bundle branches to the Purkinje fibres —-> ventricular systole

Question 17

Why is the wave of excitation paused at the AV node?

Answer 17

To avoid simultaneous contraction, allows all the blood to enter the ventricle

Question 18

The elasticity of arteries allows them to respond to changes in blood _____ to keep blood flowing

Answer 18

Pressure

Question 19

What is the systolic pressure?

Answer 19

Typically 120mmHg - the blood pressure in the aorta during systole

Question 20

What is the diastolic pressure?

Answer 20

Typically 70-80mmHg

Question 21

What are the 3 layers present in the walls of most blood vessels?

Answer 21

Tunica Intima - endothelium next to lumen
Tunica Media
Tunic Adventitia

Question 22

What is the difference between the tunic media found in arteries and veins?

Answer 22

Much thicker in arteries

Question 23

What is an aneurysm?

Answer 23

Dilation of a blood vessel

Question 24

What is the tunica adventitia?

Answer 24

A thin layer of fibroelastic connective tissue on the outer layer of blood vessels

Question 25

What is the thickness of the tunic media in arteries? How are the smooth muscle cells in this layer connected?

Answer 25

40 layers of smooth muscle By gap junctions

Question 26

What are arterioles? What is the structure of its tunica media?

Answer 26

Arteries with a diameter of less than 0.1mm Only 1-3 layers of smooth muscle in the tunica media

Question 27

What is the wall structure of capillaries?

Answer 27

A single layer of endothelium and a basement membrane

Question 28

Is there a high or low blood velocity through capillaries? Why?

Answer 28

Low - around 0.3 mm/s | Allows gas/nutrient exchange to take place

Question 29

Where are pericytes found?

Answer 29

In capillaries and venules - form a branching network on outer surface of endothelium

Question 30

What is the structure of the wall of postcapillary venules?

Answer 30

Same as capillaries (endothelium + pericytes)

Question 31

What is the wall structure of venules?

Answer 31

Endothelium + pericytes OR thin smooth muscle cells

Question 32

What do veins and venules contain to prevent the back flow of blood?

Answer 32

Valves

Question 33

What is the largest diameter blood vessel?

Answer 33

Veins

Question 34

What is the structure of the wall of a vein?

Answer 34

More connective tissue Less muscle fibres Tunica media = 2-3 smooth muscle cell layers

Question 35

What is the meaning of capacitance vessels?

Answer 35

Can stretch to hold more blood (or recoil to hold less) with no pressure changes

Question 36

Blood flows in which order through vessels starting with muscular arteries?

Answer 36

``` Muscular arteries Arterioles (Precapillary sphincters) Capillaries Post capillary venules Venules Veins ```

Question 37

How does blood flow in veins? (2)

Answer 37

With the help of contraction of skeletal muscle Thoracic pump when breathing

Question 38

What is the major vein of the heart?

Answer 38

Coronary sinus

Question 39

What does failure of the calf muscle pump result in?

Answer 39

Venous hypertension ----> venous ulceration