The total area of the surface of an object.

The relationship between the surface area and the volume of a shape.

The net movement of particles from an area of higher concentration to an area of lower concentration.

A specialised surface which enables the efficient exchange of substances.

The importance of exchange surfaces and transport systems in humans

Biology

The human circulatory system

The human heart and double circulatory system

Human blood cells and blood vessels

Microscopy of human blood cells and blood vessels

Moving into and out of the blood: diffusion, osmosis and active transport

Diffusion and surface area to volume ratio

Pupils will learn how the components of the human nervous system enable us to respond to changes outside and inside our bodies.

Pupils learned about biological molecules that are essential to life, including sugars and other carbohydrates, proteins and lipids, and the role of enzymes in catalysing the chemical reactions in which these substances are used and made.

This unit covers the human circulatory system, its link to the gas exchange system, and the adaptations of the heart, blood vessels, and blood components. It explains transport mechanisms like diffusion, osmosis, and active transport, and the need for exchange surfaces in multicellular organisms.

Transport and exchange surfaces in humans

which substances can diffuse in and out of a cell

Which factors does the surface area and volume affect?

True or false? Large living organisms have a large surface area to volume ratio.

Decreasing SA : V decreases diffusion rate.

Decreasing SA : V increases diffusion rate.

Why is a small surface area a disadvantage to organisms?

Having many villi {{}} the surface area over which diffusion can take place.

It means substances don't have to diffuse.

It moves nutrients and waste products around the body.

It reduces the time taken for substances to diffuse from the blood to the cells.

It brings blood near to the surface of cells which reduces diffusion distance.

It means active transport will occur instead of diffusion.

What are the advantages of a circulatory system?

How are the alveoli adapted for efficient diffusion?

The role of the circulatory system is to deliver {{}} and nutrients to cells and take away waste products.

Where in the lungs does gas exchange take place?

Which of the following statements about diffusion are correct?

Where are nutrients absorbed into the bloodstream?

Which blood vessel is only one cell thick?

What is the surface area to volume ratio of this shape?

Starter Quiz

The role of the circulatory system is to deliver and nutrients to cells and take away waste products.