3. COMPOSITION OF THE
BLOOD
THE PLASMA IS MADE UP OF:
1. 90% WATER
2. There are many substances dissolved in the
water,
e.g. Sugar, Protein, Hormones, Enzymes,
Minerals etc.
4. COMPOSITION OF THE
BLOOD
THERE ARE 3 TYPES OF CELLS SUSPENDED IN
THE PLASMA:
1. RED BLOOD CELLS
2. WHITE BLOOD CELLS
3. PLATELETS
5. Functions of the Blood
THE BLOOD HAS THREE MAIN FUNCTIONS:
1. TRANSPORT
2. FIGHTING INFECTION
3. CLOTTING
6. TRANSPORT:
The blood carries very many substances
around the body.
For example:
• Blood carries oxygen from the lungs to the
cells.
• Blood carries carbon dio0xide from the
cells to the lungs.
7. • Blood carries digested food products from the
intestines to the cells.
• Blood carries waste from the cells to the liver and
the kidneys.
• Blood carries hormones and enzymes around the
body.
9. CLOTTING:
• Sometimes a tear occurs in a blood vessel e.g.
when you are cut
• Blood will leak out
• Infection may enter
•It is vital that such tears are repaired quickly
•The blood does this by forming a clot that seals
the wound
10. • Another function of the blood is to help maintain
normal body temperature.
• THIS IS 37 C
11. • The function of red blood cells is to
carry oxygen around the body
Red blood cells
12. • The function of white blood cells is to
fight infection
13. • Some white blood cells produce substances called
antibodies that identify and destroy bacteria,
viruses
• Other white blood cells kill bacteria by engulfing
them and digesting.
14.
15. • The function of the platelets is to help the
blood to clot.
16. THE CIRCULATORY SYSTEM
• On leaving the heart, the blood passes into all of
the organs and limbs of the body before being
returned to the heart.
18. THE HEART
• The heart is located in the centre of the chest,
behind the breast bone.
• The function of the heart is to pump blood.
• The heart is made up of muscle called cardiac
muscle.
19. The Structure of the Heart
• The heart is divided into two sides, left and right,
separated by a wall of muscle called the septum.
• Each side has two chambers.
• The top chambers are called atria.
• The lower chambers are called ventricles.
21. The heart acts as if it were two
separate pumps:
1. The right ventricle pumps blood to the
lungs.
2. The left ventricle pumps blood all round
the rest of the body.
22. • Since the lungs are very close to the
heart, the right ventricle doesn`t
pump blood very far.
• Since it must pump blood much
further, the muscle of the left
ventricle is much thicker than of the
right ventricle.
24. THE HEART
• The Vena Cava carry deoxygenated blood
from all over the body to the right atrium.
• The Superior Vena Cava collect
deoxygenated from the upper parts of the
body.
• The Inferior Vena Cava collect the blood
from the lower parts of the body.
25. • The blood then flows into the right
ventricle.
• It is then pumped into pulmonary
artery.
26. • The Pulmonary Artery carries deoxygenated blood
from the right ventricle to the lungs.
• It divides in two, one to each lung.
• This blood is oxygenated in the lungs.
• The Pulmonary Veins carry oxygenated blood from the
lungs to the left atrium of the heart.
• There are four pulmonary veins, two from each lung.
Pulmonary Circulation
27. • The left ventricle contracts and pumps blood out
of the heart through the aorta.
• The aorta is the major artery of the body.
• It carries blood all over the body.
• It collects carbon dioxide.
• The deoxygenated blood travels back to the right
atria through the vena cava.
Systemic or General Circulation
28. Blood Flow Through the Heart
BLUE =
deoxygenated blood
RED =
oxygenated blood
Superior
Vena Cava
Inferior
Vena Cava
Pulmonary Veins
AortaPulmonary Artery
31. BLOOD VESSELS
• The tubes that carry blood are known as blood
vessels.
• There are three types:
Arteries
Veins
Capillaries
32. BLOOD VESSELS
• Arteries carry blood away from the heart.
• Veins carry blood towards the heart.
• Capillaries connect arteries to veins.
33. THE DIFFERENCES BETWEEN
ARTERIES AND VEINS
• The blood in the arteries is under much higher
pressure than in veins.
• This means that the wall of an artery is much
thicker than that of a vein.
• This also means that the passage through an
artery is much narrower than in a vein.
34.
35. THE DIFFERENCES BETWEEN
ARTERIES AND VEINS
• Arteries do not have valves because the blood
is under high pressure.
• To prevent low pressure blood flowing
backwards, veins have valves.
36.
37. THE DIFFERENCES BETWEEN
ARTERIES AND VEINS
• The blood in arteries is oxygenated
except for the pulmonary artery.
•The blood in veins is deoxygenated
except for the pulmonary vein.
38. Structure of Arteries
• They are thick-walled tubes. They all
have the same basic construction:
• A fibrous outer covering
• A middle layer of muscle and elastic
tissue
• An endothelial layer (a single layer of
flattened cells)
39. Structure of Capillaries
• The capillaries are the smallest blood
vessels.
• Their walls are one cell thick and
porous, thus allowing the passage og
gases and nutrients.
40. Structure of Veins
• They have three-layered walls similar
to that of arteries.
• Their walls are much thinner and the
lumen is larger.
• They have a fibrous outer coating
• A middle layer of muscle and elastic
tissue
• An endothelial layer
• They have valves to prevent the back
flow of blood.
41. THE HEARTBEAT
• When the heart pumps, a pulse of
blood is sent down the arteries.
• This pulse can be felt in several
places, e.g. the wrist, the temples
and the neck.
42. What is Pulse
• The rate at which your heart pumps
blood through your circulatory
system.
• When blood is pumped from the left
ventricle into the aorta, the aorta
swells.
• The elastic wall of the aorta contacts
thus forcing the blood to move on.
43. • This sets up a wave of swelling and
contracting which continues along all
the elastic tissues.
• It can be felt wherever an artery
passes close to the surface of the
skin and over a bone.
• Most adults heartbeat is 72 – 80
beats per minute.
• Babies have a beat of 130 times a
minute.
44. Anaemia
• Is a reduction in the bloods ability to
carry oxygen.
• It may be caused by :
Loss of blood,
Lack of iron in the diet,
A failure of the bone marrow to
produce the normal level of red blood
cells.
45. THE HEARTBEAT
• The normal human heartbeat is
seventy beats per minute.
• The normal human adult breathing
rate is 16-17 breaths per minute.
46. THE HEARTBEAT
• If more oxygen is needed by the muscles
and the brain the rate of the heartbeat
increases.
• Extra blood is pumped to these organs and
so they get extra oxygen.
• Carbon dioxide is also removed faster.
47. FACTORS THAT INCREASE THE RATE
OF THE HEARTBEAT INCLUDE:
• EXERCISE
• A FRIGHT
• SMOKING
• EXCITEMENT
