Innate Immune System

Immunity

Body’s ability to protect itself by resisting or elimination potentially harmful foreign invaders or abnormal cells

Immune System Functions

Defending against invading pathogens

removing worn-out cells and damaged tissue

Immune Surveillance-identifying and destroying abnormal cancer cells that have originated in the body

Major Targets of Immune System

pathogenic bacteria and viruses

virulence: disease-producing power of a pathogen

Effector Cells of Immune System

Leukocytes

5 types: neutrophils (most prevalent), eosinophils, basophils (least prevelant), monocytes, and lymphocytes

Lymphoid Tissues

tissues that produce, store, or process lymphocytes

ex. bone marrow

Innate Responses

Nonselectively defends against foreign material

responses work immediately upon exposure

rapid by limited and nonselective response to unfriendly changes of all kinds

Adaptive Responses

Selectively targets particular invaders

customizes defenses for specific pathogens

Innate Defenses

Inflammation-nonspecific response to tissue injury (neutrophils and macrophages)

Interferon-defense against viral infection

Natural Cell Killers- destruction of virus-infected and cancer cells

Complement System- plasma proteins that destroy foreign cells

Inflammation

nonspecific response to foreign invasion or tissue damage

defense by resident tissue macrophages, localized vasodilation, localized capillary permeability, localized edema, tissue repair

chronic inflammation occurs when the triggering agent persists long term

NSAIDs and glucocorticoids suppress inflammation

Interferon

transiently inhibits multiplication of viruses in most cells

released from virus-infected cells-briefly provides nonspecific resistance to viral infections

Antiviral effect of interferon-acts as whistleblower

Anticancer effects of interferon- markedly enhances actions of cell-killing cells

Natural Killer Cells

destroy virus-infected cells and cancer cells on first exposure to them- naturally occurring, lymphocyte like cells

Complement System

punches holes in microorganisms

pathways: alternate and classic complex

Formation of the membrane attack complex: C5 through C9 assemble into a large, doughnut-shaped protein complex

Alternate Complement Pathway

binding directly to a foreign invader nonspecifically activates the complement cascade (an innate immune response)

Classical Complement Pathway

binding to antibodies produced against and attached to a particular foreign invader specifically activates the complement cascade (an adaptive immune response)

Augmenting Inflammation

activated proteins in the complement cascade act on their own to augment the inflammatory process by serving as chemotoxins, acting as opsonin, promoting vasodilation, and increasing vascular permeability

Skin

External Defense

consists of an outer protective epidermis and an inner, connective tissue dermis

Cells in the epidermis produce melanin, keratin, and vitamin D and participate in immune defense