we talked about transport systems today.. in particular.. blood.
normal people on average have around 5L of blood.
blood is around 45% blood cells and 55% plasma methinks, and 90% of that plasma is water.. the rest is anything random at all in your body that oculd be floating around in the blood.
blood is produced in the bone marrow, and is replaced every few weeks or so by new blood.
blood consists of 3 main types of cells.
RED BLOOD CELLS (around 7 million in 1mL)
- used to carry oxygen to cells.
- red substance haemoglobin attaches oxygen, becoming oxyhaemoglobin
- mature red blood cells have no nucleus
- they are disc shaped, thicker around the outside
WHITE BLOOD CELLS (around 4000 in 1mL)
- soldiers of body, produce antibodies
- fight of disease by engulfing them
- bigger than red cells, and are spherical
- sick people, or diseased people tend to have more white blood cells, particularly leukaemia
PLATELETS (around 40000 in 1mL)
- formed from cell fragments
- clot blood when exposed to air
- clotting prevents us from bleeding to death
- platelets can clot in long air travel, new disease
- much smaller than red or white cells
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