Gas Exchange Flashcards
What is gas exchange?
Gas exchange is the inhalation of O2 into the body, used to produce ATP in cells, and the exhalation of CO2, a by-product of these reactions.
What is the primary function of the respiratory system?
Efficient way to bring oxygen in and remove waste products.
How is respiration related to environment? Provide an example.
Similar to other functions throughout an animal’s body, the way an animal breathes is largely dependent upon the environment in which it lives.
O2 in aquatic environment:
* Lower diffusion rate & solubility
* Less available O2 in a given volume of fluid
We can conclude that animals need to use more energy to run an
O2 ’pump’ or need an more efficient O2 ‘pump’ in water.
What is Fick’s first law?
Fick’s first law a solute will move from a region of high concentration to a region of low
concentration across a concentration gradient.
What is Fick’s second law?
Fick’s second law the amount of substance diffuses across a surface is proportional to the
area of that surface and inversely proportional to the distance across which it diffuse.
Name and describe the two components of external respiration
Ventilation - active
movement of respiratory
medium
* Perfusion: gas uptake
What is internal respiration?
Use of O2 to make energy
What is important about perfusion and ventilation in gas exchange?
for gas exchange to be efficient, the volumes involved in ventilation and perfusion should be compatible. Ventilatory structures and perfusion structures have thus evolved to maximize said compatibility.
How does scaling affect external respiration? Why?
Determines ventilation mechanism. Respiratory systems get more complex as animals get larger, since increase in size correlates with larger diffusion distances and a drop in SA:V ratio.
How does ventilation occur for small scaled animals?
For small multicellular organisms, diffusion across the outer membrane is sufficient to meet their oxygen needsThis is what is known as direct diffusion. The cells are close enough to the surface of the body and are kept moist for quick diffusion. Their flatness also increase the available SA. Large SA:V.
What is ventilation like for large scaled animals?
- SA:V small, X and A
must improve
oxygen uptake - Need specialized
structures, such as
gills or lungs
What are examples of structures that increase SA?
gills and lungs
How do gills work? Why is this possible?
Dissolved oxygen diffuses across the gills from water and directly into the bloodstream or coelomic fluid. O2 concentration in water is higher than in the gills.
What groups are gills found in?
Gills are found in mollusks, annelids, and crustaceans.
How do gills increase SA?
- Gill arch (larger blood vessels)
- Gill filaments (smaller blood vessels)
- Gill lamellae (capillaries)
What is unidirectional flow? What animals use it?
Unidirectional flow: medium enters at one point and exits via another; fish, insects (spiracular), birds
What kind of blood flow is in fish gills?
blood flows in opposite direction of blood: countercurrent exchange/flow
Why is countercurrent exchange more efficient in gills than same direction?
diffusion would be restricted to a smaller distance; countercurrent is therefore more efficient.