Blood consists of plasma, containing dissolved solutes, and a number of different types of cell, each with a specific function. Blood cells are made in the bone marrow.
Leucocytes are white blood cells.
White blood cells are involved in body defence. Fewer leucocytes than red blood cells. 72% are neutrophils (phagocytes), which engulf foreign proteins and pathogens; 24% are lymphocytes which produce antbodies.
- Biconcave disk
- Small and flexible shape
- No nucleus
- Packed with red pigment haemoglobin
- Transports oxygen and carbon dioxide in reversible reactions
- Has a large surface area over which gases (O2 and CO2) diffuse quickly
- Can easily change shape and squeeze through capillaries
- Small amounts of cytoplasm
- membrane with no nucleus.
Release blood clotting factors on damage
- Have small granules in cytoplasm
- Lobed nucleus
Engulf microbes by phagocytosis
- Very large nucleus
- Little cytoplasm
- B lymphoctyes
- T lymphocytes
- B lymphocytes produce antibodies
- T lymphocytes destroy infected cells and have other functions
- Large cells
- Bean shaped nucleus
Become macrophages after 3 days in blood system