pack 3- circulatory systems Flashcards
define diffusion
movement of molecules or ions from a high to low concentration down a concentration gradient
name the types of circulatory systems
open
single closed
double closed
describe an open circulatory system
simple heart pump blood into body cavity
substances diffuse in and out
when heart relax blood drawn back to heart
advanatages of a closed circulatory system
blood vessels allow blood to be carried faster at higher pressure delivering substances efficiently
capillaries allow close contact to all cells in the body for substance exchange
valves ensure blood flows in one direction
describe single circulatory system
heart pump deoxygenated blood to capillaries
gaseous exchange in capillaries
CO2 out O2 in
blood flow to body and return to heart
describe a double circulatory system
two chambers in heart
right ventricle pump deoxygenated blood to lungs to become oxygenated
left ventricle pump to rest of body
advantages of double circ system
heart gives blood ‘extra boost’
high metabolic rate
blood in lungs to maximise gas exchange
mass transport system- substances moved rapidly
define a mass transport system
body substances are moved through a transport medium
how many times does blood flow through heart- double circ
2
what organisms- double
birds and mammals
what organisms- single
fish
what organism-open
insects
