8.1 Transport Systems In Multicellular Organisms Flashcards
what do circulatory systems carry around the body
gases such as oxygen and carbon dioxide
nutrients
waste products
hormones
what are common features of a circulatory system
a liquid transport medium that circulates around the system eg blood
vessels that carry the transport medium
a pumping mechanism to move fluid around the system
what an open body cavity called
haemocael
what’s an open circulatory system
a system where very few vessels contain the transport medium and its pumped straight from the heart to the animals body cavity the transport medium comes into direct contact with the tissues and cells and this is where exchange takes place
what pressure is the transport medium under in an open circulatory system
low pressure
how does exchange occur in open circulatory systems
in the open body cavity the transport medium comes into direct contact with the tissues and cells and this is where exchange occurs
through what vessel does the transport medium return to the heart in, in an open circulatory system
and open ended vessel
what’s insect blood called
haemolymph
what animals typically have open circulatory systems
invertebrates and insects
what does insect blood transport in open circulatory systems
nitrogenous waste products, food and the cells involved in defence against disease
but not co2 or o2
where does gas exchange take place in insects
the tracheal system
what’s insects body cavity and heart like
spilt by a membrane and the heart extends along the length of the thorax and abdomen
what’s the disadvantage of open circulatory system in insects
the haemolymph circulates but a steep conc gradient can’t be maintained for efficient diffusion and the amount of haemolymph flowing to a particular tissue cannot be varied to meet changing demands
what’s a closed circulatory system like
here the blood doesn’t come directly into contact with the body cells the heart pumps the blood around quickly and under high pressure and the blood returns directly to the heart substance leave and enter blood by diffusion through vessel walls
what pressure is the blood in a closed circulatory system under
relatively high pressure
how are substances exchanged in a closed circulatory system
substances leave and enter blood by diffusion through the walls of the blood vessels
how can the amount of blood flowing to particular tissues in a closed circulatory system be controlled
by narrowing or widening the blood vessels
in which animals are closed circulatory systems found
fish and all mammals
why are specialised transport systems needed
high metabolic demands ( need lots of O2 and produce lots of waste products)
small sa:v ratio this means diffusion distances are bigger and sa to remove substances gets smaller
molecules or hormones may be made in one’s place but needed in another
waste products need to be removed from cells and transported to excretory organs
food will be digested in one organ system but needs to be transported to every other cells for use in respiration/other
what are single closed circulatory systems
where the blood flows through the heart and is pumped out to travel all around the body where it passes through two sets of capillaries before returning to the heart so the blood only travels through the heart once for each complete blood circulation
what happens each time the blood passes through set of capillaries in a single closed circulatory system
the first time oxygen and carbon dioxide are exchanged and the second set of capillaries are in the different organ system and substances are exchanged between the blood and cells
what happens to the blood pressure and the blood passes through the two sets of capillaries
as a result of passing through these two sets of very narrow vessels the blood pressure in the system drops considerably so the blood returns to the heart quite slowly
how efficient are single closed circulatory systems and why and what is the exception
not very efficient as the blood returns to the heart slowly after passing through the capillaries and activity of animals with this system tends to be quite slow
fish are an exception due to countercurrent system
how does fishes countercurrent system allow for an effective circulatory system
it allows them to take lots of O2 from the water and their body weight is supported by water and they don’t have to maintain their body temp so this reduces their metabolic demand
what are double closed circulatory systems and who has them
birds and most mammals have them as they are very active and have to maintain their own body temp the double system involves two separate circulations
1 the blood is pumped from the heart to the lungs to pick us oxygen and unload carbon dioxide then returns to the heart
2 blood flows through the heart and is pumped out to travel all around the body before returning to the heart again
summary of double closed circulatory system
the blood travels twice through the heart for each circuit of the body (lungs and then other organs) and each circuit only passes through one capillary network which means relatively high pressure and so fast flow of blood can be maintained
what’s the circulation to the lungs called in DCCS
pulmonary circulation
what’s the circulation to the other organs called in DCCS
systematic circulation
why are double closed circulatory system effective
in each circuit the blood travels through it only passes through one capillary network not two which means it has a relatively high pressure and a fast blood flow can be maintained
