Question

Define the innate nonspecific immunity.

Give some examples of physical defenses.

Identify at least 1 chemical defense, and what are the main functions of chemical defenses?

Answer 1

Innate nonspecific defense mechanisms occurs immediately or within hours of an antigen's appearance in the body. Body that responds to many antigens, not to specific antigen and generalized response to pathogen infections by the use of several non-specific immune cell such as a macrophage, neutrophil, or dendritic cell, white blood cells and plasma proteins.

Physical barriers of immune system are skin, mucous membrane, endothelia. Immune system cells attack foreign cells in the body. Physical barriers consist of cells that are tightly joined to prevent invaders from crossing through the deeper tissue. Endothelial cells that line blood vessels have very tight cell-to-cell junctions, blocking microbes from gaining access to the bloodstream.

Sebum

Fluids produced by the skin include both endogenous and exogenous mediators. Sebaceous glands in the dermis secrete an oil called sebum that is released onto the skin surface through hair follicles. This sebum is an endogenous mediator, providing an additional layer of defense by helping seal off the pore of the hair follicle, preventing bacteria on the skin’s surface from invading sweat glands and surrounding tissue.

Main functions of chemical defense:

The skin and respiratory tract secrete antimicrobial peptides such as the β-defensins. Lysozyme and phospholipase A2 in saliva, tears, and breast milk are antibacterials which are enzymes to prevent the invasion of microbes. In the stomach, gastric acid serves as a powerful chemical defense against ingested pathogens Vaginal secretions serve as a chemical barrier following menarche, when they become slightly acidic, while semen contains defensins and zinc to kill pathogen and prevent infection.