Unit 3 - Circulatory systems Flashcards
Give 5 reasons why specialist transport systems are needed
-metabolic demands of most animals is high
-SA:V decreases as animal size increases so diffusion distances increase whilst SA avaliable becomes relatively smaller
-molecules are made in one place but needed in another
-food will be digested in one organ system but needs to be transported to every cell
-waste products of metabolism need to be removed from cells and transported to excretory systems
As an organism gets larger what happens to the diffusion distance?
It gets larger
Why does a greater level of activity in an organism increase demand for glucose and oxygen?
-more activity requires more energy
-more energy requires more aerobic respiration
-which requires more reactants (oxygen and glucose)
Why does a greater volume of an organism mean a greater demand?
-greater volume means greater number of cells
-each cell requires energy
-so demand for energy/glucose/oxygen increases
Define circulatory system
the transport system of an organism
Define open circulatory system
a transport system with a heart but with few vessels to contain the transport medium
Define closed circulatory system
the transport medium is enclosed in vessels and does not come into contact with the cells of the body
Define haemolymph
the blood like fluid contained in insects
Give examples of organisms with a single closed circulatory system
Fish and annelid worms
Give examples of organisms with a double closed circulatory system
Birds and most mammals
Give an example of an organism with an open circulatory system
Insects
Why are fish able to be highly active despite having a single closed circulatory system?
-the countercurrent exchange mechanism means they can take up a lot of O2 from water
-their body weight is supported by the water
-they do not maintain their own body temperatures
Why are single closed circulatory systems not very efficient?
Blood pressure drops considerably
so blood flows slowly back to the heart
Why are double closed circulatory systems very efficient?
-each circuit passes through only one capillary network
-this maintains relatively high blood pressure
-so fast flow of blood back to the heart is maintained
What are the general features of circulatory systems?
-fluid to transport dissolved gases, nutrients, and waste
-a pumping mechanism to move fluid
-sometimes vessels to carry the fluid
