Heart & circulation

Question 1

What are cardiovascular diseases?

Answer 1

Diseases of the heart and circulation

Question 2

What are the main forms of cardiovascular diseases?

Answer 2

• Coronary heart disease
• Stroke

Question 3

What is the function of the heart and circulation?

Answer 3

To move substances around the body

Question 4

How do unicellular organisms move substances around?

Answer 4

As distances are short, substances such as oxygen, carbon dioxide and digestive products move around the organism by diffusion

Question 5

What is diffusion?

Answer 5

The movement of molecules from a region of high concentration to a region of low concentration

Question 6

Why can’t multicellular organisms rely on diffusion?

Answer 6

They are too large for diffusion to move substances around their bodies quickly enough

Question 7

How do multicellular organisms move substances around?

Answer 7

They rely on a mass transport system to move substances efficiently over long distances by mass flow

Question 8

What does a circulatory system consist of?

Answer 8

Animals usually have blood to carry vital substances around their bodies and a heart to pump it

Question 9

How do open circulatory systems work?

Answer 9

Blood circulated in large open spaces. A simple heart pumps blood out into cavities surrounding the animals organs. Substances can diffuse between the blood and cells.

Question 10

How do closed circulatory systems work?

Answer 10

Blood is enclosed within tubes - blood vessels. This generates higher blood pressures as the blood is forced along fairly narrow channels. This means the blood travels faster and so the blood system is more efficient at delivering substances around the body.

Question 11

Where does the blood travel in a closed circulatory system?

Answer 11

• The blood leaves the heart under pressure and flows along arteries and then arterioles to capillaries
• The capillaries come into close contact with most of the cells in the body where substances are exchanged between blood and cells
• The blood then returns to the heart by means of benumbed and then veins

Question 12

What is the function of valves?

Answer 12

To ensure that blood flows only in one direction

Question 13

How does blood flow in single circulatory systems? (fish example)

Answer 13

• The heart pumps deoxygenated blood to the gills
• Gaseous exchange takes place in the gills; there is diffusion of CO2 from the blood into the water that surrounds the gills, and diffusion of oxygen from this water into the blood within gills
• The blood leaving the gills then flows round the rest of the body before eventually returning to the heart

Question 14

How many times does the blood flow through the heart in single circulatory systems?

Answer 14

Once for each complete circuit of the body

Question 15

How does blood flow in double circulatory systems?

Answer 15

• The right ventricle of the heart pumps deoxygenated blood to the lungs where it receives oxygen
• The oxygenated blood then returns to the heart to be pumped a second time (by the left ventricle) out to the rest of the body

Question 16

How many times does the blood flow through the heart in double circulatory systems?

Answer 16

Twice for each complete circuit of the body

Question 17

What does the heart do to the blood returning from the lungs?

Answer 17

Gives the blood an extra ‘boost’ that reduces the time it takes for the blood to circulate round the whole body

Question 18

What does the extra ‘boost’ allow birds and mammals to have?

Answer 18

To have a high metabolic rate, as oxygen and food substances required for metabolic processes can be delivered more rapidly to cells and meet the needs of the organism

Question 19

What is the transport medium in animals?

Answer 19

Blood

Question 20

What does plasma contain?

Answer 20

• Mainly water
• Digested food molecules (glucose)
• Oxygen
• Carbon dioxide
• Proteins
• Amino acids
• Salts
• Enzymes
• Hormones
• Antibodies
• Urea

Question 21

What cells are carried in blood?

Answer 21

• Red blood cells
• White blood cells
• Platelets

Question 22

What is the heart made of?

Answer 22

Cardiac muscle

Question 23

What is the function of the right side of the heart?

Answer 23

It receives deoxygenated blood from the body and pumps it to the lungs

Question 24

What is the function of the left side of the heart?

Answer 24

It receives oxygenated blood from the lungs and pumps it to the body

Question 25

Label a diagram of the heart

Question 26

What is the function of the arteries?

Answer 26

Carry blood from the heart to the rest of the body

Question 27

What is the function of the veins?

Answer 27

Take blood back to the heart

Question 28

What is the function of the capillaries?

Answer 28

Where metabolic exchange occurs - substances are exchanged between cells and capillaries

Question 29

What common features do arteries and veins have?

Answer 29

• Walls contain collagen • Elastic fibres • Smooth muscle cells in walls

Question 30

What does collagen do?

Answer 30

Makes them strong and durable

Question 31

What do elastic fibres do?

Answer 31

Allows them to stretch to accommodate high pressure and recoil to maintain pressure on blood

Question 32

What does the smooth muscle do?

Answer 32

Allows them to constrict and dilate

Question 33

How are arteries adapted to carry out their function?

Answer 33

• Thick smooth muscular walls: maintain high pressure without damage - contract/exert pressure • Folded endothelium: allows stretching to accommodate high pressure • Narrow lumen: maintains blood at high pressure • Smooth lining: reduces friction to blood flow

Question 34

How are veins adapted to carry out their function?

Answer 34

• Thinner walls: allows skeletal muscle movement and low heart pressure to draw blood towards heart • Valves: ensures blood continues to move towards the heart • Large lumen: blood flows back to the heart under low pressure

Question 35

How are capillaries adapted to carry out their function?

Answer 35

• One cell thick walls: reduces diffusion distance, higher rate of diffusion • Large network near all cells: increases surface area which allows a higher rate of diffusion • Narrow lumen: reduces diffusion distance between RBC and tissue cells

Question 36

Label diagrams of arteries, veins and capillaries

Question 37

What happens to the blood vessels during systole?

Answer 37

The heart contracts, blood is forced into arteries and their elastic walls stretch to accommodate the blood

Question 38

What happens to the blood vessels during diastole?

Answer 38

The heart relaxes, the elasticity of the artery walls causes them to recoil behind the blood, helping to push the blood forward and smoothing blood flow

Question 39

How is the heart muscle supplied with blood?

Answer 39

Through its own coronary circulation; two vessels called the coronary arteries, a network of capillaries and two coronary veins

Question 40

How does the heart work?

Answer 40

The chambers of the heart alternately contract (systole) and relax (diastole) in a rhythmic cycle. One complete sequence of filling and pumping blood is called a cardiac cycle.

Question 41

What happens to the heart during systole?

Answer 41

Cardiac muscle contracts and the heart pumps blood out through the aorta and pulmonary arteries

Question 42

What happens to the heart during diastole?

Answer 42

Cardiac muscle relaxes and the heart fills with blood

Question 43

What are the 3 phases of the cardiac cycle?

Answer 43

1. Atrial systole 2. Ventricular systole 3. Diastole

Question 44

What happens in the atrial systole phase?

Answer 44

Blood under low pressure flows into the left and right atria from the pulmonary veins and vena cava. As the atria fill, the increasing pressure of blood against the atrioventricular valves pushes them open and blood begins to leak into the ventricles. The atria walls contract forcing more blood into the ventricles.

Question 45

What happens in the ventricular systole phase?

Answer 45

The ventricles contract from the base of the heart upwards, increasing the pressure in the ventricles. The pressure forces open the semilunar valves and pushes blood up and out through the pulmonary arteries and aorta. The pressure of blood against the atrioventricular valves closes them and prevents blood flowing backwards into the atria.

Question 46

What happens in the cardiac diastole phase?

Answer 46

The atria and ventricles relax. Elastic recoil of the relaxing heart walls lowers pressure in the atria and ventricles. Blood under higher pressure in the pulmonary arteries and aorta is drawn back towards the ventricles, closing the semilunar valves and preventing further back flow into the ventricles. The coronary arteries fill during diastole. Low pressure in the atria helps draw blood into the heart from the veins.

Question 47

Describe the roles of arterioles and capillaries in blood flow.

Answer 47

They offer a greater total surface area than the arteries, resisting flow more, slowing the blood down and causing the blood pressure to fall