Fish Flashcards
1
Q
Difficulty obtaining oxygen from water
A
- Water contains less oxygen than air
- Diffusion rates much slower
- Dense and viscous so more difficult to move
2
Q
Cartilaginous fish (cartilage skeleton)
A
- Less efficient ventilation system as no mechanism to force water over gills
- Must keep swimming
3
Q
Parallel flow
A
- Blood travels in same direction as water
- Equilibrium reached part way across lamellae so conc gradient not maintained
- Less diffusion of oxygen (only 50% saturation with oxygen)
4
Q
Bony fish (bone skeleton)
A
- 4 pairs of gills in pharynx
- Gill supported by bony gill arch
- Gill filament (2 in each gill) = large SA and filled with capillaries
- Gill rakers- filter water and trap prey to prevent damage to filaments
- Filament has gill plates/ lamellae = SA (exchange site)
5
Q
Ventilation I
A
- Mouth opens, operculum closes
- Floor of mouth/ buccal cavity is lowered
- Volume of cavity increases and pressure falls
- Water flows/ pilled in due to the pressure difference (greater out)
6
Q
Ventilation II
A
- Mouth closes
- Floor of buccal cavity is raised
- Volume decreases and pressure increases
- Water forced across the gills
- Operculum forced open and water flows out as greater inside
7
Q
Countercurrent flow
A
- Blood flows across gill plates in opposite direction to water
- Conc/ diffusion gradient of oxygen maintained across the entire gill as water has higher conc than blood along entire length
- Higher saturation of blood with oxygen
- More efficient- equilibrium never reached
8
Q
Heat exchanger
A
- Cold blood in arteries from gills passes close to warm blood in veins in opposite direction
- Heat from warm blood raises temp of cold blood before reaching capillaries
- Temperature gradient maintained across the entire length of the heat exchanger
9
Q
Out of water
A
- Water separates gill filaments so gills dry out
- Filaments stick together and gills collapse
- Lower SA for gas exchange and diffusion
- Water needed for diffusion of gases
- Not enough exchange to survive = die
