13 blood & circulation
TRANSCRIPT
1. What is the composition of blood?• Red blood cells (contain haemoglobin)
– Contain iron, which gives the red colour– Transports oxygen around the body
• White blood cells (many different types)– Fight disease, destroys foreign matter
• Platelets– Broken up blood cells– Forms clots to prevent excessive bleeding
when cut
• Plasma (55% of blood)– 90% water, but also waste (specifically
bicarbonate – dissolved CO2) and nutrients
2. How is blood carried?
Order of the blood vessels
The blood vessels
• Blood is carried from the heart via the aorta (primary artery) which splits in to:
• Arteries• Arterioles• Capillaries• In the various organs and tissues capillaries
exchange oxygen for carbon dioxide and nutrients for waste then return to the heart via:
• Venules• Veins• Superior & inferior vena cava (primary veins)
Arteries & arterioles
Capillaries• Oxygen in delivered to the cells of our
body via capillaries
Veins & Venules
Note the one-way valve
Peristalsis in veins & venules
• Blood leaves the heart via arteries and return via veins
• Almost all arteries carry oxygenated blood (exception: pulmonary artery)
• Almost all veins carry deoxygenated blood (exception: pulmonary vein)
Blood types – the ABO system• There are 4 blood types – A, B, AB & O• Each type of blood contains its own antigen• Each blood type has antibodies against the other
antigens
Blood type
A B AB O
Antigen A B AB -
Antibody B A - AB
Percentages of each blood type in the Australian population
Blood types – the ABO system• Antibodies are part of our defence system
and will clot and destroy its target antigen
• When blood is donated, it contains its own antigens but carries no antibodies
• If you have no antibodies, then you can receive any type of blood
• If your blood contains no antigens it can be given to anyone
Blood types – the Rhesus system
• The other main blood type is Rhesus (Rh), for this you can only be positive or negative.
• Rh+ carries the Rh antigen
• Rh- people produce the Rh antibody
Putting it all together
• So, we have a total of 8 blood types to consider when giving someone a transfusion:
• A+, A-, B+, B-, AB+, AB-, O+, O-
• Maintains body temperature by delivering heat from the liver to other parts of the body.
AB+ AB- A+ A- B+ B- O+ O-
AB+
AB-
A+
A-
B+
B-
O+
O-
AB+ AB- A+ A- B+ B- O+ O-
AB+
AB-
A+
A-
B+
B-
O+
O- X XXXXXX
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XX
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X
XX X X