Exchange Surfaces & Breathing Flashcards
Why do small organisms not need specialised exchange systems
- small enough
- take place over the surface of the body
What factors effect the need for an exchange system
- size
- surface area to volume ratio
- level of activity
What does metabolic activity use energy from
- food
- requires oxygen to release the energy
- aerobic respiration
What do the cells of an active organism need
Good supply of
- nutrients
- oxygen
What features make a good exchange surface
- large surface area
- thin barrier: short diffusion distance
- good blood supply: concentration gradient
How can a large surface area be achieved
- folding the walls and membranes
- root hair cell
What is ventilation
The refreshing of air in the lungs
What is the pathway of air into the lungs
- mouth
- trachea
- bronchi
- bronchioles
- alveoli
What are intercostal muscles
- muscles between the ribs
How large are alveoli in diameter
100-300 micrometers
What is the total surface area of the exchange surface in humans (alveoli)
70 m2
How has the body adapted to reduce the distance that gases have to diffuse
- alveolus wall is one cell thick
- capillary wall is one cell thick
- both walls are made of squamous cells
- capillaries are in close contact with alveolus walls
- red blood cells are squeezed against capillaries walls
What is the total distance for diffusion in the alveoli
Two flattened cells
- less than 1 micrometer
How is concentration gradient maintained in humans (lungs)
- good blood supply
- ventilation
What type of cells are alveoli made from
- squamous epithelium
- elastic fibres
What type of cell lines the airways
Ciliated epithelium
What type of cell releases mucus
Goblet cells
What do the C shaped rings of cartilage do around the trachea
- prevent from collapsing
- allows for flexibility
- allows food to pass down the oesophagus
What type of cells are the bronchiole walls made from
- smooth muscle
- elastic fibre
How is the fact that smooth muscle can contract a benefit in the alveoli
Can control the flow of air
- harmful substances in the air
- cannot be controlled: allergic reactions
What is tidal volume
The volume of air inhaled or exhaled in one breath, usually measured at rest
What is vital capacity
The greatest volume of air that can be expelled from the lungs after taking the deepest possible breath
What is a spirometer
A device that can measure the movement of air into and out of the lungs
What precautions have to be made when using a spirometer
- subject has to be fit and healthy
- the soda lime has to be fresh and functioning
- no air leaks in the apparatus
- mouthpiece should be sterilised
- water chamber cannot be overfilled
