Transport systems in animals 8.1 Flashcards
Types of transport in smaller organisms?
Diffusion, Osmosis, Active Transport, Endocytosis, Exocytosis
Why do animals need a transport system?
Our metabolic demands are too high, we need oxygen and food at a massive scale which cannot be met by diffusion.
Our SA: V ratio is fat too big for diffusion to take place fast enough
We produce hormones and enzymes in on a place that might be needed a lot further away
We need digested food into glucose in every cell of the body
We need our waste to be removed quickly and it has to travel far.
What do circulatory systems have in common?
They have a liquid transport medium e.g the blood
They have blood vessels to transport it in
They have a pumping mechanism to move the transport medium around the body.
There are many types of circulatory systems but they all have these characteristics.
If they move fluid in mass quantities, it’s called a mass transport system.
Open Circulatory System
This is where there aren’t too many blood vessels and the transport medium is just flowing through the body cavity where gas exchange happens. This normally occurs in invertebrates like slugs. Their hearts are in the middle and form a long membrane. Their body cavity is called a haemocoel and their transport medium is haemolymph. it doesn’t transport oxygen as that is the respiratory system, it just transports nutrients and food.
Single Closed Circulatory System
Found in fish and worms. This is where the blood only travels around the body once. It is pumped out of the heart and around the body through the blood vessels where gas exchange occurs by the diffusion of gases across the walls of the blood vessels. The blood will flow through two sets of capillaries, the first will be the exchange of oxygen and CO2 and the next will be the exchange of substances. The blood will return back to the heart slowly so animals with this system are pretty inactive.
Why are fish the only active animals with a single circulatory system?
They have countercurrent gas exchange system which means their oxygen intake is very high, their body weight is also supported by water and they don’t have to maintain their body temperature, so they have a decreased metabolic demand and high oxygen so can be active.
Double Closed Circulatory System
Found in birds and mammals. This is where the blood goes through the heart twice in one cycle. Blood is pumped from the heart to the lungs in order to get oxygen and remove CO2 and then it returns to the heart where it is pumped all around the body for gas exchange to occur. It has high pressure and fast flow of blood so the exchange can be done quickly.
