The Immune System

pathogen + types

a pathogen is an agent that causes disease

• bacteria, viruses, fungi, and parasites

antigen

An antigen is any molecule that elicits an adaptive immune response

• dependent molecules that protrude from pathogens or other particles.

• viruses, bacteria, and mold spores.

antibody (vs antigen)

An antibody is an immune protein found in blood plasma

• Antibodies attach to one particular kind of antigen and help to counter its effects

• made by b cells

antigen x b cell

each b cell has an antibody on its surface that matches with a specific antigen

innate vs adaptive immunity

innate: always deployed, active immediately, same regardless of if pathogen is known

• 1st & 2nd line of defense/ primary response

adaptive: deployed only when infectious agent is recognized

• 3rd line of defense

active vs passive immunity

both adaptive immunity

• Active immunity: when a person’s own immune system actively produces antibodies in response to natural or artificially antigens

• Passive immunity: when a person receives pre-made antibodies that they get from their mother or pills (her exposure, vaccination, etc)

Types of White Blood Cells

• Granulocytes: innate

  • Neutrophils, Basophils, Eosinophils

  • mast cell

• Monocytes: both

  • Macrophage, dendrite

• Lymphocytes: adaptive

  • T & B cells

Innate Response 1

1st line of defense: Skin, mucous membranes → secretions

made of phagocytic white blood cells

complement system (proteins, recruit wbcs)

Innate response 2

2nd line of defense:

• phagocytic WBCs engulf pathogens

• proteins

• inflammatory response

phagocytic

white blood cells that engulf and digest pathogens.

inflammatory response

adaptive response WBC’s go to infected area & phagocytose pathogens, then die, and produce pus

• symptoms: redness, warmth, swelling, fever

allergies

When immune system recognizes something harmless (pollen, peanuts, etc.) as a pathogen (foreign antigen) and mounts an immune response to it

2 types of adaptive immunity

Humoral Immune Response → B cells, external antigen

Cell-mediated Immune Response → Killer T cells, infected cell

Humoral Immune Response

Primary: B cells produce antibodies that flag infection→ allow T-cells to engulf

Antibodies + Macrophages kill antigens/virus inside the humors (fluids) of our body

Secondary: memory B cells & antibodies from past infections will now immediately response when pathogen reappears

• tons of plasma cells are produced from b cell

Cell-mediated Immune Response

Primary: Kills cells via apoptosis, lysis, or phagocytosis: Helper T-cells trigger responses (killer-t) are responsible

Killer T-cells kill antigens/viruses in cells that are already infected.

helper t cells

stimulate B-cells to make antibodies and help killer cells develop.

killer t cells

directly kill cells that have already been infected

plasma cells

produce tons of antibodies → attach to antigens

if body doesnt work: antibiotics

• antibiotics: target bacteria, disrupt making of bacterium cell wall = cytoplasm leaks, bacterium dies), & disrupt RNA, protein synthesis, & DNA replication

if body doesnt work: vaccines

• vaccines: stimulate immune response without causing disease. They prepare the immune system to recognize and combat pathogens more effectively (no cell wall)

vaccines vs antibiotics

vaccines:

• prevent/ taken before infection

• teach bodies to produce own antibodies to recognize and kill antigen/pathogen

• work against viral + some bacterial infections

antibiotics:

• react/ taken after infection

• target and kill bacteria

• only work against bacterial infections (not viral)