1. Microscope drawing of blood smear
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
Blood composition
Blood consists of a pale yellow fluid called plasma in which are suspended white blood cells, platelets and red cells.
Centrifuged whole blood
Microscope drawing of blood smear
white cells
red cells
plasma
white cells
red cells
If blood is centrifuged the cells precipitate leaving the plasma as a supernatant.
Here is a photograph of a blood smear taken down a microscope

2. Microscope drawing of blood smear
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
Blood composition
Can you label the arrows?
plasma
Microscope drawing of blood smear
Plasma transports:
Carbon dioxide from the organs to the lungs
Soluble products of digestion from the small intestine to other organs
Urea from the liver to the kidneys
Plasma contains a variety of dissolved solutes such as urea, glucose, hormones.
platelet
red blood cell
whiteblood cell
It also contains plasma proteins that remain in the blood all the time.

3. Microscope drawing of blood smear
IGCSE BIOLOGY – TRANSPORT
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
Blood composition
Microscope drawing of blood smear
white cells
White cells:
Have a nucleus
Form part of the body’s defence system against microbes

4. Microscope drawing of blood smear
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
Blood composition
Red cells
Have no nucleus
Microscope drawing of blood smear
Are packed with a red pigment called haemoglobin
In the lungs oxygen combines with haemoglobin to form oxyhaemoglobin
red cells
In other organ oxyhaemoglobin splits into haemoglobin +O2

5. Microscope drawing of blood smear
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
Blood composition
Design features of red blood cells for oxygen carriage
Microscope drawing of blood smear
No nucleus making more room for haemoglobin
Doughnut shaped giving greater surface area for gas exchange
red cells

6. II.7 ANIMAL TRANSPORT Platelets Blood composition
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
Blood composition
Platelets
Platelets are small fragments of cells
Platelets have no nucleus
Platelets help blood to clot at the site of a wound
platelets
Light microscope photograph of a stained blood sample (X3000) Platelets are stained blue

7. II.7 ANIMAL TRANSPORT White blood cells The immune system
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
The immune system
White blood cells
If pathogens gain entry to the body 2 types of white cells attack them:
lymphocyte
Makes antibodies which attach to the pathogen and help disable or destroy it
Produces antitoxins which neutralise any toxins produced by the pathogen
phagocyte
Phagocytic - engulfs the pathogen and digests it.
Microscope photo of a human blood smear

8. II.7 ANIMAL TRANSPORT White blood cells The immune system Phagocyte.
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
The immune system
White blood cells
– phagocytosis and antibody action
Pathogen engulfed by white cell
engulfs and digests pathogens by phagocytosis
Invading pathogens usually a bacteria or viruses
Phagocyte.
Pathogen toxin
produces antibodies to attack the pathogens or their toxins
Lymphoctye
Pathogen or toxins produced by the pathogen
antibody

9. II.7 ANIMAL TRANSPORT Re-infection The immune system
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
The immune system
Re-infection
Once they have produced antibodies against a particular bacterium or virus, white memory cells can produce them quicker, and in greater quantity if the pathogen returns, giving the person immunity against that disease
Memory cells: rapid and massive antibody production
Level of antibody in the blood
The pathogen is eliminated but the damaging symptoms of disease will have already occurred
The pathogen is eliminated before disease symptoms and dangers occur
Time
initial infection
infection over
new infection

10. II.7 ANIMAL TRANSPORT Vaccination The immune system
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
The immune system
Vaccination
Introducing a mild or dead form of the disease into a person causes the production of antibodies without the symptoms of disease
HOW VACCINATION WORKS
Memory cells: rapid and massive antibody production
Level of antibody in the blood
The pathogen is eliminated before disease symptoms and dangers occur
Antibodies produced but no disease symptoms
Time
Vaccination with mild or dead pathogen
Infection with the real virulent pathogen

11. II.7 ANIMAL TRANSPORT Blood clotting
IGCSE BIOLOGY – TRANSPORT
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
Blood clotting
When a blood vessel is damaged, either by a cut or other means, the blood clots for 2 reasons:
To prevent leakage of blood
To prevent the entry of pathogens
How clotting happens:
There is a protein called ___________ which circulated in the blood. At points of damage in blood vessels this protein is converted to _______, a net like protein which catches red blood cells and forms a tangle, or clot.
fibrinogen
A blood clot forming – the blood protein fibrin (white) acts like a net at the point of damage. It catches red blood cells and they form a clump which blocks the opening in the blood vessel
fibrin

12. II.7 ANIMAL TRANSPORT Blood clotting
IGCSE BIOLOGY – TRANSPORT
THE HEART
THE IMMUNE SYSTEM
II.7 ANIMAL TRANSPORT
CIRCULATORY SYSTEM
THE LYMPHATIC SYSTEM
BLOOD AND BLOOD CELLS
ROUND UP
Blood clotting
White blood cells move to the clot to kill bacteria of viruses entering through the point of damage
white blood cell
‘puss’ a mixture of fibrin and dead white blood cells
fibrin
trapped red blood cell

13. CLICK HERE TO RETURN TO THE CIRCULATORY SYSTEM
IGCSE BIOLOGY – TRANSPORT
II.7 ANIMAL TRANSPORT
CLICK HERE TO RETURN TO THE CIRCULATORY SYSTEM
William Harvey was born in England in In 1628 Harvey published An Anatomical Study of the Motion of the Heart and of the Blood in Animals which explained how blood was pumped from the heart throughout the body, then returned to the heart and recirculated. The views this book expressed were very controversial and lost Harvey many patients, but it became the basis for all modern research on the heart and blood vessels.

14. Immunity Types of immunity Natural active immunity
Immune system activation due to infection
Artificial active immunity (vaccination)
Immune system activation by vaccination
Artificial passive immunity
Injection with antibodies. Used against potentially fatal and fast acting diseases e.g. tetanus antitoxin
Natural passive immunity
Mother’s antibodies crossing the placenta e.g. measles. Also IgA in colostrum prevents bacterial / viral growth