Download Mass transport TOJ

Exchange (3.3) includes:
 Surface area to volume ratio
 Gas Exchange
 Digestion and Absorption
 Mass transport
Homework booklets need to be taken seriously!
You should be able to:
Understand what is meant by a transport system,
and explain why it is needed in large animals.
 Describe the structure of the mammalian
transport system.
 Explain the need for a double pump in the
mammalian transport system.

How does
this amoeba
get the
substances
its needs to
live?
DIFFUSION
PHAGOCYTOSIS
Why can’t we get the substances we
need in these ways?
 Mammals
consist of millions of cells, which
all need maintaining (supply of substances
and removal of waste).
 The surface area available (relatively low
surface area: volume ratio)is not enough to
provide for all those cells and their high
energy needs.
How has this problem
been solved?
Exchange surfaces and
transport systems.
A mass transport system enables substances to be
taken in bulk between the cells and the specialised
exchange surfaces (e.g. alveoli in lungs).
Multi-cellular animals overcome the limitations of
diffusion by having a specialized circulatory system.
This comprises:

a heart

a fluid in which substances are transported

vessels through which the fluid can flow.
The two types of circulatory
system are open (e.g. molluscs,
arthropods) and closed (e.g.
vertebrates, a few invertebrates).
Exchange surface
Surface area to volume ratio
Diffusion
Can you add examples?
Described as a
closed, double
pump system.
Why?
In a closed circulatory system, blood is fully enclosed
within blood vessels at all times.
From the heart, blood is
pumped through a series
of progressively smaller
vessels. In the smallest
vessels, capillaries,
substances diffuse in and
out of the blood and into
cells.
heart
capillaries
Blood then returns to the heart via a series of progressively
larger vessels.
The heart is a muscular
organ located between the
lungs in the centre of the
chest (thorax), and is about
the size of a fist.
It pumps blood continuously
around the body. An organism
can lose consciousness within
just a few seconds if the brain
is deprived of blood.
In foetuses, the heart begins
beating about 5–6 weeks after
conception.
What do you already know about the structure?
The chambers of the heart are separated by valves
which prevent blood from flowing in the wrong direction.
Semilunar valve
Atrioventricular
valve
Semilunar valve
Atrioventricular
valve
There are valves between the atria and the ventricles…
…and there are valves leading out of the ventricles.
The valves between the atria and ventricles are connected
to the inner walls of the heart by tough tendons.
valve open
The tendons allow the valves to close and hold the valve
flaps in place. They prevent the valves from flipping up
and turning inside out. Why is this important?
valve open
valve closed
Name the blood vessel in each of the
following descriptions:
1.
2.
3.
4.
5.
Joins the right ventricle to the capillaries
of the lungs pulmonary artery
Carries oxygenated blood away from the
heart aorta
Carries deoxygenated blood away from
the liver hepatic vein
The first main blood vessel that an
oxygen molecule reaches after being
absorbed from an alveolus pulmonary
vein
Has the highest blood pressure aorta