13.5 Circulatory System of a Mammal
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Transcript 13.5 Circulatory System of a Mammal
Circulatory System of a Mammal
13.5
13.5 Circulatory System of a Mammal
Learning Objectives:
Over large distances, efficient supply of materials is
provided by mass transport.
The general pattern of blood circulation in a
mammal.
(Names are required only of the coronary arteries
and of blood vessels entering and leaving the heart,
liver and kidneys).
Mass Transport – Why is it needed?
Diffusion is adequate for transport over small distances.
Efficient supply of materials over larger distances requires a mass
transport system.
With increasing size, and decreasing surface area to volume ratio, the
needs of the organism cannot be met by use of the body surface alone.
Specialised exchange surfaces are located in specific regions of the
body to allow absorption of nutrients and respiratory gases and the
excretion of waste substances.
Materials need to then be transported from the exchange sites to other
areas of the body, and to the external environment.
Factors determining the presence of
mass transport
The surface area to volume ratio
The activity of the organism
Obviously, the greater the activity and smaller the ratio, the
greater the need for mass transport and a pump.
Features of Transport Systems
Internal Medium to carry substances (must be able to dissolve
some substances)
A closed system of tubular vessels with a branched network
allowing supply to all areas of organism
A mechanism for moving the internal medium within the vessels:
a pressure difference between different part of the system. This is
achieved by either :
a pumping mechanism – muscles or organ such as heart
A passive process, eg evaporation of water
A mechanism to maintain mass flow in one direction eg ?
A means of controlling the flow to suit the needs of the organism
The Heart
11
Pulmonary artery
9
Semi-lunar valve
7
Aorta
2
Pulmonary vein
Vena cava
10
8
1
3
Right atrium
4
Bicuspid
valve
Tricuspid valve
5
6
Left atrium
Right ventricle
Left ventricle
Mammalian Double Circulatory System
Mammalian Double Circulatory System
Questions
What does a ‘double’ circulatory system mean?
Blood passes twice through the heart for each circuit of the body.
Why is it advantageous/necessary?
When blood passes through the lungs, the pressure lowers. If it
didn’t go back to the heart before going off to the body, then
circulation would be very slow.
Having a double circulation boosts pressure and helps to deliver
substances to the rest of the body quickly (which is needed due to
mammals having a high body temperature and a high metabolism)
Task
Complete Summary Questions on page 185.
13.5 Circulatory System of a Mammal
Learning Objectives:
Over large distances, efficient supply of materials is
provided by mass transport.
The general pattern of blood circulation in a
mammal.
(Names are required only of the coronary arteries
and of blood vessels entering and leaving the heart,
liver and kidneys).