BIO2242 – LECTURE 9
Aerobic cellular respiration consumes oxygen and produces carbon dioxide:
The primary role of RBC is to:
Repair cellular damage
Localise respiratory enzymes
Increase blood oxygen carrying capacity = do this with the help of hemoglobin
Environmental oxygen is not constant in space or time:
Cold water has more oxygen because its turbulent water, so it’s constantly mixed
with air. As water warms up, it loses oxygen.
Air pressure is lower at high altitude due to the weight of the air.
Respiration in water:
If the animal is big, they increase the SA so that there is a short distance between
the cells and the environment.
Respiratory organs increase diffuse SA:
Animals with different body shapes need a special area devoted to increasing SA.
Sea star = Invaginations of the coelom which makes up a large surface of the
coelom that is directly exposed to the environment for gas exchange
Marine worm = parapodia which have a large surface and a large supply of blood
from the closed circulatory system
Clam = Cnedia used for feeding and gas exchange
Crayfish = another form of gill
Gills are efficient in water but not air:
Most animals that live in water and have a circulatory system have invaginations,
so they increase the SA by branching.
In fish, they have red gills because they are filled with blood and this blood is
highly enriched with oxygen. Each of the lamella have a dense network of small
Water is hard to pass through the gills because it is very heavy. However, with
the help of the mouth at the front and the operculum at the back, this is able to
occur. They open their mouths to let water in, while the operculum is closed.
Then, they close their mouths and open their operculum to draw water out from
the cavity. They also raise the bottom of their mouth cavity.
Gill area is proportional to activity level:
Opercular pumping takes up energy.
Ramming yourself through the water, and the water flows in.
The main disadvantage of breathing water is:
Its temperature Its oxygen concentration
Its density = also important but not as important as the above
Whats important is the way water flows over the gills, and the way blood flows
through the gills. Idea of maintaining a countercurrent flow is to maintain a conc.
Gradient, which is relatively large. So it’s maximizing the conc. gradient in your
blood (low) and conc. Gradient in the water (high).
Respiration in air:
Moist skin is important form of respiration.
Gills are flimsy and tend to collapse so they are not efficient.
Insects developed trachea, while mammals developed lungs.
Tracheae is a system of tubes, which is very efficient in getting oxygen to every
cell. You cannot ventilate them so they have a low transport capacity – you can
get air, but once the air is in, you can't get them in and out very efficiently.
The tracheole are directly at the end of the tracheae, contact directly with all the
tissues in the body. The tracheole are filled with fliud, as oxygen eventually
needs to go into a liquid environment so they don't dry out.