Describe the body defences, limited to: skin, hairs in the nose, mucus, stomach acid and white blood cells

The body has several defense mechanisms to protect against pathogens, including the skin, hairs in the nose, mucus, stomach acid, and white blood cells. Here’s a detailed description of each component:

1. Skin

• Barrier Function: The skin is the body’s largest organ and serves as a primary physical barrier against pathogens. It prevents the entry of bacteria, viruses, and other harmful microorganisms.
• Immune Response: The epidermis contains immune cells such as Langerhans cells and dendritic cells that detect and respond to pathogens. These cells can initiate an immune response if they encounter foreign invaders.
• Antimicrobial Properties: The skin produces antimicrobial peptides and maintains an acidic pH that inhibits the growth of many pathogens. Additionally, the presence of beneficial bacteria on the skin helps outcompete harmful microbes.

2. Hairs in the Nose

• Filtration: Nasal hairs (cilia) act as a natural filter, trapping dust, pollen, and other airborne particles that may carry pathogens. This prevents these particles from entering the respiratory system.
• Moisture and Temperature Regulation: The nasal hairs also help maintain humidity and regulate the temperature of inhaled air, which is important for optimal respiratory function.

3. Mucus

• Trapping Pathogens: Mucus is produced by goblet cells in the respiratory and gastrointestinal tracts. It acts as a sticky barrier that traps pathogens, dust, and other foreign particles.
• Transport Mechanism: Cilia lining the respiratory passages move mucus upwards towards the throat, where it can be swallowed or expelled, effectively removing trapped pathogens from the body.

4. Stomach Acid

• Chemical Barrier: The stomach secretes hydrochloric acid (HCl), creating a highly acidic environment (pH 1.5 to 3.5) that kills many ingested pathogens, including bacteria and viruses. This acidic environment is crucial for preventing infections from foodborne pathogens.

5. White Blood Cells

• Immune Defense: White blood cells (leukocytes) play a vital role in the immune system by identifying and destroying pathogens. Key types include:
  • Phagocytes (e.g., neutrophils and macrophages): These cells engulf and digest pathogens through a process called phagocytosis.
  • Lymphocytes (e.g., B cells and T cells): These are involved in adaptive immunity, producing antibodies specific to pathogens or directly attacking infected cells