Which are examples of nonspecific defenses

Cilia on the cells sweep and trap particles in the respiratory tract, and coughing ejects irritants. Chemical defenses. Among the nonspecific chemical defenses of the body are the secretions of lubricating glands. The tears and saliva contain the enzyme lysozyme , which breaks down the peptidoglycan of the cell wall of Gram-positive bacteria.

The lactic acid of the vagina imparts defense, and the extremely caustic hydrochloric acid of the stomach is a barrier to the intestine. Semen contains the antimicrobial substance spermine that inhibits bacteria in the male urogenital tract. Genetic barriers. The hereditary characteristics of an individual are a deterrent to disease as well. For example, humans suffer HIV infection because their T-lymphocytes have the receptor sites for the human immunodeficiency virus.

Dogs, cats, and other animals are immune to this disease because they do not possess the genes for producing the receptor sites. Conversely, humans do not suffer canine distemper because humans lack the appropriate receptor sites for the virus that causes the disease.

Macrophages, neutrophils, and eosinophils are examples of phagocytes. In their attempt to defend the body, some phagocytes stay within a tissue and others travel freely throughout the body. However, all phagocytes are attracted to sites of tissue damage. In a process called phagocytosis, these cells surround debris or a foreign invader, bringing it inside the cell. The phagocyte then uses special enzymes to digest the material.

All animals have phagocytes that recognize and eliminate foreign invaders. For example, if a piece of one sponge is transplanted to a sponge from another colony, phagocytes in the sponges will attack and destroy each other. The same response can be observed in earthworms, arthropods , starfish, and all vertebrates. Scientist Elie Metchnikoff observed this process in starfish. A colored scanning electron micrograph of a macrophage engulfing a parasite of the Leishmania genus.

To defend the body, macrophages will surround a foreign invader, bring it inside the cell, then use enzymes to digest the material. In vertebrates, some phagocytes are also important in stimulating specific immune responses. Additionally, phagocytosis is stimulated when the invaders are coated with antibodies.

Consequently, phagocytes like complement proteins represent an important link between nonspecific and specific immunity. Infection, mechanical force, chemicals, and extreme heat or cold can damage tissues, causing the nonspecific process of inflammation. The goal of inflammation is to clean up the damage and start the repair process.

Inflammation begins when damaged tissues release chemical messengers such as histamine, prostaglandins , and leukotrienes. These chemicals cause nearby blood vessels to expand and become more leaky, allowing more blood flow to the damaged area. Nonsusceptibility is the inability of certain disease-carrying organisms to grow in a particular host species. Nonsusceptibility may be caused by such conditions as lack of availability of particular growth substances needed by the infecting microorganism or body temperature unsuitable for the invading microorganism.

For example, chickens are nonsusceptible to anthrax because the bacteria cannot grow at the body temperature normal for that animal. The Columbia Electronic Encyclopedia, 6th ed. The immune system protects the body from possibly harmful substances by recognizing and responding to antigens. Antigens are substances usually proteins on the surface of cells, viruses, fungi, or bacteria. Nonliving substances such as toxins , chemicals, drugs, and foreign particles such as a splinter can also be antigens.

The immune system recognizes and destroys, or tries to destroy, substances that contain antigens. Your body's cells have proteins that are antigens. These include a group of antigens called HLA antigens. Your immune system learns to see these antigens as normal and usually does not react against them. Innate, or nonspecific, immunity is the defense system with which you were born. It protects you against all antigens. Innate immunity involves barriers that keep harmful materials from entering your body.

These barriers form the first line of defense in the immune response. Examples of innate immunity include:. Innate immunity also comes in a protein chemical form, called innate humoral immunity. Examples include the body's complement system and substances called interferon and interleukin-1 which causes fever.

If an antigen gets past these barriers, it is attacked and destroyed by other parts of the immune system. Acquired immunity is immunity that develops with exposure to various antigens.

Your immune system builds a defense against that specific antigen. Passive immunity is due to antibodies that are produced in a body other than your own. Infants have passive immunity because they are born with antibodies that are transferred through the placenta from their mother. These antibodies disappear between ages 6 and 12 months.