Organisation: the circulatory system

Question 1

What is the role of the circulatory system?

Answer 1

transport oxygen and nutrients to the body’s tissues

Question 2

What are the top chambers of the heart known as?

Answer 2

atria

Question 3

What are the bottom chambers of the heart known as?

Answer 3

ventricles

Question 4

What can be found between the chambers and the vessels? What is their function?

Answer 4

• valves
• prevent blood flowing backwards

Question 5

Describe the route of oxygenated blood through the circulatory system.

Answer 5

1. Blood enters heart via the pulmonary vein.
2. Blood enters into left atrium.
3. The heart contracts and blood enters into the left ventricle.
4. Blood leaves the heart via the aorta which takes it to the rest of the body.

Question 6

Describe the route of deoxygenated blood through the circulatory system.

Answer 6

1. Blood enters heart via the vena cava.
2. Blood enters into right atrium.
3. The heart contracts and blood enters into the right ventricle
4. Blood leaves the heart via the pulmonary artery which takes it to the lungs.

Question 7

On which sides of the heart are oxygenated and deoxygenated blood pumped respectively.

Answer 7

Oxygenated - left
Deoxygenated - right

Question 8

What are pacemaker cells?

Answer 8

A group of cells in the right atrium that produce small electrical impulses which spread through the muscular walls of the heart causing them to contract.

Question 9

What is the benefit of humans having a double circulatory system?

Answer 9

It makes the circulatory system more efficient.
For example, oxygenated blood can be pumped around the body at a higher pressure by the left ventricle

Question 10

What are cardiovascular diseases? What is a key feature of them?

Answer 10

Cardiovascular diseases are diseases of the heart and blood vessels.

They are non-communicable.

Question 11

What are coronary arteries? What is their function?

Answer 11

Arteries that branch out of the aorta and spread out into the heart muscle.

Their purpose is to supply oxygen to the muscle cells of the heart allowing them to respire and release energy needed for contraction.

Question 12

What is coronary heart disease?

Answer 12

Where layers of fatty material build up inside the coronary arteries

Question 13

What are the effects of coronary heart disease?

Answer 13

The fatty substances narrow the artery.
This reduces the flow of blood through the coronary arteries.
This results in a lack of oxygen for the heart muscle.
This can result in a heart attack.

Question 14

What are the two common treatments for coronary heart disease?

Answer 14

• statins
• stents

Question 15

What are statins? How do they work to treat coronary heart disease.

Answer 15

Statins are drugs which reduces the level of cholesterol in the blood.
This slows down the rate that fatty material builds up in the arteries.

Question 16

What are the advantages and disadvantages of statins?

Answer 16

Advantages
- proven to reduce the risk of coronary heart disease

Disadvantages
- have unwanted side effects

Question 17

What is a stent? How does it work to treat coronary heart disease?

Answer 17

A tube which is inserted into the coronary artery to keep it open.
This allows the blood to flow normally through the artery.

Question 18

What are the advantages and disadvantages of stents?

Answer 18

Advantages
- allow blood to flow normally through the artery

Disadvantages
- will not prevent other regions of the coronary arteries from narrowing
- doesn’t treat the underlying causes of the disease

Question 19

What factors make someone at a higher risk of having a heart attack?

Answer 19

• high cholesterol (more likely to get a blockage in coronary artery)
• older people
• smoking
• genetics

Question 20

Capillaries
- function
- adaptations

Answer 20

Function
- branch off from arteries
- carry blood close to cells in order to exchange substances with them
- supply cells with nutrients and oxygen and take away waste such as CO₂

Adaptations
- permeable walls: allow substances to diffuse in and out
- walls only one cell thick - short diffusion pathway, increases rate of diffusion
- narrow lumen - blood moves slowly giving more time for diffusion

Question 21

Veins
- function
- adaptations

Answer 21

Function
- take the blood from capillaries back to the heart

Adaptations
- thinner walls -blood is at a lower pressure
- wide lumen - enables low pressure
- valves - keep blood flowing in the right direction

Question 22

Arteries
- function
- adaptations

Answer 22

Function
- carry high pressure blood
- from the heart to the organs in the body

Adaptations
- thick muscular walls: adds strength allowing them to resist high pressure
- thick eleastic layer: allows arteries to stretch and recoil in orderto withstand high pressure

Question 23

What is the approximate value of the natural resting heart rate?

Answer 23

70bpm

Question 24

How does the doubles circulatory system work?

Answer 24

• one pathway carries blood from the heart to the lungs
• one pathways carries blood from the heart to the tissues

Question 25

Where does blood pumped by the right ventricle go?

Answer 25

the lungs

Question 26

Where does blood pumped by the left ventricle go?

Answer 26

body tissues

Question 27

Why is the double circulatory system important?

Answer 27

It makes the circulatory system more efficient. For example oxygenated blood can be pumped around the body at a higher pressure by the left ventricle.

Question 28

Why would having only one ventricle make the circulatory system less efficient than having two ventricles?

Answer 28

Oxygenated and deoxygenated blood mixes so less oxygen reaches body cells.

Question 29

Where can pacemaker cells be found?

Answer 29

right atrium