Blood cells, plasma and tissue fluid
Introduced| English | Meaning |
|---|---|
| plasma/ˈplæzmə/ | The liquid component of blood in which cells, proteins and other dissolved substances are carried. |
| tissue fluid/ˈtɪʃuː ˈfluːɪd/ | Fluid that leaks from capillaries and bathes the cells, supplying them and collecting waste. |
| monocyte/ˈmɒnəʊsaɪt/ | A white blood cell that can leave the blood and develop into tissue macrophages or related immune cells. |
| neutrophil/ˈnjuːtrəfɪl/ | A type of white blood cell that engulfs and destroys microorganisms and other foreign material. |
| lymphocyte/ˈlɪmfəsaɪt/ | A type of white blood cell involved in immune responses, including B cells and T cells. |
Blood, plasma 血浆 and tissue fluid 组织液
- Blood is mostly water carrying cells and dissolved substances.
- The liquid that leaks out to bathe your cells is tissue fluid.
- It is how every cell gets its oxygen and food.
The straw-coloured liquid part of blood, which carries the cells, is the ______.
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Plasma carries cells, dissolved nutrients, hormones and waste.
Blood cells
- Red blood cells carry oxygen (packed with haemoglobin, no nucleus).
- White blood cells defend the body — you should recognise:
- monocytes 单核细胞, neutrophils 中性粒细胞 (lobed nucleus), and lymphocytes 淋巴细胞.
A stained blood smear: small red cells and one larger white cell
The main job of a red blood cell is to:
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Red blood cells are packed with haemoglobin to carry oxygen; white cells handle defence.
Match each part of the blood to its job.
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Red cells carry oxygen, white cells defend, platelets clot, and plasma is the liquid that carries everything.
Why water is ideal
- Water is a good solvent, so it carries dissolved substances (glucose, ions, gases).
- Water has a high specific heat capacity, so the blood's temperature stays steady.
Tissue fluid
- At the start of a capillary, the high blood pressure pushes liquid out of the plasma — but not the cells or large proteins.
- This liquid around the cells is tissue fluid: it supplies oxygen and glucose and carries waste away.
- Most of it returns to the capillary at the far (venous) end, where the pressure is lower.
Tissue fluid forms at the arterial end and returns at the venous end
How tissue fluid forms
Step through it. High pressure pushes plasma out at the start of a capillary; most is drawn back at the far end.
Tissue fluid forms because:
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High hydrostatic pressure forces liquid out of the plasma; cells and large proteins are too big to leave.
Most tissue fluid returns to the capillary at the far (venous) end, where the pressure is lower.
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By the venous end the hydrostatic pressure has dropped, so the fluid is drawn back in by osmosis.
Put the formation and return of tissue fluid in order.
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Out at the arterial end → exchange → back at the venous end → excess into the lymph.
You've got it
- red blood cells carry oxygen; white cells (monocytes, neutrophils, lymphocytes) defend
- water = good solvent + high specific heat capacity (steady temperature)
- tissue fluid = plasma pushed out by high pressure (no cells/large proteins) to bathe cells
- most tissue fluid returns at the low-pressure (venous) end