Transport in animals 3.2.1 Flashcards
Why do we have a circulatory system?
Within all living organisms, substances need to be moved from one place to another.
What sort of substances need to be moved throughout a living organism?
- Nutrients (glucose)
- Oxygen
- Waste - lactic acid/carbon dioxide etc.
- Hormones
Why do small organisms not require a bloodstream (transport system)?
As they can rely on simple diffusion for all of their substances - due to their large surface area to volume ratio.
State 3 factors influencing the need for a transport system
- Size
- Surface area to volume ratio
- Level of metabolic activity
How does size influence the need for a transport system?
- In large organisms, the diffusion pathway is increased, due to the many layers of cells within them.
- This causes the diffusion distance to be too long and less material will reach the cells deep inside the body.
How does SA:V ratio influence the need for a transport system?
- Large animals have a small surface area to volume ratio as their volume is much larger than their surface area.
- Therefore, they require a system which allows them to meet their demand of substances.
How does the level of metabolic activity influence the need for a transport system?
- Large organisms have high metabolic rates
- Diffusion alone would not be able to intake all the substances required for large, active warm blooded animals.
Name 4 features of a mass flow transport system.
- Suitable transport medium (blood)
- A pump to create pressure (heart)
- Exchange surfaces that enable substances to enter and leave the blood (capillaries)
- Vessels/tubes to carry the blood by mass flow
State the two types of circulatory systems
- Open and closed
What type of organism has an open circulatory system?
Invertebrates, which have no vessels
State the working features of an open circulatory system
- Have a long muscular heart that pumps haemolymph in and out of cavities at low pressure
- The heart has pores called Ostia which haemolymph enters through
- The haemolymph is pumped towards the head by peristalsis (involuntary constriction and relaxation of muscles - wave like motion)
- Less energy is required for haemolymph to be distributed
Name 2 disadvantages of an open circulatory system
- Blood pressure is low and blood flow is slow
- Circulation of blood (haemolymph) may be affected by movements/lack of movements of the body
What is the fluid known as in an open circulatory system
Haemolymph
What is the large cavity known as in an open circulatory system
Haemocoel
What influences the movement of haemolymph within the haemocoel
Due to the movement of the organism
Name 4 features of a closed circulatory system
- Blood is enclosed in blood vessels
- High blood pressure
- This means that blood travels faster so it is more efficient
- Transport is independent of body movements
What are the two subsystems of closed circulatory systems?
Single and double
Do fish have an open or closed circulatory system?
Closed
State the sequence of blood flow in fish
Heart -> gills -> body -> heart
What takes place in the gills?
Gas exchange
How many times does blood flow through a fish in a single circuit?
Once
What is counter current and where does it take place?
Takes place in the gills
- Water carrying oxygen flows in one direction and deoxygenated blood flows in another direction
How are counter currents beneficial to fish?
As they allow a steep concentration gradient to be maintained, therefore equilibrium is not reached and diffusion is constantly taking place
Why do birds and mammals have a double circulatory system?
As they need far more oxygen than fish, therefore require a constant internal environment which requires a lot of energy
