1
Q
why do animals have a heart and circulatory system
A
- to move substances around the body by mass flow as diffusion is to slow to support high metabolic rates in larger organisms
2
Q
mass flow
A
the transport of substance in bulk from one part of an organisms to another
3
Q
diffusion
A
the net movement of molecules or atoms from a region of high concentration to a region of low concentration until evenly distributed
4
Q
features of a mass flow system
A
- system of vessels
- valves
- high blood pressure
- transport medium of blood
5
Q
open circulatory system
A
- blood isn’t enclosed within blood vessels
- exchange of materials occurs in direct contact between blood and tissues
- low blood pressure
- found in small animals
6
Q
closed circulatory system
A
- blood is enclosed in blood vessels
- substances are exchanged in capillaries between blood and tissues
- high blood pressure
- found in large animals
7
Q
single circulatory system
A
- blood flows through the heart once
- systemic and pulmonary circulation are together
- heart has 2 chambers
- lower blood pressure
- e.g fish
8
Q
double circulatory system
A
- blood flows through the heart twice
- pulmonary and systemic circulation are separate
- heart has 4 chambers
- higher blood pressure
- e.g frogs, reptiles and mammals
9
Q
pulmonary circulation
A
- right ventricle - pulmonary artery - lungs - pulmonary vein - left atrium
- low pressure
10
Q
systemic circulation
A
- left ventricle - right atrium
- carries blood between heart and other organs except the lungs
- high pressue
