Exchange and Mass Transport - Insects + Fish Flashcards
What is a problem of a low SA:V?
distances between exterior and interior environments are too great for substances to simply diffuse
Define an exchange surface
any surface across which substances are transferred
When substances leave/enter an organism, what do they go through?
a cell plasma
Name the parts of the respiratory system of insects
Spiracles
Tracheae
Tracheoles
Air Sacs
What are spiracles?
similar to stomata in plants
small holes along the sides of insects which allow air to circulate through the system
contain valves
What are tracheae?
pipes connected to the spiracles that run throughout the body
What are air sacs in insects?
Similar to lungs, used to circulate the air
What are the tracheoles?
similar to capillaries - connect tracheae to body
How do insects circulate the air around their body?
by flexing their body by muscle contraction - this expands and compresses the system and air sacs
this moves air in and out of the spiracles
How are oxygen and water regulated during intense exercise in insects?
Tracheole ends are filled with water.
Lactatic acid builds up in the cells and since it is soluble, it reduces the water potential in the cells, drawing more water in.
This empties the tracheoles and allows oxygen to flow towards the cells quicker
Why are the sizes of insects limited?
If insects were larger, the diffusion pathways would be too long so the SA:V would be too long
too much water would be lost from spiracles
Why do insects open and close their spiracles?
To conserve or lose water - osmoregulation
If the spiracles were open all the time, the air circulation would evaporate a lot of the body’s water in the tracheoles.
What do gills consist of?
Stacks of gill filaments perpendicular to lamellae
Why are there lamallae in gills?
To increase the surface area of the gills
How does countercurrent flow increase the efficiency of gas exchange in fish?
Countercurrent flow means that at all times, there is a diffusion gradient across the entire width of the lamallae.
How would efficiency be affected if the blood ran parallel to the water in gills?
It would start with a higher concentration gradient, however halfway across the lamellae, the gradients would level off and no more diffusion could take place.
