External defense mechanisms include:
- Skin
- Covered by a dead layer of cells (cornified layer).
- Water-proof, germ-proof, and self-repairing.
- Secretes sebum, which kills bacteria and keeps the skin moist.
- Mucus
- Found in the lining of the respiratory and digestive tracts.
- Traps bacteria, germs, and dust.
- Cilia carry trapped particles to the gullet.
- Tears
- Moistens and cleans the eye.
- Washes out germs, dust, and foreign objects.
- Blinks to prevent entry of substances.
- Acid in the Stomach
- Kills swallowed germs.
- Enzymes digest these killed germs.
- Blood Clotting
- Blocks blood loss and prevents microorganisms from entering through cuts.
- Involves platelets and the enzyme thrombin.
- Vaginal Secretions
- Slightly acidic (after the onset of menses).
- Secretes acids that destroy and prevent the entry of microorganisms.
- Ear Wax
- Traps dust or solid particles in the ear canal.
- Prevents particles from reaching the eardrum.
- Cilia
- Hair-like structures in the epithelial lining of the trachea and bronchi.
- Move to expel foreign material from the trachea.
- Symbiotic Defense
- Bacteria in the alimentary canal feed on other microorganisms and secrete vitamin K.
- Overgrowth of bacteria like E. coli can lead to infection.
Internal Defense Mechanisms
- Performed by the body’s immune system.
- Recognizes and destroys foreign bodies.
- Involves cells such as basophils, neutrophils, eosinophils, and lymphocytes.
Side Effects of Organ Transplant
- Lowered Immunity: Due to the use of immunosuppressive drugs.
- Opportunistic Infections: Increased risk of infections at the transplant site.
- Allergic Reactions: Possible hypersensitivity reactions making the patient uncomfortable as the transplant integrates.