Exchange and Transport

What is an exchange surface?

A specialised area that is adapted to make it easier for exchanges to occur.

What is urea and what organ is it removed from the body by?

Urea is a poison produced by breaking down amino acids, and it’s removed by the kidneys.

What is carbon dioxide and what organ is it removed from the body by?

Carbon dioxide is a waste gas in aerobic respiration, and it’s removed by the lungs.

What two things are needed for aerobic respiration?

Oxygen and glucose.

What are dissolved food molecules needed for?

To produce new substances for the body.

What is diffusion?

The movement of particles from a high to low concentration gradient.

What are the surfaces where diffusion happens like?

They’re thin so the distance of diffusion is short, and they have a large surface area so there is more room for diffusion to occur.

What happens if a cell’s volume is too big?

It can’t fill up via diffusion fast enough.

What are alveoli?

Pocket-shaped structures that excrete carbon dioxide.

Why do alveoli have walls that are one cell thick?

So the rate of diffusion can be increased.

What are the smallest blood vessels in the body?

Capillaries.

What are arteries?

The blood vessels that carry blood away from the heart.

What is an erythrocyte?

A red blood cell, therefore it carries oxygen.

What is the formula for aerobic respiration?

oxygen + glucose —> carbon dioxide + water

What is in the blood that enters the capillaries?

It has low oxygen and high carbon dioxide levels.

What is in the blood that exits the capillaries and why has it changed?

It has high oxygen and low carbon dioxide levels, because carbon dioxide has diffused out and oxygen has diffused in.

What is the word equation for aerobic respiration?

oxygen + glucose —> carbon dioxide + water

Which organ removes carbon dioxide from the body?

Lungs.

How is the SA:V ratio of the lungs increased?

They are rolled up many times and compacted into the chest cavity.

Why is the SA:V ratio of the lungs increased?

So more of a substance can fit into it at once, and faster.

When is urea formed?

During the breakdown of amino acids.

What waste substance do kidneys remove from the blood?

Urea.

Where do capillaries carry blood?

From arteries to veins.

What is the structure of the capillaries?

A narrow tube with a wall one cell thick.

Why do capillaries have thin walls?

To increase the rate of diffusion and shorten the diffusion distance.

Where do veins carry blood?

To the heart.

What is the structure of the veins?

A wide tube with a thin, flexible wall.

What is the name of the system that circulates blood?

The circulatory system.

Why do veins have thin walls?

Because blood flows under low pressure.

Why do veins have valves?

They ensure that blood only flows in the right direction.

Where do the arteries carry blood?

Away from the heart.

What is the structure of the arteries?

A narrow tube with a layer of elastic and muscle fibres.

Why do arteries have thick walls?

So they can withstand high pressure.

Why are arteries elastic?

To even out blood pressure and allow the body to cope.

What are valves?

They prevent blood from flowing the wrong way.

Approximately how many litres of blood are in the human body?

5.

What is plasma?

Straw-coloured liquid in which all cells are suspended.

What does plasma carry?

Dissolved substances such as glucose, carbon dioxide and urea.

What are red blood cells/erythrocytes?

Biconcave cells that contain haemoglobin and carry oxygen around the body.

How are red blood cells adapted to their job?

• Haemoglobin absorbs oxygen.

• The cells have high surface area due to the biconcave shape.

• There is no nucleus so more room for oxygen to be absorbed.

What is the function of white blood cells?

To destroy cancers and fight pathogens by destroying cells that have gone wrong.

What are platelets?

Disk-shaped cell fragments that assist in clotting blood.

What are the two types of white blood cell?

Phagocytes and lymphocytes.

What do lymphocytes do?

They produce proteins called antibodies that stick to and destroy foreign cells.

What do phagocytes do?

They surround foreign cells and digest them.

What do skeletal muscles do in the circulatory system?

They help to push blood along the leg veins.

What is a heart attack caused by?

Blood not being able to reach the heart.

What is the heart made of?

Cardiac muscle.

What does the heart need a constant supply of?

Oxygen and glucose (aerobic respiration).

What is the order of blood transfer?

• Body

• Vena cava

• Right atrium

• Right ventricle

• Pulmonary artery

• Lungs

• Pulmonary vein

• Left atrium

• Left ventricle

• Aorta

• Body

What is the formula for cardiac output?

Cardiac output = stroke volume x heart rate

Why does the heart rate increase during exercise?

Because more oxygen is needed for respiration.

Exothermic

When energy is released into the surroundings by a chemical reaction.

Mitochondria

The organelle where aerobic respiration takes place.

When is anaerobic respiration used?

When oxygen is being used faster than it’s being replaced.

What is the equation for anaerobic respiration?

glucose —> lactic acid