7.3 Circulatory system of a mammal Flashcards
Why do large organisms have exchange surfaces
. All organisms exchange material between themselves and their environment
. For small organisms this can occur just by diffusion over their body surface, however larger organisms have smaller surface area to volume ratios so the needs of the organism can’t be met by diffusion alone
. This means specialist exchange surfaces are required to absorb nutrients and respiratory gases, and remove excretory products
What is a transport system
. It is required to take materials from cells to exchange surfaces and from exchange surfaces to cells
Then they are transported between exchange surfaces
Whether or not there is a specialised transport medium needed for exchange, or if it is is circulated by a pump depends on two factors:
. The surface area to volume ratio
. How active the organism is
The lower the surface area to volume ratio, and the more active the organism, the greater the need for a specialised transport system with a pump
Name 4 features of a transport system
Suitable medium
Form of mass transport
Closed system of vessels
A mechanism for moving transport medium
- A suitable medium in which to carry materials eg blood. It is normally a liquid based on water because water can dissolve substances in it and move them around easily. It can also be a gas eg air breathed in and out of lungs
. A form of mass transport where the transport medium is moved around in bulk over large differences: more rapid than diffusion,
. A closed system of tubular vessels that contains the transport medium and forms a branching network to distribute it to all parts of the organism
. A mechanism for moving the transport medium within vessels: this requires a pressure distance between one part and another
Transport systems need a mechanism for moving the transport medium within vessels, which requires a pressure distance between one part and another
How is this achieved in animals
. Animals use muscular contraction either of body muscles or a specialised pumping organ eg heart
Transport systems need a mechanism for moving the transport medium within vessels, which requires a pressure distance between one part and another
How is this achieved in plants
Plants rely on natural, passive processes eg evaporation of water
Name another 3 features of a transport system
Control direction of flow
. Control power of flow
. Mechanism for water and gas
. A mechanism to keep mass flow in one direction, eg valves
. A means of controlling the flow of the transport medium to suit the changing needs of different parts of the organism
. A mechanism for the mass flow of water or gases, eg intercostal muscles and diaphragm during breathing in mammals
What type of circulatory system do mammals have
. Closed, double circulatory system
in which blood is confined to vessels and passes twice through the heart for each complete circuit of the body
Why do mammals have a double circulatory system
. Because when blood is getting pumped to tissues all around the body, it needs a high pressure to be able to reach all the cells
Whereas when blood is getting pumped from the heart to the lungs, it needs a low pressure as it isn’t going far, and the lungs are filled with air which creates very little resistance.
Why do mammals have to have a high blood pressure
They need to deliver substances around the body quickly as mammals have a high body temperature and hence a high metabolic rate
What are the 3 vessels that make up the circulatory system of a mammal
. Arteries
. Veins
. Capillaries
What happens once the arteries bring oxygenated blood to cells
. The oxygen can diffuse in
This is rapid because it takes place over a large surface area , across short distances and there is a steep diffusion gradient
What blood vessel brings deoxygenated blood from heart to lungs
Pulmonary artery
What blood vessel brings oxygenated blood from lungs to heart
Pulmonary vein
What blood vessel brings oxygenated blood from the heart to around the body
Aorta (artery)
