Innate Nonspecific Host Defenses Practice Flashcards

Comprehensive vocabulary flashcards covering physical, chemical, and cellular innate nonspecific host defenses, including cell junctions, antimicrobial peptides, cytokines, leukocytes, and the stages of phagocytosis.

Tight junctions

Connections that rivet two adjacent cells together, Preventing or limiting material exchange through the spaces between them.

Desmosomes

Connections with intermediate fibers that act like shoelaces, tying two cells together and allowing small materials to pass through the resulting spaces.

Gap junctions

Channels between two cells that permit their communication via signals.

Mucociliary escalator

A mechanism where ciliated epithelial cells in the trachea push mucus and trapped debris or microorganisms away from the lungs toward the esophagus for removal.

Goblet cells

Epithelial cells that produce and secrete mucus.

Bacteriocins

Antimicrobial peptides secreted by resident microbiota in the gastrointestinal tract that disrupt bacterial membranes.

Defensins

Antimicrobial peptides secreted by epithelial cells, macrophages, and neutrophils throughout the body that disrupt the membranes of fungi, bacteria, and many viruses.

Dermicidin

Antimicrobial peptide secreted by sweat glands on the skin that disrupts membrane integrity and ion channels of bacteria and fungi.

Opsonization

The process where proteins like C-reactive protein or complement proteins ($C3b$ and $C4b$) coat bacteria to prepare them for ingestion by phagocytes.

Membrane attack complex (MAC)

A ring structure formed by complement proteins $C6$ through $C9$ that punches through the cell membrane of invading pathogens, causing them to swell and burst.

Autocrine

A cytokine action where the same cell that releases the cytokine is the target.

Paracrine

A cytokine action that targets nearby cells.

Endocrine

A cytokine action where cytokine signals are delivered to distant cells via the circulatory system.

Interferons (\text{IFN-}\boldsymbol{\text{\alpha}} and \text{IFN-}\boldsymbol{\text{\beta}})$$

Cytokines released by virus-infected cells that signal uninfected neighboring cells to inhibit mRNA synthesis, destroy RNA, and reduce protein synthesis.

Neutrophils

The most common leukocyte ($1800-7300$ per $\mu L$) that is primarily phagocytic and effective against bacteria; they release cytotoxic chemicals from granules.

Eosinophils

Leukocytes ($0-700$ per $\mu L$) that are active against antigen-antibody complexes and release degradative enzymes to combat parasitic infections.

NK cells (Natural Killer cells)

Nonspecific lymphocytes that recognize and kill abnormal cells (cancer or virus-infected) that have reduced expression of MHC and increased expression of activating molecules.

Monocytes

Large, agranular white blood cells with an indented nucleus that differentiate into macrophages and dendritic cells after leaving the bloodstream.

PAMPs

Pathogen-associated molecular patterns; molecular signatures found on pathogens that are recognized by phagocytic cells.

PRRs

Pattern recognition receptors; receptors on phagocytes capable of recognizing various PAMPs to activate genes for phagocytosis and cytokine production.

Phagolysosome

The structure formed by the fusion of a phagosome with a lysosome where pathogenic particles are digested by enzymes.

Histamine

An inflammation-eliciting mediator that promotes vasodilation, bronchoconstriction, smooth muscle contraction, and increased mucus production.

Bradykinin

An inflammation-eliciting mediator that increases vasodilation and vascular permeability, leading to edema.