L11 - Gas Echange Flashcards
Define respiration
The sum of the processes that accomplish the movement of O2 from the environment to the cell, and the removal of CO2
How much O2 is in:
a) 1l of air
b) 1l of Fresh Water at 5
c) 1l of Salt Water at 40
a) 210ml
b) 1ml
c) 0.5ml
Define:
a) Anoxia
b) Hypoxia
c) Normoxia
d) Hyperoxia
a) Anoxia: no oxygen
b) Hypoxia: low levels of oxygen
c) Normoxia: normal oxygen levels
d) Hyperoxia: high levels of oxygen
What is Fick’s law?
A law that works out the rate of diffusion
RoD = change in gas grad x SA x diffusion coefficient / the distance diffusion takes place over
Describe 2 ways in which animals have evolved to increase the rate of diffusion
1) Diffusion enhancement:
- increased SA (invaginations etc.)
- Vascularisation or bathed in coelomic fluid
- PP can be increased, or gas converted into non-diffusible form (e.g.: haemoglobin)
- Low diffusion distance
- High diffusion coefficient/high permeability
What are the 2 main forms of Bulk Transport
Ventilation and Circulation
What are the 2 main types of ventilation systems?
- Tidal
- Flow through
Give an example of an animal that uses flow through ventilation
Squid:
- high metabolic demand (both intelligent and fast swimming)
- water enters through a slit, over the Ctenidia and out through a different siphon
- maintained greater pressure in the upper mantle cavity
Give an example of an animal that is an exception to the rule that most aquatic organisms use a flow through system
Sea cucumber:
These use a tidal ventilation system, they pull water into their respiratory tree and then push it back out again of the same route
Why do most aquatic animals use a flow through system?
It is too energy consuming to accelerate or decelerate bulk water
What kind of system do fish have that is very efficient for diffusion of gases
Counter current system:
Blood flows in the opposite direction to the water passing over the gills. This is very efficient as it means there is always a gradient for which O2 to travel from the water to the blood:
- Lower oxygenated blood comes into contact with low O2 blood, but has enough pull to take it
- Moderately oxygenated blood comes into contact with highly oxygenated water
Describe how water is passed through a fishes ventilation system at slow swimming speeds and high swimming speeds
Slow: fish take water into their mouth cavity, shut the mouth and then exert pressure on the cavity, pushing the water out and over the gills, setting up an almost continuous pressure difference between the 2 cavities.
Ram/fast: as fish are swimming at a certain speed they switch from gulping to allowing the water to flow over their gills as a result of their swimming speed.
How do lamprey ventilate when they are attached to a prey?
They use tidal ventilation when they aren’t moving
