3.1 Exchange Surfaces Flashcards
(46 cards)
What are the three main factors hat affect the need for an exchange system?
Size (single celled and multicellular organisms)
Surface area to volume ratio
Level of activity
What are the features of a good exchange surface?
A large surface area
A thin diffusion distance
A good blood supply (steep concentration gradient)
Define alveoli.
Tiny fold of the lung epithelium to increase the surface area.
What are bronchi and bronchioles?
Smaller airways leading to the lungs.
What is the diaphragm?
A layer of muscle beneath the lungs.
What are intercostal muscles.
Muscles between the ribs.
Contraction of what muscles raises the rib age?
External intercostal muscles.
What is the trachea?
Main airway leading from back of the mouth to lungs.
What is ventilation?
The refreshing of the air in the lungs, so that there is a higher oxygen concentration than in the blood, and a lower carbon dioxide concentration.
How are the alveoli specialised?
Large surface area
Thin layer of moisture
They have elastic fibres in their walls
Constant blood supply
Explain inspiration.
Diaphragm contracts
External intercostal muscles contract
Ribs raise
Volume increases pressure decreases
Explain expiration.
Diaphragm relaxes
External intercostal muscles relax
Ribs fall
Volume decreased pressure increases
What do the internal intercostal muscles do?
Can contract to push air out more forcefully during exercise or coughing or sneezing
What are elastic fibres?
Protein fibres that can deform the recoil to their original size.
What is smooth muscle?
Involuntary muscle that contracts without the need for conscious thought.
What helps prevent collapse during inspiration?
Cartilage.
What shape is the cartilage?
C-shaped for flexibility and allows food to pass down oesophagus.
What is the wall of bronchioles compromised of?
Smooth muscle and elastic fibres.
What does smooth muscle do?
Can contract and constrict the airway if there are harmful substances in the air
Not voluntary
How does smooth muscle relax?
Elongated by elastic fibres which recoil to their original size and shape
What is oxygen uptake?
The volume of oxygen absorbed in one minute.
Tidal volume?
The volume of air inhaled or exhaled in one breath 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 precautions need to be taken with a spirometer?
- healthy and free from asthma
- fresh soda lime
- no air leaks
- sterilised mouth piece
- water chamber must not be overfilled
