BIO2242 – LECTURE 10
All animals have a circulatory system:
This heart comes from which type of animal?
Both mammals and birds have 4 chambers.
Fish have a single atrium and single ventricle
It is the exchange of chemicals, which is a passive process.
If you are small with a few cell layers in contact with the water, you can uptake
materials directly from the environment.
Circulatory systems are needed when diffusion distances become too big.
For animals that are larger, and not flat and has a tubular gut that doesn’t
distribute itself through the body.
Insect = large amount of fluid inside (hemocoel), but it also has a pump, and
Sinus = large space where liquid goes out of the vessels, where they squish
around until it gets taken up.
They no longer have an open circulatory system. They have developed a fully
closed on which is related to their high levels of activity.
Advantage of open circulatory system is that when they have a large volume of
liquid, its very hard to maintain pressure in a fast flow.
Large body, so they have closed circulatory system, with a dorsal vessel.
Fish = single circuit = have single atrium and single ventricle where it pump
blood through gills, where gills change oxygen depleted blood into oxygen rich
blood. Oxygenated blood flows from the gills to the rest of the body back to
various capillary beds of muscles or guts or different parts of the body, where it
then returns to the heart.
Human = Double circuit = one dedicated to oxygen exchange (lungs), where we
can enrich our blood with oxygen. And the other, which is the visceral circuit that
passes through the rest of the body where we have blood being depleted from
oxygen by various tissues. Our blood is red. Blue blood in humans = no oxygen
Other animals = oxygenated blood is blue Single circuit blood flow – fish
2 chambered heart – single atrium and ventricle.
Blood goes from A to V, where V provides the main pumping force for
contraction and as a result, theres only one source of pressure (V), it means that
the pressure is determined completely by that one chamber, and thus, the source
of pressure is the same for the gills and the body. But the pressure decreases as it
goes away from the heart. The pressure starts off very high in the gills, but then
drops when it goes back into the body, and the heart.
Double circuit blood flow – Amphibian/Reptilian:
They have two separated circuits. One circuit goes to the lungs – starts off in the
L atrium, the blood from the L atrium goes into the ventricle, and into the lungs,
back into the L atrium and the blood from the rest of the body starts from the R
atrium and goes to the ventricle, and comes back into the R atrium.
They have a heart where there are two inputs, but there is only one ventricle,
hence only a single pump.
They can redistribute their blood stream as they can regulate what part of the
blood goes into which exit tube, thus create differences b