Circulatory system Flashcards
Do insects have an open or closed circulatory system?
open circulatory system
Do mammals and fish have an open or closed circulatory system?
closed circulatory system (blood is confined to blood vessels only)
Double circulatory system
One in which the blood flows through the heart twice for each circuit of the body
Single circulatory system
One in which the blood flows through the heart once for each circuit of the body
Transport
The movement of substances such as oxygen, nutrients, hormones, waste and heat around the body
What are the three main factors that influence the need for a transport system?
Size
Surface area to volume ratio
Level of metabolic activity
Why do very small organisms/ animals don’t need a separate transport system?
Because they have a very high surface area to volume ratio, they can rely on diffusion for the exchange of molecules with their environment eg oxygen
Why do larger organisms/animals have a seperate transport system?
*have a much lower surface area to volume ratio, with the majority of cells a large distance from the surface of the organism
*Larger organisms are often very active, high demand for oxygen for aerobic respiration->cant rely on diffusion alone
What is the circulatory system like in fish?
-Deoxygenated blood is pumped by the heart through blood vessels to the gills
-In the gills, the blood passes through capillaries
-Oxygen diffuses from the water into the blood
-The oxygenated blood now passes from the gills through blood vessels to the body tissues
-when it reaches the body tissues the blood again passes through
capillaries where oxygen diffuses from the blood to the cells that need it
-Finally, the deoxygenated blood now returns in blood vessels back to the heart
What is mass transport?
When molecules are carried in a transport medium such as blood through a circulatory system
What is the problem with a single circulatory system?
When the blood leaves the heart, the pressure of the blood is high and the blood is moving rapidly
However the blood then passes through two sets of narrow capillaries (in gills and as it passes the body tissues), slowing down the blood and loses pressure, limits how rapidly oxygen can be delivered to the body cells
What is the circulatory system in mammals like?
-deoxygenated blood is pumped under high pressure from the heart to the lungs
-in the lungs, the blood passes through narrow capillaries and oxygen diffuses through the air into the blood(moving relief slowly with low pressure bc of capillaries)
-oxygenated blood returns back to the heart which pumps the blood at high pressure around the body
-As it passes through the body tissues, the blood passes through capillaries and oxygen diffuses to the body cells
-the low pressure deoxygenated blood now makes its way back to the heart to be pumped again
Advantage of a double circulatory system?
Ensures that the blood moves to the body tissues rapidly and under high pressure - a double circulatory system can deliver oxygen more efficiently than a single circulatory system
What is an closed circulatory system?
The blood is always contained in blood vessels as it travels to and from the heart
• blood can move relatively rapidly
•amount of blood passing to different organs can be controlled by constricting or dilating blood vessels
What is an open circulatory system?
The haemolymph in insects is npt carried in vessels
•so it cannot move rapidly around the insect
•the insect cannot easily change the amount of haemolymph movinf to different parts of its body
