Transport in Circulatory System notes

Notes created for OCR unit 1- all things circulatory.

HideShow resource information
  • Created by: Zoe
  • Created on: 15-05-12 11:10
Preview of Transport in Circulatory System notes

First 456 words of the document:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS
Small animals don't need a separate transport as the majority of things they need can be transported via
diffusion. However large animals do as diffusion would be to slow. Three main reasons why large
animals need a transport system are as followed:
Large animals have several layers of cells meaning O2 and nutrients wouldn't reach the deep
cells fast enough if the animal didn't have a transport system.
Larger animals have a small surface area: volume ratio which means it's not large enough to
supply all the oxygen and nutrients needed by the internal cells
Bigger animals have higher levels of activity; releasing energy which needs to replaced quickly,
only a transport system could do so ­ allowing a fast exchange of substances.
Good transport systems tend to have
Fluid to carry nutrients and oxygen around the body ­ in humans this is blood
A pump to create pressure ­ in humans this is the heart
Exchange surfaces that enable O2 to enter/exit the blood when it's needed.
Tubes/ vessels to carry the blood
2 circuits to pick up O2 and the other to deliver O2 to the tissues
SINGLE CIRCULATORY SYSTEMS
A single circulatory system is closed. Blood flows like a tide between the heart, body and gills then back
again. It's most commonly found in fish. There isn't a division of systemic and pulmonary like in a double
circulatory system.
ADVANTAGES ­ It doesn't waste energy.
DISADVANTAGES- it's at low pressure doesn't pump as fast. The oxygen rich and poor blood mix.
DOUBLE CIRCULATORY SYSTEM
A double circulatory system is closed. It has two routes. These are systemic (to the lungs) and pulmonary
(to the body) It goes through the heart twice ­ like having two pumps. The heart has four chambers.
Most vertebrates such as birds and humans have a double circulatory system.
ADVANTAGES- blood flow can be controlled by the heart. The pressure is high and is maintained.
Constant strong supplies, oxygen rich and oxygen poor blood are separated.
DISADVANTAGES ­ complex system with a danger of clotting, heart attack, failing valves, bleeding
out
OPEN CIRCULATORY SYSTEM
Fluid flows freely through the body cavity. It's found mainly in small animals such as ARACHNIDAS,
INSECTAS and CRUSTACEAE. It doesn't maintain pressure and provide much O2 but provide nutrients and
occasional O2. It has muscular pumping organs. Blood from the body enters the heart through pores
called OSTIA. The heart pumps blood to the head via PERISTALIS.

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS
ADVANTAGES- less vulnerable to pressure, have control over body temperature which allows them
to survive in extreme conditions ­ hot and cold. Less complex reducing risks of clotting and bleeding
out.
DISADVANTAGES- Low metabolic rates, it's also hard to rise and lower the velocity of blood flow.
CLOSED CIRCULATORY SYSTEM
The fluid is enclosed in tubes such as arteries and capillaries. The closed circulatory system has a pump. All
vertebrates have a closed circulatory system.…read more

Page 3

Preview of page 3

Here's a taster:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS
Each chamber of the heart has different muscle thicknesses.
Left Ventricle ­ This has thickest muscle. It's thicker Right Ventricle ­ Second thickest muscle. Thicker
than the right ventricle as it requires a powerful than the atria as it has to have an increased
contraction to force the blood around the whole contraction to pump the blood to the lungs. With
body at a high pressure. some pressure.…read more

Page 4

Preview of page 4

Here's a taster:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS
2) ATRIAL SYSTOLE
The heartbeat starts when the atria contract -both the right and left atria contract together. The
atria have a small contraction which forces blood into the ventricles through the already open
atrioventricular valves. This stretched the walls of the ventricles ensuring they are full of blood.
Contraction of the atria is known as atrial systole. Once the ventricles are full of blood, blood
flows back into the valve pockets causing them to snap shut.…read more

Page 5

Preview of page 5

Here's a taster:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS
When the ventricle is finished contracting, the heart muscle starts to relax, elastic tissues in the walls of
the ventricle start to recoil and the ventricle returns to its normal size. Pressure in the ventricle drops
very quickly ­ the pressure drops below the pressure in the major arteries so the semi-lunar valves close
due to the valve pockets been full of blood. This causes and "dub" sound. This also prevents any
backflow.…read more

Page 6

Preview of page 6

Here's a taster:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS
The AVN then holds "delays" the wave of excitation, before reacting. It does this to allow the ventricles
to full with blood and ensure the atria have finished contracting. The AVN then passes the wave of
excitation onto the bundle of his.
The Bundle of His is a group of muscle fibres responsible for passing the wave of excitation onto smaller,
finer muscle fibres in the right and left ventricle walls known as the purkyne fibres.…read more

Page 7

Preview of page 7

Here's a taster:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS
QRS wave = wave of excitation passing over the bundle of his and into the purkyne fibres. Here the
ventricle pressure is higher than the arteries so the semi lunar valves are forced open pushing blood
upwards.
T wave= electrical recovery before next impulse. Here the ventricle relaxes and recoils back to original
shape the semi-lunar valves close. The pressure in ventricle drops below that of atria so atrioventricular
valves open however the whole heart is still in diastole.…read more

Page 8

Preview of page 8

Here's a taster:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS
Carry blood back to the Very thin walls for
heart exchange of materials
At low pressure so walls such as oxygen
don't need to be thick Single layer of flattened
Large lumen to allow cells that reduce the
easy blood flow diffusion distance
Thinner layers of Lack of smooth muscle
collagen, smooth muscle and collagen makes
and elastic as they don't them not very strong
need to stretch and Narrow lumen allows the
recoil.…read more

Page 9

Preview of page 9

Here's a taster:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS…read more

Page 10

Preview of page 10

Here's a taster:

TRANSPORT IN ANIMALS- CIRCULATORY SYSTEMS…read more

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »