Human Body's First Line of Defense: Physical, Chemical, and Cellular Barriers
Classified in Biology
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1) Physical Barriers Against Infection
Physical barriers are crucial in preventing microbes from reaching susceptible tissues.
Cellular Contributions to Physical Barriers
At the cellular level, tightly joined cells form barriers, preventing invaders from penetrating deeper tissues.
Microbial Evasion of Physical Barriers
Pathogens may use enzymes like proteases to damage physical barriers and gain entry.
2) Layers of Human Skin
Human skin has three layers:
1. Epidermis: Outer layer containing keratin (prevents microbial entry).
2. Dermis: Middle layer with hair follicles, sweat glands, nerves, and blood vessels.
3. Hypodermis: Inner layer with fatty tissue, blood, and lymph vessels.
Significance of Keratin, Fatty Acids, and Skin Shedding
- Keratin: Tough,