Defense and Immunity Lecture Notes

Comprehensive vocabulary flashcards covering non-specific defense mechanisms, adaptive immunity, various cell types, immunoglobulins, and types of hypersensitivity reactions.

Non-specific Defense mechanisms

Includes epithelial barriers, phagocytes, antimicrobial chemicals, inflammatory response, and immunological surveillance.

Immunity (Adaptive or Targeted)

Includes lymphocytes, cell mediated immunity, humoral immunity (antibody mediated immunity), and acquired immunity.

Epithelial Barriers

Physical barriers like healthy intact skin and mucous membranes that protect organs and body systems using acidic or sticky secretions, antibodies, and enzymes.

Phagocytes

Cells such as Neutrophils and Macrophages that engulf and break down threats like microorganisms, antigens, debris, and dead cells using enzymes.

Hydrochloric acid

A chemical found in gastric juice where high acidity kills microorganisms.

Lysozymes

Antibacterial enzymes present in granulocytes, tears, and other body fluids that attack bacterial cell walls.

Interferons

Released by T-cells and macrophages in response to viral infection to reduce replication and spread.

Complement

A group of approximately $20$ proteins in blood and tissues activated by immune complexes or sugars on bacterial cell walls.

Inflammatory Response Signs

Redness, Pain, Heat, and Swelling.

Acute Inflammation

A response that persists for days to weeks and is generally beneficial to fight infection and promote healing.

Chronic Inflammation

A response that lasts months to years, is no longer beneficial, and can lead to lasting tissue damage.

Increased Blood Flow (Inflammation)

Arterioles dilate due to the release of histamine and serotonin, contributing to heat, redness, and swelling.

Increased Tissue Fluid Formation

Edema or swelling caused by histamine, serotonin, and prostaglandin increasing capillary permeability, allowing plasma proteins to exit and pull water via osmotic pressure.

Neutrophils

The most important WBCs in the initial phase of inflammation that migrate into surrounding tissue; they are attracted by complement, prostaglandins, and toxins.

Increased Temperature (Fever)

Triggered by the hypothalamus to inhibit pathogen growth and stimulate phagocyte activity.

Suppuration

Pus formation consisting of dead cells, fibrin, tissue exudate, and living and dead bacteria; commonly seen in Staph and Strep infections.

Abscess

A contained pus formation.

Natural Killer Cells

Specialized lymphocytes that circulate to find and destroy abnormal host cells, such as those infected by a virus or risk becoming malignant.

Specificity

The characteristic of T-cells and B-cells being programmed to respond to only one individual antigen.

Memory (Adaptive Immunity)

The ability of the immune system to respond more strongly and swiftly to future encounters with a previously exposed antigen.

Adaptation (Tolerance)

The process where immune cells recognize marker proteins on healthy body cells and only attack cells not recognized as self.

Antigen Presenting Cells (APCs)

Cells like Macrophages and Dendritic cells that display antigens on their surface to be presented to T-cells.

Cytotoxic T-cells

T-cells that directly inactivate cells carrying antigens by attaching to them and releasing toxins; they play a major role in cancer prevention.

Helper T-cells

The most common type of T-cell; they attract cytotoxic cells and macrophages via cytokines and stimulate B-cells to produce antibodies.

Regulatory T-cells

T-cells that turn off T and B cells to prevent autoimmunity and other damage by the immune response.

Memory T-cells

Cells that survive after a threat is overcome to remember an antigen and respond if it is presented again in the future.

Plasma cells

B-cells in plasma that secrete large amounts of a specific type of antibody.

Immunoglobulin A (IgA)

Found in secretions like breast milk and saliva; coats epithelial membranes to prevent antigens from invading deeper tissues.

Immunoglobulin D (IgD)

Displayed on B-cell surfaces where antigens bind to activate the B-cells.

Immunoglobulin E (IgE)

Found on cell membranes of basophils and mast cells; binds antigens to activate the inflammatory response and is often excess in allergies.

Immunoglobulin G (IgG)

The largest, longest-lived, and most common antibody; it attacks many pathogens and crosses the placenta to protect the fetus.

Immunoglobulin M (IgM)

Produced in large quantities during the primary immune response and acts as a potent activator of complement.

Primary Immune Response

The slower, less powerful response to initial exposure where IgM is the main antibody.

Secondary Immune Response

An almost immediate response due to memory cells that is $10-15 \times$ stronger than the primary response, with IgG as the main antibody.

Type 1 Hypersensitivity (Anaphylaxis)

An IgE mediated severe reaction in genetically predisposed people (Atopy) leading to edema, hives, airway narrowing, and hypotension.

Type 2 Hypersensitivity (Antibody Mediated)

Occurs when antibodies respond to self-antigens, resulting in autoimmune diseases like Rheumatoid arthritis or type 1 diabetes.

Type 3 Hypersensitivity (Immune Complex Mediated)

Condition where antibody-antigen complexes are present in excess and deposited in organs, potentially causing glomerulonephritis or chronic inflammation.

Type 4 Hypersensitivity (Cell Mediated)

A delayed over-reaction of T-cells causing chronic inflammation, such as dermatitis or graft-vs-host disease.

AIDS (Acquired Immunodeficiency Syndrome)

A condition associated with HIV that affects cells with a CD4 receptor, diagnosed when an HIV positive person presents with an AIDS defining illness.