Circulatory Systems Flashcards
What is the circulatory systems main purpose?
To transport substances like carbon dioxide, oxygen and digestive products around the body
In very small organisms how are substances moved around the body?
Diffusion
What is the definition of diffusion?
The net movement of molecules or ions from a region of their high concentration to a region of their low concentration by relatively slow random movements of molecules
What do more complex organisms need in order to move substances around their body?
Blood to carry vital substances and a heart to pump it - a circulatory system
What type of circulatory system do insects have?
An open circulatory system
How does blood circulate in insects?
A simple heart pumps blood out into cavities surrounding the insects organs. Substances then diffuse between the blood and cells.
How does blood get drawn back into the heart muscle in insects?
When the heart muscle relaxes, blood is drawn from the cavities back into the heart through small valved openings along its length.
What circulatory system is found in fish?
A single circulatory system
What type of blood is pumped into the gills of fish?
Deoxygenated blood
How does gaseous exchange take place in gills?
There is diffusion of CO2 from the blood into the water surrounding gills, and diffusion of O2 from water into the blood
Where does blood leaving the gills go?
Blood flows round the rest of the body before returning to the heart
Where is the double circulatory system found?
In birds and mammals
What does the right ventricle of the heart pump and where?
Deoxygenated blood to the lungs, where it receives oxygen
Where does oxygenated blood from the lungs then do?
Return to the heart to be pumped a second time -by the left ventricle, to the rest of the body
Why is it an advantage for blood to be pumped twice by the heart?
It gives blood returning from the heart an extra boost meaning it reduces the time it takes for blood to circulate, thus giving mamals and birds a higher metabolic rate
