Cardiac Physiology (Physiology)

Question 1

Name the three components of the circulatory system.

Answer 1

-Heart
-Blood vessels
-Blood

Question 2

Where is the heart located?

Answer 2

In the thoracic cavity, between the sternum and vertebrae, the base of the heart lies towards the right of the sternum and the apex towards the left.

Question 3

Two upper chambers of the heart

Answer 3

Atria

Question 4

Two lower chambers of the heart

Answer 4

Ventricles

Question 5

Explain the circulation of blood, both the systemic circulation and pulmonary circulation

Answer 5

Deoxygenated blood enters the right atrium via the superior vena cava, the inferior vena cava and the coronary sinuses.
The right atrium contracts, allowing that to oxygenated blood to flow from the right atrium to the right ventricle.
Deoxygenated blood leaves, the right ventricle via the right and left pulmonary arteries in goes for pulmonary circulation.
In the lungs, gaseous exchange occurs, which provides the blood with oxygen.
Oxygenated blood then moves into the left atrium via the right and left pulmonary veins.
The left atrium contracts, allowing oxygenated blood to flow from the left atrium to the left ventricle.
The left ventricle contracts, allowing blood to flow into the aorta, where it goes for systemic circulation and provides oxygenated blood to all the organ systems.
Deoxygenated blood from the organ systems, then retain back to the heart .

Question 6

Why is the left myocardium thicker than the right myocardium?

Answer 6

The systemic circulation is under high pressure and high resistance, unlike the pulmonary circulation

Question 7

What is meant by pressure and resistance of the blood flow?

Answer 7

Pressure is the force exerted by pumped blood on a vessel wall while resistance is the opposition to blood flow.

Question 8

How do heart valves ensure that blood flows in one direction?

Answer 8

When the pressure is greater behind the valves, they open, but when the pressure is greater in front of the valves, they close in order to ensure one directional flow of blood.

Question 9

How does the heart ensure that the AV valves are tight?

Answer 9

The AV valves are encoured to the papillary muscles by the chordae tendineae

Question 10

What do you call the right AV valve?

Answer 10

Tricuspid valve

Question 11

What do you call the left AV valve?

Answer 11

Bicuspid valve

Question 12

What are the two semi lunar valves that we have?

Answer 12

The pulmonary valve and the aortic valve

Question 13

The layers of the heart wall

Answer 13

•External epicardium.
• Middle myocardium- layer of cardiac muscle tissue.
•Inner endocardium- layer of endothelium.

Question 14

What are the two specialised types of cardiac muscle cells?

Answer 14

Contractile and auto-rhythmic cells.

Question 15

What are the effects of the ANS on HR and conduction velocity of the heart(4)

Answer 15

Sympathetic NS- NA binds to beta 1 receptors in the SA node and causes positive inotropy, chronotropy as well as demotropy.

Parasympathetic- Ach binds to M2 receptors and causes decreased HR and conduction velocity in AV node.

Question 16

What causes the sympathetic NS to increase HR?

Answer 16

The increased influx of calcium ions.

Question 17

What causes the parasympathetic NS to decrease the HR?

Answer 17

Increased efflux of K and decreased influx of Ca.

Question 18

Name and explain 2 periods of the events of cardiac cycle.(8)

Answer 18

Systole (period of ventricular contraction)
•Has three phases:
-Isovolumetric contraction:-Period between the mitral valve closing and the aortic valve opening.
-Rapid ejection:- Period between the mitral valve opening and closing.
-Reduced ejection.

Diastole (period of ventricular relaxation)
•Has four phases:
-Isovolumetric relaxation:- Period between the aortic valve closing and the mitral valve opening.
-Rapid ventricular filling:- Period just after the mitral valve opens.
-Reduced ventricular filling:- Period before the mitral valve closes.
-Atrial systole

Question 19

What are the ff waves for:
A. A wave
B. C wave
C. V wave

Answer 19

A. Atrial contraction
B. Right ventricle contracting
C. Passive filling of the right atrium