Download Composition of Blood

3.2 ORGANISATION AND THE VASCULAR STRUCTURES
3.2.2 Organisational Complexity of the Human Cont’d
Composition of blood, role of red blood cells, white blood cells, platelets and plasma
Composition of blood
Blood is made of plasma and suspended solids – red blood cells, white blood cells and platelets.
Plasma
Plasma is the liquid part of the blood. It is a pale yellow liquid and is 55% of the blood.
Role of plasma
1. Transports useful substances - glucose, amino acids
2. Transports wastes – salts, urea, CO2
3. Transports hormones
4. Transports heat
Serum is plasma without the clotting proteins.
Red Blood Cells (Erythrocytes)
Red blood cells
 are made in the bone marrow of breastbone, ribs and vertebrae
 are round and very small
 are flexible and have a biconcave shape
 contain a red globular protein or pigment called haemoglobin
Flexible
membrane
Role of red blood cells
Biconcave
Red blood cells transport oxygen
Ms. B. Fennessy
Loreto Secondary School
Fermoy
Co. Cork
3.2 ORGANISATION AND THE VASCULAR STRUCTURES
White Blood Cells (Leucocytes)
White blood cells
 are made in the bone marrow (some mature in the thymus gland)
 are larger than red blood cells
 have no definite shape
 are colourless
Role of white blood cells
White blood cells fight infection
Platelets (Thromocytes)
Platelets
 are made in the bone marrow
 are cell fragments
 have no nuclei
Role of platelets
Platelets help to clot the blood
Ms. B. Fennessy
Loreto Secondary School
Fermoy
Co. Cork
3.2 ORGANISATION AND THE VASCULAR STRUCTURES
H.3.2.3 Blood Cells (Extended Study)
More detailed treatment of red blood cells – e.g. absence of nucleus, absence of mitochondria.
Mature red blood cells have no nucleus. (The nucleus dies a few days after the cell is formed – this is
why they can be called corpuscles).
Red blood cells have no mitochondria.
The fact that red blood cells have a biconcave shape means that they have a larger surface area for
carrying oxygen. The oxygen combines with the iron containing haemoglobin (dull red)to form oxyhaemoglobin (bright red).
Haemoglobin + O2
(dull red)

Oxyhaemoglobin
(bright red)
Red bloods get damaged due to always squeezing through narrow blood vessels (capillaries).
They cannot repair themselves and only live for about 4 months.
Dead red blood cells are broken down in the liver and spleen. The iron is recycled to make new
haemoglobin and the rest of the cell is changed into bile pigments.
Flexible
membrane
Biconcave
More detailed treatment of white blood cells – classification as lymphocytes and monocytes.
There are 2 main types of blood cells
Remember!
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Ms. B. Fennessy
Loreto Secondary School
Fermoy
Co. Cork
3.2 ORGANISATION AND THE VASCULAR STRUCTURES
Monocytes
Monocytes (macrophages) are the biggest type of white blood cell.
They are made in the bone marrow. They have large, kidney-shaped nuclei. They can move around
the body and act as scavengers by engulfing bacteria. Therefore, they are phagocytes.
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Lymphocytes
There are different types of lymphocytes.
They are made in the bone marrow (some mature in the thymus gland) and they are stored in the
lymph nodes, tonsils and adenoids (lymphatic system).
They have a large round nucleus that almost fills the entire cell. The main function of lymphocytes is to
make antibodies.
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Ms. B. Fennessy
Loreto Secondary School
Fermoy
Co. Cork
3.2 ORGANISATION AND THE VASCULAR STRUCTURES
Blood grouping
Names of the common blood groups A, B, AB, O and the Rhesus factors.
Red blood cells have chemicals on the surface of their cell membranes. These chemicals are called
antigens.
Remember!
The immune response is being able to recognise ‘foreign’ chemicals and
non-self cells due to their antigens and then make chemicals called
antibodies that repel the invasion.
An antigen is a foreign molecule that stimulates the production of antibodies
The two main antigens that could be on a red blood cell are Antigen A and Antigen B.
Your blood group depends on whether you have these antigens (or not) on the surface of your red blood
cells.
Blood Group
Antigens present
A
Antigen A
B
Antigen B
AB
Antigen A and Antigen B
None
O
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Notice Blood Type O has no antigens so it will not stimulate the production of antibodies in another
person, it can be given to anyone. It is the Universal Donor.
Ms. B. Fennessy
Loreto Secondary School
Fermoy
Co. Cork
3.2 ORGANISATION AND THE VASCULAR STRUCTURES
Rhesus Factor
The rhesus factor is another antigen that might be on the surface of red blood cells.


Red blood cells that have the Rhesus Factor are rhesus positive (Rh+)
Red blood cells that do not have the Rhesus Factor are rhesus negative (Rh-).
Blood Group
Antigens present
A+
A positive
Antigen A
Rhesus Factor
AB+
AB positive
Antigen A
Antigen B
Rhesus Factor
OO negative
None
Importance of Blood Groups

Blood groups are important when giving blood transfusions.
If blood groups are wrongly mixed the person being given the blood could make antibodies that would
react with the antigens in the donated blood. This would cause the blood to clump or agglutinate and
the person could die

Blood groups are important during pregnancy.
If a mother is Rh- and her baby is Rh+ (has the Rhesus Factor) then the mother will
make antibodies against this antigen. This Rhesus incompatibility will not affect
the first baby but the next baby will be affected by the mother’s antibodies and
would be anaemic or seriously harmed.
Ms. B. Fennessy
Loreto Secondary School
Fermoy
Co. Cork
3.2 ORGANISATION AND THE VASCULAR STRUCTURES
3.2.2 Organisational Complexity of the Human
Organisational complexity of the human.
The circulatory system: description of the
structures and organisation of tissues in the
closed circulatory system in humans, strong
muscular heart and vessels (arteries, veins,
capillaries, venules, arterioles).
Role of muscle tissues and valves.
Two-circuit circulatory system.
O
rganisational complexity of animals as exemplified by the
circulatory structures of the human system by brief reference to the
efficiency of a closed circulatory system in humans.
Describe the structures and organisation of tissues in the closed
circulatory system in humans.
The strong muscular heart in which the atria receive blood and the
muscular ventricles pump the blood through the vessels.
Vessels of the human circulatory system. Draw, label and give the
functions of the artery, vein and capillary. Refer to the existence and
position of arterioles and venules – the role of muscle tissue and valves
in the heart and circulatory tissues.
Ms. B. Fennessy
Loreto Secondary School
Fermoy
Co. Cork