Immune System

What is immunity?

Resistance to disease causing pathogens

What is the innate immune system composed of?

• Surface barriers - First line of defense

• Internal barriers - Second line of defense

What is the adaptive immune system (third line of defense) composed of?

• Humoral cells

• Cellular cells

What are Antigen Presenting Cells (APC)?

Cells that remember previous dangers

In terms of surface barriers, what are physical barriers and what are their function?

Physical barriers prevent entry into the body. Examples of physical barriers include skin, keratin (resistant to weak acids & bases as well as bacterial enzymes & toxins), & mucus membranes (mechanical barriers - found in various systems)

In terms of surface barriers, what are protective chemicals and what are their function?

Protective chemicals inhibit or destroy microorganisms. Examples of protective chemicals include acidity (creates an environment which bacteria dies in), lysosomes (bacteriostatic properties - inhibit growth of bacteria), mucin (add water = mucus - traps bacteria), defenses, lipids & dermicidin in tears & sweat (toxic)

What are internal defenses?

Inflammation is triggered whenever tissues are injured or infected

What does inflammation do?

• Prevents the spread of damaging agents

• Disposes of cellular debris & pathogens

• Sets the stage for repair, BUT DOES NOT REPAIR

What are signs of acute inflammation?

• Pain

• Redness

• Impairment (sometimes)

• Swelling

• Heat (within area of injury)

PRISH

What is the first step of the sequential immune response?

Leukocytosis: The process of bringing cells to the site of injury

What is the second step of the sequential immune response?

Margination: Flattening of phagocytic cells so that they can fit through continuous capillaries

What is the third step of the sequential immune response?

Transmigration: The movement of phagocytic cells from the blood vessel into the tissue

What is the fourth step of the sequential immune response?

Chemotaxis: Uses a different set of signals that bring the phagocytic cells close to the site of the injury within the tissue

What is the fifth step of the sequential immune response?

Phagocytosis: The phagocytic cell reaches out, grabs the foreign cell (psuedo pod formation), encapsulates it (phagosome forms), merges with lysosomes which breaks down phagosome (phagolysosome forms), digests and then disposes of the foreign cell (digestion & exocytosis.

What is the sixth step of the sequential immune response?

Apoptosis: Packages up all contents before it dies and disposes of it.

What are natural killer/monocytes?

Police cells: target cells that lack “self” receptors - they are good at catching cancer cells & virus infected cells

What is a cell-mediated immune response?

Provides defense against INTRAcellular antigens

What are the 4 major types of T-lymphocytes?

• Helper T-cells

• Cytotoxic T-cells

• Regulator T-cells

• Memory T-cells

What do Cytotoxic T-cells target?

• Virus-infected cells

• Cells w/ INTRAcellular bacteria or parasites

• Cancer cells

• Foreign cells

What are the functions of helper T-cells?

• Help activate B-cells & T-cells

• Induce proliferation of B-cells & T-cells

• Activate macrophage

• Secrete interleukins

• Stimulate phagocytosis

WITHOUT HELPER T-CELLS THERE IS NO IMMUNE RESPONSE

What are the two types of humoral immunity?

Active - Body makes antibodies

Passive - Antibodies are provided

What are the two types of active humoral immunity?

Naturally acquired - Infection, contact w/ pathogen

Artificially acquired - Vaccine, dead pathogen (think of it as a warning)

What are the two types of passive humoral immunity?

Naturally acquired - Antibodies passed from mother

Artificially acquired - Injection of immune serum

Which type of humoral immunity is more efficient - active or passive?

Active