Circulatory system of a mammal Flashcards
why do mammals need a transport system?
- needs of organism can’t be met by body surface
- specialist exchange surface needed to absorb nutrients + gas
- increasing size- DECREASES SA:V ratio
what two things decide whether the is a specialised transport system and whether it is circulated by a pump?
- the SA:V ratio
- how active the organism is
the LOWER the SA:V ratio and the MORE ACTIVE the organism, the greater need for a specialised transport system with a pump
what are the common features of transport systems in mammals?
- suitable medium to carry liquid
- a form of mass flow transport, where transport medium is moved around in bulk
- a closed system of tubular vessels containing transport medium
- a mechanism for moving the transport medium in vessels
- a mechanism maintain the mass flow movement in one direction VALVES
- a way of controlling the flow of the transport medium- suit changing needs of different parts of organism
what does a mechanism for moving transport medium within vessels require? and how is it achieved?
requires a pressure difference between one part of system and another
- animals use muscular contraction eg heart
- plants rely on passive natural physical process eg evaporation of water
what type of system do mammals have?
closed blood system where blood is confined to vessels
what is a double circulatory system?
where the blood passes twice through the heart for each complete circuit of the body
why do mammals have a double circulatory system?
when blood is passed through the lungs the pressure is reduced, the blood is returned to the heart to boost the pressure and speed up circulation.
what are the three vessels that make up the circulatory system of a mammal?
veins, arteries and capillaries
how does blood move from blood vessels to cells?
diffusion
why is diffusion from blood vessels to cells rapid?
it takes place over a large surface area, across short distances and there is a STEEP DIFFUSION GRADIENT
