IGCSE Blood and Circulation

What is a double circulatory system?

Blood passes through the heart twice in one complete circuit

What is pulmonary circulation?

Blood flow between heart and lungs

What is systemic circulation?

Blood flow between heart and body

What is the function of blood?

Transport substances, defence, clotting, heat distribution

What is plasma?

Liquid part of blood that carries dissolved substances

What does plasma carry?

Glucose, amino acids, CO2, urea, hormones, heat

What is the function of red blood cells?

Carry oxygen

What is haemoglobin?

Protein that binds oxygen in red blood cells

What is oxyhaemoglobin?

Haemoglobin combined with oxygen

How are red blood cells adapted?

No nucleus, biconcave shape, contain haemoglobin, flexible

What is the function of white blood cells?

Defend against pathogens

What are phagocytes?

White blood cells that engulf pathogens

What are lymphocytes?

White blood cells that produce antibodies

What are antibodies?

Proteins that target specific pathogens

What are memory cells?

Cells that allow faster response to future infections

What is the function of platelets?

Help blood clotting

What happens in blood clotting?

Platelets release chemicals, fibrin forms mesh, clot forms

Why do we need blood clots?

To prevent blood loss and pathogen entry

What are the types of blood vessels?

Arteries, veins, capillaries

What do arteries do?

Carry blood away from the heart at high pressure

What are features of arteries?

Thick walls, narrow lumen, high pressure, no valves

What do veins do?

Carry blood to the heart

How are Veins Adapted to their Function

Thin walls, wide lumen, low pressure, valves present

What is the function of valves in veins?

Prevent backflow of blood

What do capillaries do?

Exchange of substances between blood and tissues

What are capillaries adapted for?

Thin walls, large surface area, slow blood flow

What are the chambers of the heart?

Right atrium, right ventricle, left atrium, left ventricle

What do atria do?

Receive blood

What do ventricles do?

Pump blood out of the heart

Why is the left ventricle thicker?

Pumps blood around the whole body at high pressure

What is the role of heart valves?

Prevent backflow of blood

What is the path of blood through the heart?

Body → vena cava → right atrium → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → aorta → body

What does the pulmonary artery do?

Carries deoxygenated blood to lungs

What does the pulmonary vein do?

Carries oxygenated blood from the lungs to the left atrium of the heart

What does the aorta do?

Carries oxygenated blood to body

What is coronary circulation?

Blood supply to heart muscle

What happens if coronary arteries are blocked?

Heart attack due to lack of oxygen

Why are capillary walls thin?

To allow fast diffusion

What is diffusion in capillaries?

Movement of substances from high to low concentration

Why are red blood cells biconcave?

Increases surface area for oxygen absorption

What is the role of the septum?

Separates oxygenated and deoxygenated blood

What is tissue fluid?

Fluid surrounding cells formed from plasma

How is tissue fluid formed?

High pressure pushes plasma out of capillaries

What is lymph?

Excess tissue fluid drained into lymphatic system

What is the function of the circulatory system in respiration?

Supplies oxygen and glucose, removes carbon dioxide

What is oxygen transport in blood?

Oxygen binds to haemoglobin forming oxyhaemoglobin

What is the difference between arteries and veins?

Arteries carry blood away under high pressure

What is the role of the heart?

Pumps blood around the body

What is systole?

Heart contraction phase

What is diastole?

Heart relaxation phase