Transport in animals Flashcards
why do animals need specialised transport systems
- the metabolic demands of multicellular animals are high, so diffusion across long distance would not supply the quantities needed
- the SA:V ratio gets smaller as organims get bigger so not only do the diffusion distance increase but the amount of surface area available to absorb or remove substance become smaller
- molecules prodcued or broken down in one area need to be transported to another area where they are required
- waste products need to be removed and transported to excretory organs
describe open circulatory systems
- no vessels
- blood pumps at low pressure
- circulation is slow
- little control over direction of flow
occurs in insects
what is haemolymph
is a fluid, similar to blood in vertebrates, that circulates in the interior of the arthropod body remaining in direct contact with the tissues and cells
it doesnt carry oxygen or CO2
lies in the body cavity (hemocoel)
it carries nutrients and waste products
describe close circulatory system
-has continuous system of vessels which blood enclosed at all times
- blood is pumped by a heart through vessels
- blood pumps at higher pressure and flow is rapid
- tissue fluid bathes cells
explain single circulatory systems
blood passes through the heart once in each circulation, therefore travels in a simple loop
eg in fish: heart-gills-body-heart
explain double circulatory systems
blood passes through the heart twice in each circulation, therefore travels in a double loop
eg: heart-lungs-heart-body-heart
describe the pressure differences in double circulatory system
- in single the blood pressure is limited by the delicate nature of tiny capillaries in the gills
- in the double the blood pressure can be high in the systemic circuit while remaining low and safe in the pulmonary circuit.
this allows animals to be more active, since blood can reach their respiring tissues faster due to higher pressure
what are arteries
