Innate (non-specific) physical, chemical and biological defences

Innate (Non-specific) Physical Defences

Skin: Known as the first line of defence, your skin physically blocks infection from entering the body. It is tough and impermeable to water and various pathogens.
Mucous Membranes: These line the body’s internal cavities that are exposed to the exterior (nasal passages, throat, lungs, etc.) and secrete a sticky mucus. Many harmful bacteria and viruses get trapped in this mucus.
Cilia: These are tiny hair-like structures in the airways and respiratory tract that move in coordinated waves. By doing this, they drive out mucus and pathogens, helping to prevent infection.
Coughing and Sneezing: Another part of the first line of defence, your body will sneeze or cough to physically eject pathogens from the respiratory tract.

Innate (Non-specific) Chemical Defences

Saliva and Tears: These contain the enzyme lysozyme, which can break down the cell wall of many bacteria, helping to prevent infection.
Gastric Juice: Found in the stomach, this is a mix of hydrochloric acid and enzymes. It can kill many pathogens that have been swallowed.
Sebum: This is an oil produced by the skin that contains substances harmful to many pathogens.
Perspiration: Sweat from the skin helps to maintain an environment that is not favourable for the growth of many pathogens.

Innate (Non-specific) Biological Defences

Normal Flora: They are beneficial microorganisms that live on the skin and in certain areas of the body (like the gut). They compete with pathogens for space and nutrients, effectively outcompeting many harmful microorganisms.
Phagocytosis: This is the process by which certain cells called phagocytes engulf and destroy pathogens. This is a key part of the bodys innate (non-specific) immune response.
Interferon: This is a substance released by cells that have been infected by a virus. It causes nearby cells to increase their defences against viral infection.