1. The red blood cell is present in a vein which will carry it back to the heart. 2. It will enter the right atrium of the heart. 3. From the right atrium, the blood cell will enter the right ventricle when it contracts. 4. The right ventricle will pump the blood into the pulmonary artery which will carry it to the lungs. 5. In the lungs, the blood cell will release carbon dioxide and pick up oxygen. 6. It will then return to the left atrium of the heart via the pulmonary vein to complete the double circulation.

2. BLOOD
What percent of the
human body is blood?
How much blood do we
contain?
On average 4-6 liters
8%

3. COMPOSITION OF BLOOD
 Blood consists of a :
Liquid component:
PLASMA
Solid component:
BLOOD CELLS

4. How much is there of each
component?

5. Plasma can be separated
from the blood cells. How?
Centrifugation
plasma

6. Plasma is a clear,
yellow fluid
Percentage of water
in plasma :
Substances dissolved in
plasma:
 Glucose
 Amino acids
 Vitamins
 Minerals
 Lactic acid
Layering of blood
components in a
centrifuged blood
sample.
90%
 Hormones
 Urea
 Respiratory gases
 Antibodies
 Proteins

7. Question: MAY, 2010
Name the liquid component of blood and list
TWO substances dissolved in it. (3)
Amino acids
Glucose
[any two from
previous list.
FOOD is wrong]
PLASMA

8. Function of plasma:
to provide a medium through which continual
exchange between cells and blood takes place
Blood flow
Body cells

9. Three types of blood
cells:
a) ERYTHROCYTES or red
blood cells
b) LEUCOCYTES or white
blood cells
c) PLATELETS or
thrombocytes
Leucocytes
& platelets
Erythrocytes
Plasma

10. Red blood cells (RBC) are
formed in the red bone
marrow of the:
Ribs
Sternum
Vertebrae

11. RBC are:
 very small and numerous
 disc-shaped (BICONCAVE)
without a nucleus
 contain the red pigment HAEMOGLOBIN
 function of RBC:
to transport oxygen & some carbon dioxide

12. About 2 million RBC per second
are made but production is
faster at high altitude. Why?
There is not so much oxygen in the air.

13. Average life span of a RBC: 120
days
 the old and worn out RBC are broken down
in the:
liver
spleen

14. What forms from the
haemoglobin broken down?
 IRON part: stored in liver
 The rest of the haemoglobin molecule forms
BILE PIGMENTS
 bile pigments are
excreted in bile
Gall bladder
stores bile

15. Red blood cells are
adapted to carry
oxygen:
1. biconcave disc shape offers maximum
surface area for oxygen uptake
2. haemoglobin has a high AFFINITY for oxygen
and combines with it, forming
OXYHAEMOGLOBIN
3. no nucleus = more space for haemoglobin
4. being small makes it possible for oxygen to
enter and leave the RBC quickly

16. Deoxygenated
blood:
Deep red-purple
Oxygenated
blood: Bright red

17. Fig. 3 Role of haemoglobin.

18. Carbon monoxide combines more
readily with haemoglobin than
oxygen does
RBC do not carry oxygen to the cells Result:

19. WHITE BLOOD CELLS (WBC)
 are less
numerous
than RBC
 some live for
months
 most just a
few days

20. Two types of WBC:
 function of WBC:
to protect the body against microbes
LYMPHOCYTE PHAGOCYTE
Lobed
nucleus
Spherical
nucleus

21. Question: SEP, 2011
Draw a labelled diagram of:
i) a red blood cell as seen in section; (2)
ii) a white blood cell that engulfs and digests
harmful bacteria. (3)
Lobed nucleus
i) ii)Cell membrane
Cytoplasm Cell membrane
Cytoplasm

22. Phagocytes are adapted to
engulf bacteria by having:
 an irregular shape
 a lobed nucleus
Phagocytes can
squeeze out of
capillaries.

23. What is ‘inflammation’?
 phagocytes move to an infected area to attack the
microbes
 when this happens the area becomes:
 red
 swollen
 hot
INFLAMMATION
 pus may form
Pus = accumulation of WBC
+ microbes

24. Lymphocytes are produced in
the bone marrow :
 and then move into
the lymph nodes

25. Lymphocytes produce
antibodies in response to
antigens
 antibodies are :
 proteins
 specific
antigen: material
foreign to the body e.g.
a bacterium or virus

26. Antibodies begin the process of
destruction of the microbe and
phagocytes finish the job

27. Immunity is
 a natural resistance to infection due to
antibodies

28. Question: SEP, 2002
White blood cells fight microbes. The number
of white blood cells increases to eliminate the
pathogens. Phagocytes engulf and digest
harmful bacteria while lymphocytes produce
antibodies.
Briefly explain why the
presence of a large number
of white blood cells in a
blood sample, is an
indication of the presence of
an infectious disease. (3)

29. Platelets
 are cell fragments without a nucleus
 function :
important in blood
clotting

30. How does clotting take
place?
A clot begins to form when platelets
are damaged. Platelets release a
substance (thromboplastin /
thrombokinase).
Skin is cut.
A series of chemical reactions
occur that ends up by producing
a meshwork of FIBRIN.
1 2
3

31. Clot dries up to form a
scab

32. Blood
clottin
g

33. HAEMOPHILIA
is an inherited disease where a person’s
blood takes a very long time to clot
Blood clot formation needs a clotting
factor: missing in haemophiliacs.

34. FUNCTIONS OF THE BLOOD
TRANSPORT
PROTECTION
HOMEOSTASIS

35. SUMMARY OF THE BLOOD FUNCTIONS
 TRANSPORT
1. Oxygen from the lungs to the tissues.
2. Carbon dioxide from the tissues to the lungs.
3. Urea from the liver to the kidney.
4. Digested food from the small intestine to the
tissues.
5. Hormones from endocrine glands to target
organs.
6. Heat from tissues, especially the muscles to the
whole body.

36.  PROTECTION AGAINST MICROBES
1. By clotting it prevents fluid being lost from cuts
and wounds.
2. It protects against disease by killing microbes.
Phagocytosis

37.  HOMEOSTASIS - keeping a constant internal
environment by:
1. keeping a constant body temperature - by
spreading warmth evenly around the body
2. regulating the amounts of various substances in
the tissues

38. TYPES OF BLOOD VESSELS
Artery Vein
Capillary
Blood from
the heart.
Blood to
the heart.

39. Circulatory System
Veins
Carry blood towards the heart.
Venules
Capillaries join to form venules.
Blood Capillaries
Walls are one cell thick.
Partially permeable lining
allows substances to
diffuse quickly. Slow
movement of blood.
Heart
Relaxed state: heart is filled with
blood. Contracting heart: blood is
being pumped with great force out
to lungs and to rest of body.
Arteries
Artery carries blood away.
Arterioles
Branching of arteries.

40. What happens to an artery
when it enters an organ?
Branches into arterioles
and finally into capillaries.

41. Comparison of blood vessels
in structure
Arteries Veins Capillaries
1) Walls have a
thick muscle and
elastic layer
Walls have a thin
muscle and elastic
layer
Walls are one cell
thick

42. Capillaries are so thin that
RBC have to squeeze through

43. Arteries Veins Capillaries
2) No valves
present
Valves present to
prevent backflow
No valves
One-way flow

44. Explain the presence of valves in leg and arm
veins. (2)
Question: MAY, 2010

45. Explain the presence of valves in leg and arm
veins. (2)
Question: MAY, 2010
The contraction of muscles compressing
veins helps push blood up through the
leg and arm veins back to the heart.
The valves allow the blood to flow
towards the heart only.

46. Arteries Veins Capillaries
3) Fluid and WBC
cannot pass
through wall
Fluid and WBC
cannot pass
through wall
Fluid without
proteins can pass
through wall. WBC
pass out between
cells
artery vein
capillary

47. Veins act as blood
reservoirs

48. Question: MAY, 2010
Explain the wide lumen diameter and thin walls
in veins. (2)
Veins can store a large volume of blood inside
their wide lumen. Thin walls can easily extend to
contain the blood.

49. Comparison of blood vessels
in blood composition and
flow
Arteries Veins Capillaries
1) Flow is away
from the heart
Flow is towards
the heart
Flow is from
artery to vein
HEART

50. Arteries Veins Capillaries
2) Oxygenated
blood except
pulmonary artery
Deoxygenated
blood except
pulmonary vein
Mixed
Pulmonary artery
Vein
Artery

51. Question: SEP, 2012
List ONE function of the arterial
blood vessels (arteries). (2)
To supply oxygen to the body
cells.

52. Arteries Veins Capillaries
3) Rapid flow Slow flow
Very slow
flow
4) High pressure Low pressure Low pressure
5) Pulse strong No pulse No pulse

53. force exerted by circulating blood
on the walls of blood vessels
The pressure of the circulating blood decreases as
blood moves away from the heart
Blood Pressure refers to the:

54. TISSUE FLUID
 bathes the cells and keeps them in the right
condition
 forms from the blood HOW?

55. Tissue fluid forms at a capillary
bed under high blood pressure
Arterial flow
Venous flow
Lymphatic flow
As blood flows into
capillaries:
1. Tissue fluid forms.
2. Some tissue fluid
returns to the
blood.

56. EXCHANGE AT A CAPILLARY BED
 capillaries form a dense network in such a
way that every cell is close to a capillary
lymphatic vessel

57. tissue fluid
lymphatic vessel
Tissue fluid forms from
plasma. Lymph forms
from…………..
10% tissue fluid enters
lymphatic system
lymph
tissue
fluid
plasma

58. Two properties of the capillary network to allow
efficient exchange between the bloodstream & the
cells: 1. Large surface area of the capillary network
2. Being one cell thick

59. What happens to the lymph that
enters the lymphatic system?
Lymph empties into
subclavian veins.

60. The Lymphatic
System

61. Question: SEP, 2010
Give a biological explanation for each of the
following.
Tissue fluid forms from blood. (4)
Small molecules are forced out of the
capillary at the arterial end under high
blood pressure from the heart.

62. Comparison of blood plasma,
tissue fluid and lymph
Blood plasma Tissue fluid Lymph
LOCATION Inside blood vessels Bathing living cells
Inside lymph
vessels
Arterial flow
Lymphatic flow
Venous flow

63. Blood plasma Tissue fluid Lymph
COMPOSITION
Water, proteins,
glucose, salts,
hormones , amino
acids
Oxygen present
Very little protein,
otherwise similar
Oxygen present
More protein than
tissue fluid but less
than plasma. More
lipids, otherwise
similar.
No oxygen
CELLS RBC, WBC, platelets WBC WBC
TRANSPORT
Blood pressure
forces fluid through
capillary at the
arterial end.
Osmosis returns
fluid at the venous
end of the capillary
From capillary
under pressure
and return by
osmosis to
capillary (90%) and
10% to lymph
From tissue fluid
by drainage under
pressure

64. THE HEART
 the heart muscle:
 is called CARDIAC MUSCLE
 works without getting tired
 contracts automatically
CORONARY ARTERIES
supply the heart with
oxygenated blood.

65. Blocking of a blood vessel by
cholesterol
Blocked coronary
artery leads to a
heart attack
Dead muscle
tissue due to
lack of oxygen

66. Question:
Suggest TWO ways in which a person’s lifestyle
might lead to a blockage of the coronary
arteries.
1. Lack of exercise.
2. Smoking.
3. Eating food rich in fats.
4. Excessive alcohol intake.

67. What happens to the blood
pressure if a blood vessel is
blocked?
Normal blood flow
Abnormal
blood flow

68. The heart has four chambers
atria  Two upper chambers: atria / auricles
 Two lower chambers: ventricles
ventricles
A wall / septum separates the
two sides. Why?
To prevent mixing of deoxygenated
blood on the right side from the
oxygenated blood on the left.
RIGHT LEFT

69. Four valves in the heart
Tricuspid valve:
Prevents backflow
to right atrium
Bicuspid valve:
Prevents backflow
to left atrium
Semilunar valves:
Prevent backflow
to ventricles
RIGHT LEFT
Bicuspid valve
Tricuspid valve
Semilunar
valves

70. Parts of the heart
Atria:
Receiving Chambers
Ventricles:
Pumping Chambers
Valves:
Control Flow
Septum
Divides the Heart

71. Vertical section: the heart
Aorta
Pulmonary vein
Left atrium
Right atrium
Vena cava
Tricuspid
valve
Pulmonary artery
Right ventricle
Tendon Left ventricle
Semi-lunar valves
Bicuspid valve

72. Superior vena cava
brings blood from:
head & arms

73. The atria have thinner walls than
the ventricles
Thin-walled atrium
No need to build a high pressure as atria pump blood to
the ventricles just below them. Ventricles pump blood
further away so must have thicker walls to pump blood
at high pressure.
Thick-walled ventricle

74. Right ventricle has thinner
walls than left ventricle
Right ventricle pumps blood to lungs which are
near to heart but left ventricle pumps to whole
body. Thus less pressure is needed.
Right
ventricle
Left
ventricle

75. Question: SEP, 2010
Give a biological explanation for
each of the following.
Blood pressure is highest in the
arteries and lowest in the veins.
(4)
Highest blood pressure in arteries:
blood is pumped into them by
heart.
Lowest in veins: blood is far away
from heart.

76. What is a ‘stroke’?
 Interruption of oxygen supply to the brain
 Caused by:
A clot in an artery
in the brain
Breakage of an
artery in the brain
 Causes brain cells
to be deprived
of oxygen and die

77. It takes about 1 min. for blood to
make 1 complete cycle

78. Ventricles contract
Atria relax
Ventricles relax
Atria contract
When ventricles
contract blood
moves:
out of the heart
When atria contract
blood moves:
into the
ventricles

79. Are the ventricles
in systole or in
diastole?
Systole: contraction
Diastole: relaxation

80. Atria contract / Ventricles
relax

81. Ventricles contract / atria
relax

82. The events of the cardiac
cycle

83. Question: SEP, 2011
During exercise the heart pumps out a greater
volume of blood per minute than when the
body is at rest. List TWO ways in which the
heart can increase the volume of blood
pumped out. (4)
1. Increase in heart beat rate.
2. Each beat becomes stronger.

84. Double circulation: blood passes twice
through the heart for each circuit of the
body
Pulmonary circulation:
Heart-lungs-heart
Systemic circulation:
Heart-body-heart

85. Double
circulation is
found in:
 birds
 mammals

86. Pulmonary vein
Aorta
Hepatic artery
Renal arteryRenal vein
Hepatic
portal vein
Vena cava
Pulmonary
artery
Hepatic vein
The blood transport
system in humans

87. Question: SEP, 2007
A red blood cell is present in a
vein. Describe how the red blood
cell will reach the lungs. In your
answer mention the blood
vessels and the different
chambers of the heart that the
red blood cell must pass through.
(4)
The red blood cell present in a vein,
enters the vena cava. The vena cava
takes blood to the right atrium. Blood
is pumped into the right ventricle and
to the lungs via the pulmonary artery.

88. Question: SEP, 2007
Describe how a red blood cell in
the lungs reaches a kidney. In
your answer mention the blood
vessels and the different
chambers of the heart that the
red blood cell must pass through.
(5)
The red blood cell leaves the lungs via
the pulmonary vein and enters the left
atrium. The blood is pumped into the
left ventricle and out of the heart via
the aorta. The red blood cell enters the
kidney via the renal artery.

89. Question: MAY, 1998
Trace the path of a molecule of
glucose from the capillaries of the
small intestine to the brain. (5)
A molecule of glucose is absorbed by the blood
in the small intestine. It moves into the liver via
the hepatic portal vein and out of it through
the hepatic vein. Glucose enters the vena cava
which takes blood to the right atrium. Blood is
pumped into the right ventricle and to the
lungs via the pulmonary artery. Blood leaves
the lungs via the pulmonary vein and enters
the left atrium. The blood is pumped into the
left ventricle and out of the heart via the aorta.
The aorta branches into many arteries and one
such artery takes glucose to the brain.

90. Question: SEP, 2010
Give a biological explanation for each of the
following.
The hepatic portal vein links two organs. (4)
The liver is connected to the gut by the hepatic
portal vein. As soon as digested food is
absorbed into the blood, it goes to the liver.
The liver removes extra amino acids by
deamination and stores excess glucose as
glycogen. Thus the liver plays a role in
homeostasis.

91.  Explain why a baby born with a hole in its
heart tires very easily.
Deoxygenated blood from the right atrium flows into
the left atrium where it mixes with oxygenated blood.
The aorta carries this mixture to the muscles. The
muscles do not receive enough oxygen.
Adult heart Foetal heart

92. T H E
E N D