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Lymphatic system
| Question | Answer |
|---|---|
| Lymphatic system | the body system that transports excess fluid away from the tissues back to the circulatory system |
| Two main functions | Drain excess fluid from the tissue bed & return it to the circulatory system Plays a role in internal defence against disease causing organisms (pathogens) |
| Drain excess fluid from the tissue bed & return it to the circulatory system | Body fluid 55-60% of body ⅔ intracellular (inside cells) ⅓ extracellular fluid (outside cell) - Tissue fluid (interstitial/ intercellular) - Fluid that fills the microscopic spaces between cells Blood plasma |
| Main structures | Lymph Lymph capillaries Lymph vessels Lymph node |
| Lymph | colourless fluid that circulates through lymphatic vessels before returning to the heart |
| Lymph capillaries | blind-ended tubes between the cells of most tissues Slightly large than blood capillaries & more permable so proteins & disease causing organisms can easily pass through walls into the lymph |
| Lymph vessels | a network of lymph capillaries that have joined together Structurally similar to veins Lined by layer of endothelial cells Thin layer of smooth muscle Have valves to prevent back flow of lymph, |
| Lymph node | a small bean-shaped organ that filters substances into your body Located along the lymphatic vessels at intervals Mostly in neck armpit groin & alimentary canal |
| Lymph node structure | Bean shaped (1mm-25mm) Capsule of connective tissue Within are masses of lymphoid tissue that contain Lymphocytes (B&T cells) Macrophages (phagocytes) Criss cross of mesh fibers |
| Lymph movement | occurs despite low pressure due to the smooth muscle action, valves & compression during contraction of adjacent skeletal muscles |
| Connection to the circulatory system | The lymphatic vessels join up into larger vessels which join into 2 large ducts Thoracic duct Right lymphatic duct These ducts empty their contents into the subclavian veins (bring back to heart) |
| lymph node filter | Bacteria are trapped in the mesh & attacked by macrophages via phagocytosis When infection occurs the formation of lymphocytes (white blood cells) increases & lymph nodes become swollen |
Created by:
procrast
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