IGCSE Chapter 05 Blood & Circulation

Define single circulatory system.

The blood is pumped from the heart to the gas exchange organ and then directly round the body.

Explain why heart rate increases during exercise.

To increase supply of oxygen to muscles.

For more aerobic respiration.

To release more energy for muscle contraction.

To take away CO₂ faster.

Name the blood vessel that transports blood to the heart muscle.

Coronary artery.

Name the cells in the body that produce antibodies.

Lymphocytes.

Name the pale yellow liquid that red and white blood cells are floating in.

Plasma.

Name the vessel through which blood enters the left side of the heart.

Pulmonary vein.

State four molecules that are transported in blood plasma.

Glucose.

Amino acids.

Fatty acids.

Hormones.

Antibodies.

Urea.

Carbon dioxide.

State three factors that can increase the risk of coronary heart disease.

High blood pressure.

Diet high in saturated fats.

Lack of exercise.

Smoking.

What are the consequences of coronary heart disease?

Coronary artery may become blocked by a fatty deposit.

Less oxygenated blood reaches heart muscle.

Less aerobic respiration takes place (more anaerobic respiration).

Heart muscle cells may die.

What happens to haemoglobin when in respiring muscle tissue?

It unloads oxygen to form haemoglobin.

What happens to haemoglobin when in the lungs?

It loads oxygen to form oxyhaemoglobin.

What happens to the heart muscle when it is in diastole?

It is relaxing.

What happens to the heart muscle when it is in systole?

It is contracting.

What is an antigen?

A chemical marker that antibodies recognise and bind to.

What is the function of muscle in the wall of an arteriole?

To constrict the arteriole, and reduce the amount of blood flowing through it.

What is the function of the septum?

It separates the two sides of the heart.

Preventing oxygenated and deoxygenated blood from mixing.

What is the name of the protein that forms blood clots?

Fibrin.

What is the role of a lymphocyte?

To recognise a specific antigen on a pathogen.

To produce antibodies that will bind to the antigen.

Pathogen is killed or clumped together by the antibodies.

What is the role of a phagocyte?

To engulf foreign particles / pathogens.

The pathogen is therefore killed.

Enzymes break down the pathogen.

Smaller molecules are then absorbed by the phagocyte.

Which hormone is responsible for the fight or flight response?

Adrenaline.

Which part of the brain controls heart rate?

Medulla.

Which type of lymphocytes provide immunity?

Memory cells.

Which valves are found at the opening of the aorta?

Semilunar valves.

Which valves separate the atria from the ventricles?

AV (atrioventricular) valves.

Which ventricle has the thicker wall?

Left ventricle.

Why are there valves in veins?

Because blood is flowing at low pressure, against gravity.

Why might some in a population not be vaccinated against a particular disease?

Concerns over side effects of immunisation / concerns over the risk of allergic reactions.

Medical reason for not being immunised.

Too young.

Scared of needles.

No access to healthcare.