Innate Immunity: Physical and Mechanical Factors

Introduction

• The defense or resistance obtained through birth is called innate immunity. The natural defense mechanism is known as innate immunity or native immunity or natural immunity. It is inherited from parents to young ones. It is non-specific. All living organisms are naturally gifted with resistance to certain Infections from birth. It is a general protective reaction of organisms against any invasion.
• The mechanism is effective against a wide range of infectious agents. It operates through many factors such as,

1. Physical and mechanical factors
2. Biochemical factors
3. Cellular factors
4. Genetic factors
5. Body temperature
6. Inflammation
7. Fever.

Physical and mechanical factors

Skin:

• The skin is our largest organ, acts as a very good mechanical barrier to infection as it has a horny outer layer, namely stratum corneum.
• Its outermost layer, the epidermis, is composed of tightly packed cells that prevent microorganisms from entering the body.
• the skin produces sebum, which maintains an acidic pH that inhibits the growth of certain bacteria.
• Sweat glands also contribute by producing sweat, which contains lysozymes that possess antimicrobial properties.
• In the case of loss of skin due to burns, infection occurs quickly, as the microbial organisms, get an easy entry through this region.

Mucous Membranes:

• Mucous membranes line various parts of our body, including the respiratory tract, gastrointestinal tract, and reproductive organs.
• They secrete mucus, a sticky fluid that serves as a trap for pathogens.
• The mucus contains antibodies, enzymes, and antimicrobial peptides that neutralize or eliminate the trapped microorganisms.
• Coughing, sneezing, and peristalsis aid in the expulsion of the mucus and its unwanted inhabitants.

Cilia:

• Within our respiratory system, specialized cells called cilia act as microscopic brushes.
• These hair-like structures continuously beat in coordinated waves, propelling mucus and trapped pathogens out of the lungs.
• This mechanism, known as mucociliary clearance, is a vital defense mechanism against respiratory infections.
• Smoking and certain diseases can impair ciliary function, compromising the body’s ability to remove harmful particles and microorganisms.

Mechanical Forces in the Respiratory System

• When we inhale, turbulent airflow in the upper respiratory tract causes particles and microorganisms to impact the mucous membranes, reducing their chance of reaching the lower respiratory tract.
• Sneezing and coughing generate forceful expulsions, effectively clearing the airways of potential threats.
• The mechanical actions such as coughing and sneezing help in driving out the foreign particles that enter the digestive and respiratory tracts.

Gut Microbiota:

• This diverse ecosystem plays a crucial role in innate immunity.
• The gut microbiota competes with harmful pathogens for resources and produces antimicrobial substances.
• It also helps regulate the development and function of immune cells, shaping the overall immune response.

Tears and Saliva:

• Tears and saliva, often overlooked, possess antimicrobial properties that protect our eyes, mouth, and throat.
• The mouth is constantly bathed in saliva and the pathogens that enter the mouth are swallowed by the salivary secretion and are digested in the gut.
• The washing action of urine eliminates microbial organisms from urethra.

Conclusion

• Innate immunity relies on a combination of physical and mechanical factors to defend our bodies against pathogens. From the protective barrier of the skin to the sweeping action of cilia, each mechanism contributes to our overall well-being. By appreciating the intricate workings of innate immunity, we gain a deeper understanding of the remarkable defenses that keep us safe and healthy.

FAQs

Q. What is innate immunity?

A. Innate immunity refers to the body’s immediate defense mechanisms that provide the first line of protection against pathogens.

Q. How does the skin contribute to innate immunity?

A. The skin acts as a physical barrier and produces substances that inhibit the growth of microorganisms.

Q. What are mucous membranes?

A. Mucous membranes are thin linings that cover various parts of the body and secrete mucus to trap and eliminate pathogens.

Q. What is the role of cilia in innate immunity?

A. Cilia are hair-like structures that sweep mucus and trapped pathogens out of the respiratory system, aiding in their expulsion.

Q. How does the gut microbiota contribute to innate immunity?

A. The gut microbiota produces antimicrobial substances, competes with pathogens, and influences immune cell development and function.