Edexcel Biology GCSE - Gas Exchange in Animals Part 1

Tiny air sacs in the lungs, where gas is exchanged during breathing.

The plural of ‘bronchus’. The bronchi are the two major air tubes in the lungs.

The many small, branching tubules into which the bronchi subdivide.

Tiny blood vessels with walls one-cell thick where exchange of materials occurs.

A gaseous compound of carbon and oxygen, which is a by-product of respiration, and which is needed by plants for photosynthesis.

A strong, flexible type of connective tissue. It forms C-shaped rings in the trachea that keep the airway open.

The difference in the concentration of a chemical across a membrane.

Finger-like projections in the small intestine that provide a large surface area for the absorption of food.

Breathing in and out.

The windpipe, the tube that leads from the mouth towards the lungs.

The organ system where air is taken into and out the body, and gas exchange happens.

Thin, moist membranes surrounding the lungs that make an airtight seal.

Thin, moist membranes surrounding the lungs that make an airtight seal.

Gaseous element making up about 20% of the air, which is needed by living organisms for respiration.

Sets of muscles between the ribs which raise and lower the rib cage.

The ribs and upper backbone, and the organs found in the chest.

A large sheet of muscle that separates the lungs from the abdominal cavity.

A cell that forms part of an epithelium.

An area of the lungs that is adapted for efficient transfer of gasses.

will move in both directions, but there will be a net movement from high to low concentration will end up evenly spread throughout the liquid or gas, but will continue to move

Unicellular organisms, such as bacteria, have a very small surface area:volume ratio. Substances can diffuse in and out at a high rate and easily reach all parts of the cell.

Because of their smaller surface area: volume ratio, larger organisms need transport systems to move substances, such as oxygen, around the body to where they are needed. In many animals, this is the bloodstream. They also need specialised exchange surfaces where substances can enter and leave the transport system by diffusion. An example is the lungs in mammals. Exchange surfaces are adapted to increase their surface area to maximise the rate of diffusion.

Organisms living in harsh environmental conditions may reduce their surface area, eg cacti, to reduce loss of substances such as water.

a large surface area - a short distance required for diffusion

the flattened shape of structures such as leaves the alveoli in the respiratory system the villi in the digestive system.