Nonspecific Defenses

Adriana Perta

Marisa Pawlowski

Paige Simko

Rachel Ragone

Jill Ross

Nonspecific Defenses

• Occur automatically because they are innate• No memory is involved- no recognition that

this same intruder has been attacked before• Barriers to entry, the inflammatory response,

phagocytes and natural killer cells, and protective proteins are types of nonspecific defenses

Immunity

• The body’s capability to remove foreign substances and to kill pathogens and cancer cells• Involves both nonspecific defenses

and specific defenses

Barriers to Entry• Include nonchemical barriers such as

the skin and the mucous membranes lining the respiratory, digestive, and urinary tracts; serve as mechanical barriers to entry by pathogens

• Also include antimicrobial molecules (ex: oil gland secretions contain chemicals that weaken or kill certain bacteria on the skin)

• The stomach has an acidic pH, which inhibits the growth of or kills many types of bacteria

Inflammatory Response(refer to page 637 figure 35.3)

• When tissue is damaged by physical or chemical agents or by pathogens, a series of events occur

• An inflamed area has four outward signs: redness, heat, swelling, and pain

• These signs are due to capillary changes in the damaged area• Histamine: a chemical signal, released by damaged tissue cells

and mast cells• Mast cells: a type of white blood cell in tissues, cause capillaries

to dilate and become more permeable • Some inflammatory responses trigger fever, the onset being

controlled by the brain• The fever serves to inhibit the growth of some microorganisms,

promotes accelerated tissue repair, stimulates immune cells to divide and increases the production of viral-fighting interferon

Chronic Inflammation• One that persists for weeks or longer• Often treated by administering anti-inflammatory

agents, such as aspirin, ibuprofen, or cortisone• These medications act against the chemical signals,

such as histamines, that bring about an inflammation• Chronic inflammation is thought to play a role in many

human illnesses • May lead to heart attacks, may destroy nerve cells in the

brains of Alzheimer patients, can also be involved in the development of diabetes in obese individuals

• Autoimmune diseases involve inflammation, but in these cases specific immunity seems to be the leading cause

• A healthy diet, exercise, and good dental hygiene can reduce the occurrence of inflammation and help keep us well by reducing the occurrence of chronic inflammation

Macrophages and Cytokines

• Macrophages: in tissues, that devour many pathogens and survive• Have receptors that allow them to

recognize the presence of pathogens• Release cytokines

• Cytokines: chemical signals that stimulate other white cells such as neutrophils and monocytes, that then mature into macrophages

Natural Killer Cells• Large, granular lymphocytes that kill

virus-infected cells and cancer cells by cell-to-cell contact

• Produce cytokines that stimulate these cells

• Congregate in the tonsils, lymph nodes, and spleen

• Look for a self protein on the body’s cell• Not specific; have no memory; and their

numbers do not increase after stimulation occurs

Protective Proteins(refer to page 638 figure 35.4)

• Complement: composed of a number of blood plasma proteins• “complement” certain immune responses• Involved in the inflammatory response because certain

complement proteins can bind to mast cells and trigger histamine release

• Some combine to form a membrane attack complex that produces holes in the surface of bacteria and viruses

• Interferons: proteins produced by virus-infected cells as a warning to noninfected cells in the area• Binds to receptors of noninfected cells, causing them to

prepare for a possible attack• Used as treatment in certain viral infections like

hepatitis C