Inflammation, Immunology & Immunological Disorders

Flashcards covering the phases of inflammation, the function of various leukocytes, cytokine signaling, and the mechanisms of innate and adaptive immunity.

Initiation of Inflammation

The process where pattern recognition receptors (e.g., toll-like receptors) on innate immune cells recognize pathogen-associated molecular patterns or damage-associated molecular patterns to trigger pro-inflammatory mediators.

Pro-inflammatory Mediators

Substances such as cytokines ($\text{TNF-}\alpha$, $IL-1$, $IL-6$), chemokines, histamine, and prostaglandins that increase blood flow and local vascular permeability.

Cardinal Signs of Inflammation

The four characteristic signs: redness (rubor), heat (calor), swelling (tumor), and pain (dolor).

Leukocytes

White blood cells responsible for protecting the body from infections; they are categorized into granular and agranular groups.

Neutrophils

The body's first line of cellular defense and the first white blood cells to arrive at a site of injury; they destroy bacteria and fungi through phagocytosis.

Diapedesis

The process by which neutrophils leave the bloodstream by squeezing through capillary walls.

Chemotaxis

The movement of immune cells toward a site of infection in response to chemical signals.

Monocytes

The largest white blood cells which circulate in the bloodstream for $1-3$ days before entering tissues and transforming into macrophages.

B Lymphocytes (B Cells)

Cells that provide adaptive immune responses by producing antibodies to mark pathogens and forming memory cells for future recognition.

T-Lymphocytes (T Cells)

Cells originating in the bone marrow and maturing in the thymus that provide cell-mediated immunity without producing antibodies.

Helper T Cells ($CD4^+$)

T cells that coordinate the immune response by activating B cells and other white blood cells through the secretion of cytokines.

Cytotoxic T Cells ($CD8^+$)

T cells that directly destroy infected or abnormal cells by releasing cytotoxic granules containing perforin and granzymes.

Acute Inflammation

A short-term, rapid response lasting minutes to days, mediated primarily by neutrophils and macrophages.

Chronic Inflammation

A prolonged response lasting weeks to years, characterized by simultaneous tissue destruction and repair, predominantly involving macrophages and lymphocytes.

Cytokines

Small signaling proteins that regulate immunity and inflammation; their signaling can be autocrine, paracrine, or endocrine.

Mast Cells

Innate immune cells found in interface tissues that release histamine and other mediators during allergic reactions and wound healing.

Complement System

A group of $>30$ proteins that enhance phagocytosis, form the membrane attack complex (MAC) to lyse pathogens, and promote inflammation.

Anaphylatoxins

Complement components such as $C3a$ and $C5a$ that increase vascular permeability and activate mast cells.

Pyrogens

Chemicals secreted by white blood cells that reset the hypothalamic thermostat to induce fever.

Lysozyme

An antimicrobial substance found in perspiration, tears, saliva, and nasal secretions that destroys bacteria.

Immunocompetence

The ability of the immune system to carry out adaptive immune responses by recognizing specific antigens.

Naturally Acquired Passive Immunity

The transfer of antibodies from mother to fetus via the placenta ($IgG$) or to an infant through breast milk ($IgA$).