Blood Cells
Biology: Cambridge International A Level, topic 8.1.4
Blood Cells
Blood is the liquid that moves through the vessels and includes plasma (the liquid portion), red & white blood cells, and cell fragments called platelets.
Components of blood
- Blood plasma is the dominant component of blood. It contains water, proteins, electrolytes, lipids, and glucose.
- The cells are responsible for carrying the gases (red cells) and the immune response (white).
- The platelets are responsible for blood clotting.
- Tissue fluid that surrounds cells is separate from the blood. Tissue fluid is drained via the lymphatic system.
Red blood cells
- Red blood cells (erythrocytes) are specialized cells that circulate through the body delivering oxygen to cells.
- They contain haemaglobin, which binds to oxygen.
- Red blood cells are smaller than almost all white blood cells and have a biconcave shape. They have no nucleus.
White blood cells
- White blood cells primarily involved in the immune response to identify and target pathogens.
- White blood cells have nuclei and do not contain haemoglobin.
- White blood cells include neutrophils, lymphocytes, & monocytes.
- **Neutrophils **are characterized by a lobed nucleus and granular inclusions in the cytoplasm. They are typically first-responders during injury or infection.
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White blood cells - 2
- Lymphocytes, including B and T cells, are responsible for the adaptive immune response.
- B cells differentiate into plasma cells. Plasma cells make antibodies. This process requires help from T cells.
- Lymphocytes have a large nucleus that takes up most of the cytoplasm.
- Monocytes differentiate into macrophages, which in turn respond to infection or injury.
- Macrophages phagocytose invading pathogens. They are larger than lymphocytes.
Test yourself on Blood Cells
Which of the following has a granular cytoplasm?