7.4 The Structure of The Heart

Question 1

Where is the heart situated?

Answer 1

It lies in the thoracic cavity behind the sternum.

Question 2

What are the four min blood vessels in the heart?

Answer 2

Aorta, Pulmonary Vein, Pulmonary Artery, Vena Cava

Question 3

What is the function of the aorta and where is it?

Answer 3

It is connected to the left ventricle and carry oxygenated blood to all parts of the body except the lungs.

Question 4

What is the function of the vena cava and where is it?

Answer 4

It is connected to the right atrium and brings deoxygenated blood back fro the tissues of the body (except the lungs).

Question 5

What is the function of the pulmonary artery and where is it?

Answer 5

It is connected to the right ventricle and carries deoxygenated blood to the lungs, where its oxygen is replenished and its carbon dioxide is removed. It is the only artery that carries deoxygenated blood.

Question 6

What is the function of the pulmonary vein and where is it?

Answer 6

It is connected to the left atrium and brings oxygenated blood back from the lungs. It is the only vein that carries oxygenated blood.

Question 7

Which side of the heart is the oxygenated blood supposed to be at?

Answer 7

Left Side

Question 8

Which side of the heart is the deoxygenated blood supposed to be at?

Answer 8

Right Side

Question 9

Why does a mammalian’s heart have to be a double pump instead of a single pump?

Answer 9

In order to increase the pressure of the oxygenated blood before it is distributed to the rest of the body.

Question 10

What are the three types of valves in the heart?

Answer 10

Bicuspid valve (LEFT AV Valve) Tricuspid valve (RIGHT AV valve) Semi-Lunar valves

Question 11

What is the function of the Bicuspid valve and where is it found?

Answer 11

It is found between the left ventricle and the left atrium and prevents backflow of blood from the left ventricle to the left atrium.

Question 12

What is the function of the Tricuspid valve and where is it found?

Answer 12

It is found between the right ventricle and the right atrium and prevents backflow of blood from the right ventricle to the right atrium.

Question 13

What is the function of the Semi-Lunar valves and where are they found?

Answer 13

They are found in the aorta and pulmonary artery. They prevent backflow of blood into the ventricles.

Question 14

How is the heart supplied with oxygen?

Answer 14

The heart muscle is supplied by its own blood vessels called coronary arteries, hitch branch off the aorta shortly after it leaves the heart.

Question 15

What would happen if these coronary arteries become blocked?

Answer 15

The blockage would lead to a myocardial infarction because an area of the heart muscle is deprive of blood and oxygen therefore the muscle cells in this region are unable to respire (aerobically) and so die.

Question 16

Why is it important for oxygenated blood and deoxygenated blood to not mix?

Answer 16

A mixing of the blood would result in only a partially oxygenated blood reaching the cells and tissues. Therefore there would not be enough oxygen supple so there would be a reduced rate of diffusion gradient at the lungs and thus limit that rate of oxygen uptake.

Question 17

Draw a flow map to illustrate the bloods journey as it travels from the pulmonary vein.

Answer 17

Lungs, Pulmonary vein, left atrium, bicuspid valve, left ventricle, semi-lunar valve, aorta, body, vena cava, right atrium, tricuspid valve, right ventricle, semi-lunar valve, pulmonary artery, lungs

Question 18

What are the names of the 4 chambers of the heart?

Answer 18

Left atrium, Left ventricle, Right atrium, Right ventricle

Question 19

Label this diagram of the heart:

Answer 19

Question 20

What are the risk factors associated with cardiovascular disease?

Answer 20

• Smoking
• High Blood Pressure
• Diet
• Blood cholesterol

Question 21

How does the carbon monoxide due to smoking increase the risk of developing a cardiovascular disease?

Answer 21

• Carbon monoxide combines easily with the haemoglobin in red blood cells to form carboxyhaemoglobin. It therefore reduces the oxygen-carrying capacity of the blood. To supply the equivalent quantity of oxygen to the tissues the heart works harder = can lead to raised blood pressure that increases the risk of coronary heart disease and strokes.Furthermore, the reduction in the oxygen-carrying capacity of the blood means that it may be insufficient to supply the heart muscle during exercise = chest pain (angina) or a myocardial infarction (heart attack).

Question 22

How does the nicotine in cigarettes increase the risk of developing a cardiovascular disease?

Answer 22

• Nicotine stimulates the production of the hormone adrenaline, which increases heart rate and raises blood pressure = greater risk of smokers suffering coronary heart disease or a stroke. Nictine also makes the platelets in the blood more ‘sticky’ = leads to a higher risk of thrombosis/strokes/myocardial infarction.

Question 23

How does high blood pressure increase the risk of heart disease?

Answer 23

• As there is already a higher pressure in the arteries, the heart must work harder to pump blood into them = more prone to failure.
• Higher blood pressure within the arteries means that they are more likely to develop an aneurysm (weakening of the wall) and burst, causing haemorrhage.
• To resist the higher pressure within them, the walls of the arteries tend to become thickened and may harden = restrict the flow of blood.

Question 24

What do High-Density Lipoproteins (HDLs) do?

Answer 24

Remove cholesterol from tissues and transport it to the liver for excretion.

They help protect arteries against heart disease.

Question 25

What do Low-Density Lipoproteins (LDLs) do?

Answer 25

Transport cholesterol from the liver to the tissues, including the artery walls, which they infiltrate, leading to the development of atheroma, which may lead to heart disease.

Question 26

What are the treatments for Cardiovasculars Disorders and how do they work?

Answer 26

• Beta Blockers - Decrease the activity of the heart by inhibiting beta receptors.
• Coronary Artery Bypass - A vein or artery from another part of the body is used to bypass the blocked artery.
• Artificial Pacemaker - An insulated wire with an electrode at the end is inserted into a vein in the shoulder and then guided into the right artery or vein. Pacemaker conatins a battery placed under the skin.
• Angioplasty - A tube made of plastic with a small balloon on the end is passed into the blocked coronary artery. The balloon is then inflated at the region of the blockage, pushing the plaque that is blocking the artery out of the way. The balloon and guide are then removed.

Question 27

Give 2 examples of coronary heart disease and briefly explain them.

Answer 27

• Cardiac Infarction - Flow of blood in the coronary arteries is interrupted -> heart muscle is partially/completely deprived of its supply of oxygen + other nutrients -> can’t function normally. A branch of a coronary artery is blocked so the area of heart muscle supplied by that branch dies.
• Angina - Artery is narrowed = blood flow is reduced.
• Atherosclerosis - Thickening of the artery walls due to the deposition of fat + cholesterol in the lining of the artery. The deposit is called an atheroma. Calcium salts and fibrous tissue also accumulate and lead to the formation of the of hard, uneven patches called plaques which cause a narrowing of the artery and interfere with the even flow of blood.
• Coronary Thrombosis - A blood clot (thrombus) in the coronary circulation which often forms when the surface of a plaque breaks away. The clot then blocks the lumen of the blood vessel. If the clot becomes dislodged and travels through the bloodstream it is called an embolus.
• Cardiac Arrest - Right coronary artery becomes blocked -> SAN affected -> heart rate slows down/heart stop beating.
• Arrhythmia - Irregular or abnormal heart beat.
• Complete Heart Block - Blockage affects AVN severely or associated with conducting tissues = atria and ventricles beat independently.