1) Mammals require transport systems like the circulatory system to efficiently deliver oxygen and nutrients to cells throughout the body since diffusion is only effective over short distances. The circulatory system can be open, closed, or a double circulatory system. 2) In a closed circulatory system, blood remains within blood vessels and nutrients/gases are exchanged through vessel walls. A double circulatory system has two circuits - pulmonary and systemic - allowing blood to pass through the heart twice. 3) Diseases can occur if cholesterol builds up in artery walls, restricting blood flow and oxygen delivery. This can cause heart attacks, strokes, aneurysms, and high blood pressure. Proper diet, exercise, and managing

1. Transport Systems in
Mammals
Re-purposed by Trischa Pretorius

2. Why are Transport Systems
Needed?
• Many invertebrates rely on diffusion to
supply its cells with oxygen. However
diffusion is only efficient over short
distances.
• In large animals such as humans more
oxygen are required for respiration in our
muscles and so we need a more effective
way of delivering large quantities of
oxygen quickly – hence our circulatory
system.

3. The Types of Circulatory
System
Open Circulatory system
(as seen in insects)
Closed circulatory system
(as seen in worms)

4. Open Circulatory System
• In an open circulatory system the blood
enters and circulates in the interstitial
spaces (spaces between the tissues).
• The exchange of materials between the
cells and the blood is done directly.
• There are few blood vessels but they are
not extensive.
• The blood vessels are open-ended as
they open into the common cavities called
the haemocoel.

5. Closed Circulatory System
• In a closed circulatory system the blood
always remains inside the blood vessels and
never comes in direct contact with the cells.
• The materials enter and exit the blood vessels
through the walls.
• The blood flows in the blood vessels under
high pressure such that it reaches all the
parts of the body in good time.
• The blood vessels are branched into fine
capillaries which are actually involved in the
exchange of materials.

6. Double Circulatory System
• In a double circulatory system,
blood travels in two circuits around
the body.
• Pulmonary circuit: Deoxygenated
blood travels from the heart to the
lungs where it gains oxygen and
returns to the heart.
• Systemic circuit: Oxygenated
blood travels from the heart to all
parts of the body and back to the
heart

7. Blood passes through heart
TWICE per complete circuit

8. • Blood returning to
the heart is low in
oxygen and high in
carbon dioxide.
• This blood is said to
be deoxygenated.
• Blood leaving the
heart is high in
oxygen and low in
carbon dioxide
• This blood is said to
be oxygenated.
Oxygenated and deoxygenated
blood

9. Different types of blood
vessels
• Arteries
• Veins
• Capillaries

10. Arteries
• Arteries carries blood away from the
heart, and towards organs.
• Blood travels at high pressure and is
usually oxygenated.
• The artery has thick muscular walls to
withstand the high pressure.
• Some major arteries are:
 Aorta
 Pulmonary Artery
 Hepatic Artery
 Renal Artery

11. Veins
• Veins take blood to the heart and away from
organs.
• Blood travels at low pressure therefore
veins have valves to prevent blood going
backwards - if the blood goes backwards (i.e.
towards the valves) this will cause them to
close and thus preventing further movement.
• The blood inside veins is usually
deoxygenated.

12. Veins
• Some major veins are:
 Vena Cava
 Pulmonary Artery
 Hepatic Portal Vein
 Renal Vein

13. Capillaries
• Capillaries are
microscopic vessels
that connect arterioles
to venules.
• Walls are only 1 cell
thick and allow
substances to be
exchanged between
blood and body cells.

14. The Heart and Associated
Blood Vessels
• The heart consists of 4 chambers.
• The upper chambers receive blood
and are called atria.
• The lower chambers pump blood out
of the heart and are called
ventricles.
• There are valves situated between
the chambers and at the points
where blood leaves the heart.
• Valves are present to ensure that
blood only travels in one direction.

15. The Heart and Associated
Blood Vessels
• Between the atria and the ventricles are
atrioventricular valves, which prevent back-
flow of blood from the ventricles to the atria.
• The left valve has two flaps and is called the
bicuspid (or mitral) valve, while the right
valve has 3 flaps and is called the tricuspid
valve.
• The valves are held in place by valve tendons
(“heart strings”) attached to papillary
muscles, which contract at the same time as
the ventricles, holding the valves closed.

16. The Heart and Associated
Blood Vessels
There are also two
semi-lunar valves in
the arteries (the only
examples of valves in
arteries) called the
pulmonary and aortic
valves.
These valves prevent
the blood flowing
back to the ventricles.

17. When the blood reaches the alveoli,
oxygen diffuses into the blood and
carbon dioxide diffuses into the alveoli.
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Blood travels in the
pulmonary artery to the lungs.
The right ventricle contracts and forces
blood through the pulmonary valve.
Blood enters the right ventricle.
The right atrium contracts and forces
blood through the tricuspid valve.
Blood enters the right atrium.
Blood returns back to the heart
through the vena cava.
The Heart and Associated Blood Vessels

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When the blood reaches the
body cells, oxygen diffuses into the cells
and carbon dioxide diffuses into the
blood.
Blood travels in the
aorta to the body.
The left ventricle contracts and forces
blood through the aortic valve.
Blood enters the left ventricle.
The left atrium contracts and forces
blood through the bicuspid valve.
Blood enters the left atrium.
Blood returns back to the heart
through the pulmonary vein.
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The Heart and Associated Blood Vessels

19. The External Structure of the
Human Heart

20. The Internal Structure of the
Human Heart
(Bicuspid valve)

21. Blood Flow through the
Heart

22. Cardiac Cycle
• There is a sequence of events at each
heartbeat called the cardiac cycle.
• There are two phases – contraction
(systole) and relaxation (diastole).
Blood enters the atria from the veins.
• Contraction of the muscles of the atrial
wall forces blood into the ventricles.
• Blood is pumped out of the heart by
contraction of the ventricle muscles.

23. Cardiac Cycle
• Contraction of the atrial muscles is
called atrial systole.
• Contraction of the ventricular muscles
is called ventricular systole.
• Relaxation of the heart muscle is called
diastole.
• The pulse is a pressure wave caused by
contraction of the left ventricle.

24. Cardiac Cycle

25. Cardiac Cycle:
Electrocardiogram (ECG)
Electrodes are placed on the skin over opposite sides of the heart,
and the electrical potentials generated recorded with time. The
result is an ECG.
P wave = electrical activity during
atrial systole
QRS complex = electrical activity
during ventricular systole
T wave = ventricular repolaristion
(recovery of ventricular walls)
Q-T interval – contraction time
(ventricles contracting)
T-P interval – filling time – ventricles
relaxed and filling with blood

27. 3) The impulse is passed
from the AV node down the
bundle of His. The bundle of
His fibres as inside the
septum. They take the
electrical impulse down to the
apex of the heart. The bundle
of His fibres are insulated so
the ventricles don’t start to
contract.
4) The Purkinje fibres make
the left and right ventricles
contract. The electrical
impulses travel UP the Purkinje
fibres from the apex of the
heart. This makes the ventricles
contract from the apex of the
heart. This squeezes blood UP
and out of the heart.
2) The electrical impulse
reaches the AV node. The
AV node delays the
electrical impulse. This is to
give enough time for all of
the blood to move from the
atria into the ventricles.
1) The SA Node = ‘Pacemaker’
The SA node gives off an
electrical impulse that
causes the left and right
atrium to contract.
Controlling the cardiac cycle
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28. Summary of events during
the cardiac cycle

29. Lymphatic System
• Most tissue fluid is returned to the blood
plasma via the capillaries.
• Remaining tissue fluid enters the lymph
vessels – drain back into the veins close to the
heart.
• This fluid is now called lymph.
• Lymph nodes filter lymph and play an
important role in the body’s defence.

30. Lymphatic System

31. Diseases of the Heart and
Circulatory System
• Cardiovascular Diseases are caused by a build-up of
cholesterol fibres, dead muscle cells and
platelets on the inside of the coronary artery, called
an atheroma which reduces the flow of blood and
therefore oxygen to the tissues.

32. Diseases of the Heart and
Circulatory System
• If the atheroma breaks through the endothelium
(cells lining the inside of the artery) it forms a
rough surface that interrupts the smooth flow
of blood. This may result in formation of a blood
clot or thrombus.
• This is known as thrombosis.
The thrombus may block the
blood vessel reducing or
preventing blood supply to
the tissues (cardiac muscle).

33. Diseases of the Heart and
Circulatory System
• The plaque weakens the
wall of the artery. The
weakened points
swell to form a balloon-
like structure called an
aneurysm.
• If the wall is particularly
weak it may burst
causing a haemorrhage
or blood loss and possibly
death.

34. Diseases of the Heart and
Circulatory System
• Any cardiac cells that are supplied by
this blood vessel will be starved of
oxygen and glucose and therefore
cannot respire.
• These cells will die – this is called a
myocardial infarction or heart attack.

35. Diseases of the Heart and
Circulatory System
• A stroke occurs if an artery in the
brain bursts and blood leaks into the
brain tissue or when an artery supplying
the brain becomes blocked.
• The brain tissue becomes starved of
oxygen and dies. Strokes can be fatal
or very mild and may affect speech,
memory and control of the body.

36. Diseases of the Heart and
Circulatory System
• High blood pressure increases the risk of an
aneurysm and stimulates thickening of artery
walls, increasing the risk of thrombosis.
• Prolonged stress, diet and lack of exercise can all
increase blood pressure.
• High blood pressure increases the risk of heart
disease because:
 Higher pressure in arteries means the heart
has to work harder to pump blood into them –
therefore increases risk of failure.
 To resist higher pressure the walls of the
arteries thicken, which restricts the blood
flow.

37. Re-purposed from
Circulatory System of a Mammal. Retrieved 3 April, from
http://www.tes.co.uk/teaching-resource/Circulation-Blood-
Vessels-and-Tissue-Fluid-6070763/
Controlling the Heartbeat. Retrieved 3 April, from
http://www.tes.co.uk/teaching-resource/Controlling-the-
heartbeat-ELSS-Biology-6412761/
Heart and Heart Diseases. Retrieved 3 April, 2014, from
http://www.tes.co.uk/teaching-resource/AQA-3-1-5-AS-
Biology-Heart-and-amp-Heart-Diseases-6380648/
The Circulatory System. Retrieved 3 April, 2014, from
http://www.tes.co.uk/teaching-resource/The-Circulatory-
System-6345574/
Transport in Animals. Retrieved 3 April, 2014, from
http://www.tes.co.uk/teaching-resource/Transport-in-
Animals-6400934/