Cardiovascular System Overview

Question 1

What are the functions of the cardiovascular system?

Answer 1

To transport nutrients, oxygen and waste products around the body
To transfer heat - generally from core to skin
Buffer body pH
Transport hormones
Assist in response to infection
Assist in urine formation

Question 2

The pulmonary artery splits in two so that one artery travels to the left lung and the other to the right. T/F?

Answer 2

True

Question 3

In most people, how many pulmonary veins are there?

Answer 3

Four

Question 4

The valves of the heart open and close simultaneously in response to what kind of gradient?

Answer 4

Pressure gradient

Question 5

What is the name of the ‘heart strings’ which help to orientate the heart valves?

Answer 5

Chordae tendinea

Question 6

When listening to the heart with a stethoscope two heart sounds should be heard. What do these sounds represent?

Answer 6

The first is the AV valves closing, the second is the semilunar valves closing.

Question 7

What are the two elements if the cardiac cycle called?

Answer 7

Systole - contraction

Diastole - realaxation

Question 8

What is the end systolic volume?

Answer 8

The left over blood in the heart following a heart contraction as not all the blood volume is pumped out

Question 9

What is the stroke volume of the heart?

Answer 9

The volume of blood ejected from the heart per beat

Question 10

What are the names of the two nodes of the heart involved in contraction?

Answer 10

Sinoatrial node

Atrioventricular node

Question 11

What does the P wave of an electrocardiogram show?

Answer 11

Atrial depolarisation

Question 12

What does the QRS complex of an electrocardiogram show?

Answer 12

Ventricular depolarisation

Question 13

What does the T part of an electrocardiagram show?

Answer 13

Ventricular repolarisation

Question 14

Why is atrial repolarisation not seen on an ECG?

Answer 14

Because it is masked by the QRS complex

Question 15

The delay through the AV node in the contraction of the heart is represented by what phase of an ECG?

Answer 15

The P R interval

Question 16

The plateau phase of heart contraction is shown on am ECG as what phase?

Answer 16

The S T interval

Question 17

In phase three of an action potential in the SA node, how does repolarisation occur?

Answer 17

By the outward movement of potassium

Question 18

What occurs during phase four of an action potential in the SA node?

Answer 18

Calcium ions move inwards and potassium ions move outwards causing a very gradual depolarisation until a threshold is met and an action potential fired.

Question 19

What is the main adrenoceptor that exists on nodal tissue in the heart?

Answer 19

Beta one receptors

Question 20

The right vagus nerve terminates on the SA node and the left vagus nerve terminates on the AV node. T/F?

Answer 20

True

Question 21

What effect will increased volume of blood in the heart have on the heart muscle?

Answer 21

The strength of heart muscle contractions will increase

Question 22

The action potential for a Purkinji fibre is similar to that of a neuron. T/F?

Answer 22

True

Question 23

Which node acts as the main pacemaker of the heart?

Answer 23

The SA node

Question 24

Because of the SA node the heart does not require innervation to initiate an action potential. Why is it, then, that it does recieve innervation?

Answer 24

The nerves to the heart control are not necessary for contraction to occur but they control pace at which it contracts

Question 25

Describe the events of mid to late diastole.

Answer 25

The atria and ventricle are both relaxed but atrial pressure is higher than ventricular pressure because the atria are filling with blood so the AV valves are open and blood flows from the atria into the ventricle. The semilunar valves are closed. Ventricular pressure slowly increases as it fills with blood. Towards the end of diastole the SA node discharges and the atria contract to force the remaining volume of blood into the ventricle

Question 26

Describe the events of systole.

Answer 26

From the AV node the wave of depolarisation passes over the ventricular tissue and the ventricles contract. This increases ventricle pressure so that the AV valves close. Once the pressure in the ventricle increases enough the semilunar valves will open and blood is forced from the ventricles into the arteries. Blood is ejected rapidly at first, then more slowly towards the end of systole. As blood flows into the arteries, there pressure increases to a point where it is greater than ventricular pressure and the semilunar valves close.

Question 27

Describe the events of early diastole.

Answer 27

The semilunar valves close because arterial pressure is increasing and ventricular pressure is decreasing as the ventricles relax. The AV valve also remains closed because ventricular pressure is still higher than atrial pressure. Once the ventricles have relaxed further atrial pressure will be greater than ventricular pressure so the AV valves open allowing blood to fill the heart again

Question 28

What is the clinical relevance of diastolic pressure?

Answer 28

It is during diastole that the myocardium itself is supplied with oxygenated blood through the coronary arteries - this is different from all other tissues which receive blood during systole

Question 29

Diseases or inherited conditions causing a fault in The electrical conduction system of the heart will result in what symptoms?

Answer 29

Lightheadedness
Palpitations
Syncope
Cardiac arrest