2.8.10 The Heart

Question 1

The heart organ is a double, what?

Answer 1

Double Pump

Question 2

Where does Oxygenated blood from the lungs enter

Answer 2

the left side of the heart and is pumped to the rest of the body (the systemic circuit)

Question 3

Why does the left ventricle have a thicker muscle wall than the right ventricle

Answer 3

it has to pump blood at high pressure around the entire body,

Question 4

Where does Deoxygenated blood from the body enter

Answer 4

enters the right side of the heart and is pumped to the lungs (the pulmonary circuit)

• The right ventricle is pumping blood at lower pressure to the lungs

Question 5

What does the septum do?

Answer 5

A muscle wall called the septum separates the two sides of the heart

Question 6

Where is blood pumped

Answer 6

Blood is pumped towards the heart in veins and away from the heart in arteries

Question 7

The coronary arteries supply, what?

Answer 7

the cardiac muscle tissue of the heart with oxygenated blood

Question 8

As the heart is a muscle it needs a constant supply, of what?

Answer 8

oxygen (and glucose) for aerobic respiration to release energy to allow continued muscle contraction

Question 9

Where does Deoxygenated blood coming from the body flow

Answer 9

through the vena cava and into the right atrium

Question 10

The atrium contracts and the blood is forced through, what?

Answer 10

through the tricuspid (atrioventricular) valve into the right ventricle

Question 11

The ventricle contracts and the blood is pushed through the, what?

Answer 11

semilunar valve into the pulmonary artery

Question 12

The blood travels to the lungs and moves through the capillaries past the alveoli where, what takes place?

Answer 12

gas exchange takes place

• Low pressure blood flow on this side of the heart prevents damage to the capillaries in the lungs

Question 13

Oxygenated blood returns via, what?

Answer 13

the pulmonary vein to the left atrium

Question 14

The atrium contracts and forces the blood through the, what?

Answer 14

bicuspid (atrioventricular) valve into the left ventricle

Question 15

The ventricle contracts and the blood is forced through the, what?

Answer 15

the semilunar valve and out through the aorta

Question 16

Exam Tip

Answer 16

Remember : Arteries carry blood Away from the heart

When explaining the route through the heart we usually describe it as one continuous pathway with only one atrium or ventricle being discussed at a time, but remember that in reality, both atria contract at the same time and both ventricles contract at the same time

Also, the heart is labelled as if it was in the chest so the left side of a diagram is actually the right hand side and vice versa

Question 17

Describe the pathway of blood through the heart

Answer 17

1. Deoxygenated blood coming from the body flows through the vena cava and into the right atrium

Question 18

How is a heart rate measured

Answer 18

by counting the number of times a heart beats in a minute (bpm)

Question 19

The natural resting heart rate is controlled by a group of cells located in the right atrium called the, what?

Answer 19

pacemaker

Question 20

What is the role of the pacemaker

Answer 20

The role of the pacemaker is to coordinate the contraction of the heart muscle and regulate the heart rate

Question 21

Pacemaker cells send out, what?

Answer 21

electrical impulses which initiate a contraction in the cardiac muscle

Question 22

Other factors can also influence the heart rate, such as the hormone, called?

Answer 22

adrenaline

Question 23

The heart pumps blood around the body in order to supply respiring cells with what?

Answer 23

oxygen and glucose

Question 24

The blood also removes, what? from respiring cells

Answer 24

waste products

Question 25

During exercise, the cells of the muscles respire more rapidly in order to provide energy for, what?

Answer 25

muscle contraction

Question 26

If exercise is moderate respiration may be, what?

Answer 26

aerobic

Question 27

If exercise is intense respiration may be, what?

Answer 27

anaerobic

Question 28

An increase in respiration means an increase in requirement for oxygen and glucose as well as an increase in production of, what?

Answer 28

waste products that need to be removed

Question 29

The nervous system responds to this requirement by stimulating the following changes:

Answer 29

1. Heart rate increases to deliver oxygen and glucose and remove waste more frequently

Question 30

Production of the hormone adrenaline increases the heart rate as part of a response called, what?

Answer 30

fight or flight’ response

Question 31

At the end of a period of exercise, the heart rate may remain high for a period of time why is that?

Answer 31

as oxygen is required in the muscles to break down the lactic acid from anaerobic respiration

• This is how the oxygen debt is paid off

Question 32

The time taken for the heart rate to return to the resting rate is called, what?

Answer 32

recovery time

• A physically fit person will have a lower resting heart rate and a shorter recovery time compared to an unfit person

Question 33

Like all cells in the body, cardiac muscle cells need a supply of blood to, do what?

Answer 33

deliver oxygen and glucose and to remove waste products such as carbon dioxide

Question 34

The blood is supplied to the heart by the, what?

Answer 34

coronary arteries which branch off directly from the aorta

• The heart needs to constantly respire, so it is vital that it receives oxygen

Question 35

The coronary arteries supply the heart with, what?

Answer 35

oxygenated blood

Question 36

In coronary heart disease (CHD), layers of fatty material (plaque) build up inside, what?

Answer 36

inside the coronary arteries

Question 37

These fatty deposits are mainly formed from what?

Answer 37

cholesterol

Question 38

There are two sources of in the body, what are they?

Answer 38

Dietary cholesterol (from animal products eaten)

Cholesterol synthesised by the liver

Question 39

If a coronary artery becomes partially or completely blocked by these fatty deposits, what does it lose

Answer 39

it loses its elasticity and cannot stretch to accommodate the blood which is being forced through every time the heart contracts

Question 40

The flow of blood through the arteries is reduced, resulting in what?

Answer 40

in a lack of oxygen for the heart muscle

• Partial blockage of the coronary arteries creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina
• Complete blockage means cells in that area of the heart will not be able to respire aerobically, leading to a heart attack

Question 41

Treatment of CHD involves, what?

Answer 41

increasing the width of the lumen of the coronary arteries using a stent, or prescribing statins to lower blood cholesterol

Question 42

There are several risk factors which will increase the chances of coronary heart disease, what are they?

Answer 42

Obesity

• Carrying extra weight puts a strain on the heart
• Increased weight can lead to diabetes which further damages your blood vessels

High blood pressure
- This increases the force of the blood against the artery walls and consequently leads to damage of the vessels

High cholesterol
- Speeds up the build up of fatty plaques in the arteries leading to blockages

Smoking
- Chemicals in smoke cause an increase in plaque build up and an increase in blood pressure

• Carbon monoxide also reduces the oxygen-carrying capacity of the red blood cells