Multicellular organisms need transport systems to deal with surface area to volume ratio issue. Animal transport and exchange systems In mammals, nutrients, oxygen and carbon dioxide are transported in the blood.

Pathway of blood through heart, lungs and body.

Heart structure to include right and left atria and ventricles.

Blood vessels to include: aorta, vena cava, pulmonary arteries and veins, and coronary arteries.

Arteries have thick, muscular walls, a narrow central channel and carry blood under high pressure.

Veins carry blood under low pressure; have thinner walls and a wide channel.

Veins contain valves to prevent backflow of blood.

Capillaries form networks at organs and tissues, and are thin walled and have a large surface area, allowing exchange of materials.

Red blood cells contain haemoglobin and are specialised to carry oxygen

Heart – syllabus content

Structure of the heart

Right atrium

Chambers of the heart

Right ventricle

Left atrium

Left ventricle

Heart structure to include right and left atria and ventricles.

Note: The left ventricle has a thicker wall (more muscle in its wall) than the right ventricle because it pumps blood further

Blood vessels entering and leaving the heart

Vena cava

Blood coming from the body

Pulmonary artery Blood to the lungs

Pulmonary vein

Blood from the lungs

Aorta

Blood to the body

X X

X x

Position of heart valves

Blood vessels to include: aorta, vena cava, pulmonary arteries and veins, and coronary arteries.

The heart tissue receives blood from the coronary arteries

Right coronary

artery

Left coronary

artery

Blood supply to the heart itself

Arteries have thick, muscular walls, a narrow central channel and carry blood under high pressure.Veins carry blood under low pressure; have thinner walls and a wide channel. Veins contain valves to prevent backflow of blood.

Arteries Veins

Take blood away from the heart Take blood back to the heart

Have thick muscular walls and a narrow lumen - blood is under high

pressure

Have thin walls and a wide lumen - blood is at low pressure

Have valves to prevent backflow of bloodNo valves

Artery structureThick layer containing smooth muscle

Narrow channel

Vein structure

Thin layer containing smooth muscle

Wide channel

Capillaries

Capillaries are very small, thin walled vessels that are found close to all body cells

Substances are exchanged between the blood and cells through the capillary walls

Capillaries form networks at organs and tissues, and are thin walled and have a large surface area, allowing exchange of materials.

Capillary beds

Body cells are found close to capillaries in capillary beds

Substances like glucose and oxygen pass by diffusion from the blood in the capillaries to the liquid around the cells then into the cells.

Carbon dioxide diffuses in the other direction

capillary

Tissue fluid

Body cells

Glucose and oxygen

Carbon dioxide

Capillaries have a large surface area and thin walls to allow efficient exchange of substances

Oxygen is transported in red blood cells

Red blood cells contain a substance called haemoglobin.

When the oxygen concentration is high (in the lung capillaries), haemoglobin joins with oxygen to make oxyhaemoglobin

Oxygen is carried in the blood joined to haemoglobin

When the oxygen concentration is low (in the body capillaries) oxyhaemoglobin breaks down again to release the oxygen for the body cells.

in lung capillaries in body capillaries

Haemoglobin + oxygen oxyhaemoglobin

Red blood cells contain haemoglobin and are specialised to carry oxygen