Question

Explain how the interplay between the skin and all other 1^st and 2^nd line non-specific immune defense mechanisms protect you from microbial invasion.​​

Answer 1

skin is the outemost and largest organ of the human body. it act as a barrier for infectious disease and antigen that will act as stimulus against the body.

non specific immune system is antigen independent and with maximum response to stimulus mechanism. in this system exposure results in no immunological memory.

The epithelial surfaces form a physical barrier that is very impermeable to most infectious agents. Thus, the skin acts as our first line of defense against invading organisms. The desquamation of skin epithelium also helps remove bacteria and other infectious agents that have adhered to the epithelial surfaces. Movement due to cilia or peristalsis helps to keep air passages and the gastrointestinal tract free from microorganisms. The flushing action of tears and saliva helps prevent infection of the eyes and mouth. The trapping effect of mucus that lines the respiratory and gastrointestinal tract helps protect the lungs and digestive systems from infection.

Fatty acids in sweat inhibit the growth of bacteria. Lysozyme and phospholipase found in tears, saliva and nasal secretions can breakdown the cell wall of bacteria and destabilize bacterial membranes. The low pH of sweat and gastric secretions prevents growth of bacteria. Defensins (low molecular weight proteins) found in the lung and gastrointestinal tract have antimicrobial activity. Sweat also contains low molecular weight anti-microbial peptides that interact with bacterial cell membranes (including MRSA) in which they form a channel that allows the passage of water and ions, disrupting the transmembrane potential, leading to the death of the cell.Surfactants in the lung act as opsonins (substances that promote phagocytosis of particles by phagocytic cells).
The normal flora of the skin and in the gastrointestinal tract can prevent the colonization of pathogenic bacteria by secreting toxic substances or by competing with pathogenic bacteria for nutrients or attachment to cell surfaces.