Lesson 2 - Compartive Circulatory Systems Flashcards
What is an open circulatory system and in which types of organisms are they found?
In an open circulatory system, hemolymph (transport medium) leaves the open-ended vessels into cavities. Nutrients will diffuse to cells and gases are not transported. Open circulatory systems are found in crustaceans, insects, mollusks and other invertebrates.
An open-circulatory system keeps the fluid mixed around. The “heart” can pump both ways as there are valves on both sides.
What is a closed circulatory system and in which types of organisms are they found?
Blood is always in vessels. There is one loop, which means that blood only goes through the aortic arches once. Gases are not transported by the blood as the diffusion of gases are facilitated by the shape and moisture of the animal. Closed circulatory systems allow for transporting in a certain direction. This is found in worms.
Another type of closed circulatory system is found in fish. More complex behaviour results in a more complex circulatory system. There is still one loop, but gases are transported through the blood. Fish have a two-chambered heart.
Why did the receiving chambers divide through natural selection?
Through natural selection, the receiving chambers divided in order to get more oxygen around the body.
In which types of organisms are three-chambered hearts found?
Amphibians and most reptiles have a three-chambered heart.
Amphibians are unique as they have a third circuit that brings deoxygenated blood to the skin in order for gas exchange to occur. This is called pulmocutaneous circulation.
How many chambers are in a closed circulatory system with two loops and what are the advantages?
There are 4 chambers with 2 atria and 2 ventricles. The advantages of a 2 loop system include the separation of oxygen-rich and oxygen-poor blood. Instead of having mixed blood going around the body, there is oxygen-rich blood going around the body. This allow for greater cell respiration and energy, which results in greater behaviour. Some reptiles, birds, and mammals have the efficient system of four chambers, with the oxygenated blood completely separated from the deoxygenated blood.
What is the difference between the circuit for blood in fish compared to other animals?
Fish have a single systemic circuit for blood, where the heart pumps the blood to the gills to be re-oxygenated (gill circulation). The blood then flows to the rest of the body and back to the heart.
Other animals, such as amphibians, reptiles, birds and mammals, have a pulmonary circuit, where blood is pumped from the heart to the lungs and back, and a systemic circuit, where blood is pumped to the rest of the body and back.
