gas exchange in animals Flashcards
bbs bitesize
alveoli
definition
Tiny air sacs in the lungs, where gas is exchanged during breathing.
bronchi
definition
The plural of ‘bronchus’. The bronchi are the two major air tubes in the lungs.
bronchioles
definition
The many small, branching tubules into which the bronchi subdivide.
capillary
definition
Tiny blood vessels with walls one-cell thick where exchange of materials occurs.
carbon dioxide
definition
A gaseous compound of carbon and oxygen, which is a by-product of respiration, and which is needed by plants for photosynthesis.
cartilage
definition
A strong, flexible type of connective tissue. It forms C-shaped rings in the trachea that keep the airway open.
concentration gradient
definition
The difference in the concentration of a chemical across a membrane.
Villi
definition
Finger-like projections in the small intestine that provide a large surface area for the absorption of food.
Ventilation
definition
Breathing in and out.
Trachea
definition
The windpipe, the tube that leads from the mouth towards the lungs.
Respiratory system
definition
The organ system where air is taken into and out the body, and gas exchange happens.
pleural membranes
definition
Thin, moist membranes surrounding the lungs that make an airtight seal.
pleural membranes
definition
Thin, moist membranes surrounding the lungs that make an airtight seal.
oxygen
definition
Gaseous element making up about 20% of the air, which is needed by living organisms for respiration.
intercostal muscles
definition
Sets of muscles between the ribs which raise and lower the rib cage.
human thorax
The ribs and upper backbone, and the organs found in the chest.
diaphragm
definition
A large sheet of muscle that separates the lungs from the abdominal cavity.
epithelial cell
definition
A cell that forms part of an epithelium.
exchange surface
definition
An area of the lungs that is adapted for efficient transfer of gasses.
Diffusion
It is important to remember that the particles:
- 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
surface area:volume ratio
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.
Why do larger organisms need transport system s to move substances around the body?
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.