Blood Components and Structure

When you spin blood in a centrifuge, it separates into three distinct layers that reveal its composition. Plasma makes up 55% of your blood and appears as a straw-coloured liquid containing water, proteins, glucose, amino acids, and salts.

The buffy coat sits in the middle, containing leukocytes (white blood cells) and platelets, making up less than 1% of total blood volume. At the bottom, erythrocytes (red blood cells) form 45% of blood volume.

Red blood cells are biconcave disks without a nucleus but packed with haemoglobin for oxygen transport. White blood cells are larger with prominent nuclei and come in different types for immune defence. Platelets are tiny cell fragments produced in bone marrow that enable blood clotting.

Quick Tip: Remember the percentages - plasma 55%, red cells 45%, everything else less than 1%!

Blood Functions

Blood performs four essential functions that keep your body working perfectly. Transport involves haemoglobin carrying oxygen and carbon dioxide, whilst lipoproteins move fats around your body - LDL causes fatty build-up but HDL prevents it.

Temperature regulation maintains your body at 37°C through vasodilation and vasoconstriction. This matters because enzymes stop working properly at higher or lower temperatures.

Exchange of materials happens in capillaries, which are only one cell thick. This allows nutrients and gases to pass in and out of body tissues efficiently. Finally, blood clotting occurs when platelets trigger coagulation, changing soluble proteins into insoluble clots when exposed to air or foreign materials.