Transport In Humans: Blood
11.4 Blood
Components Of Blood
| Component | Function |
|---|---|
| Red blood cells (RBCs) | Transport oxygen (contain haemoglobin, no nucleus, biconcave shape increases surface area) |
| White blood cells (WBCs) | Defence against disease: Lymphocytes (antibody production), Phagocytes (engulf pathogens) |
| Platelets | Clotting → convert fibrinogen to fibrin, prevent blood loss & entry of pathogens |
| Plasma | Transport medium: carries blood cells, ions, glucose, amino acids, urea, COâ‚‚, hormones, proteins, vitamins |
Red Blood Cells Adaptations
- Biconcave shape → large surface area for gas exchange.
- No nucleus → more space for haemoglobin.
- Flexible → squeeze through capillaries.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course
White Blood Cells
- Lymphocytes:
- Produce specific antibodies to destroy pathogens.
- Each pathogen has unique antigens → antibodies bind to them.
- Phagocytes:
- Engulf and digest pathogens by phagocytosis.
- Non-specific defence.
Substance Exchange With Tissues
- Capillaries leak plasma → tissue fluid.
- Nutrients, oxygen pass into cells.
- Waste (COâ‚‚, urea) pass from cells into blood.
Key Points To Remember
- Platelets are fragments, not full cells.
- Plasma = liquid part of blood (mainly water).
- WBC count rises sharply during infection.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course