Gas exchange Flashcards
(13 cards)
1
Q
Name three features of an efficient gas exchange surface
A
- Large surface area
- Short diffusion pathway
- Concentration gradient
2
Q
Why can’t insects use their bodies as an exchange surface?
A
They have a waterproof exoskeleton make of chitin, as well as a small surface area : volume ratio to conserve water
3
Q
What are the three main features of an insect’s gas transport system?
A
- Spiracles = pores in the exoskeleton which can be opened or closed
- Tracheae = large tubes extending through the body, supported by cartilage rings
- Tracheoles = smaller branches that divide off the tracheae
4
Q
How does gas exchange work in insects?
A
- Gases move in and out of spiracles into trachea
- Diffusion gradient allows oxygen to diffuse in, and carbon dioxide to diffuse out
- Contraction of muscles in the trachea allow this to happen
5
Q
Name two main features of a fish’s gas transport system
A
- Gills = supported by arches and have gill filaments across them
- Lamellae = on gill filaments, and provide them with larger surface area. Blood and water flow across them by counter-current flow
6
Q
How does gas exchange work in fish?
A
- Fish opens mouth to allow water in, then closes it to increase pressure
- Water passes over lamellae and oxygen diffuses into blood (counter-current flow)
- Waste carbon dioxide diffuses into water and flows out of gills
7
Q
How does counter-current flow benefit fish?
A
- Maintains steep concentration gradient
- Water always next to blood of a lower oxygen concentration
- Rate of diffusion constant along whole length of the gill
8
Q
Name three leaf adaptations for gas exchange
A
- Thin and flat = provides short diffusion pathway and large surface area : volume
- Many pores in underside of leaf (stomata) = allows gas to enter easily
- Air spaces in mesophyll = allows gases to move around leaf
9
Q
How do plants limit water loss?
A
Guard cells on stomata = can open and close as needed
10
Q
What is the process of inspiration?
A
- External muscles contract, internal muscles relax
- Rib cage moves up and out
- Diaphragm contracts and moves downwards
- Volume of thorax increases
- Air pressure higher outside lungs, so air moves in
11
Q
What is the process of expiration?
A
- External muscles relax, internal muscles contract
- Rib cage moves in and down
- Diaphragm relaxes and domes
- Volume in thorax decreases
- Pressure greater in lungs, so air moves out
12
Q
How do you calculate pulmonary ventilation rate?
A
Tidal volume x breathing rate
13
Q
A
