C8- Transport in Animals Flashcards
Why do animals need specialised transport systems
high metabolic demands
small sa:v
molecules such as hormones made in one place but needed in the other
waste products from respiration need to be transported to excretory organs
Common features of circulatory systems
Liquid medium to transport substances
Vessels to carry the transport medium
A pumping mechanism to move fluid around the body
Disadvantages of open circulatory systems
Steep concentration gradients cannot be maintained by slow moving haemolymph
Diffusion is not efficient
The system is fixed
–> Doesn’t change if the metabolic demands of the insect changes
Open circulatory system
one in which there is a mixing of the blood and interstitial fluid (fluid that fills the space surrounding cells) to make up the haemolymph
Low pressure system
no blood vessels
Insects Circulatory system
Open circulatory system
cells obtain nutrients directly from the haemolymph
Explain why circulatory systems are found in multicellular organisms but not in unicellular organisms
Unicellular organisms have large SA : V ratio so diffusion distances small and metabolic demands low so diffusion can supply and remove substances quickly and efficiently enough
Multicellular organisms have small SA : V ratio, so long diffusion distances. Metabolic demands are high – diffusion alone can no longer supply all needs quickly and efficiently enough
Describe the function of a circulatory system
Transports requirements for metabolism, e.g., oxygen, food molecules, to cells
removes waste products of metabolism from cells and carries them to excretory organs
transports materials made in one place to another place where they are needed
Why do multicellular organisms have specialised transport systems
Small SA:V
Generally active
–> High metabolic demand and large amounts of waste products produced
