LESSON 1 (PART 1)

immune system

a host defense system against infectious diseases and foreign (non-self) antigens

immunology

a field that deals with the host defense reactions to falling entities known as antigens

immune response

a response generated against a potential pathogen

antibody

a protein that is produced in response to a particular pathogen

antigen

the substance that induces the production of antibodies

innate immunity

• inborn / natural defense

• antigen non-specific

• no memory, not long-lasting protection

  • skin (barrier)

  • phagocytes (engulfing bacteria)

  • inflammation

adaptive immunity

• acquired learned defense

• highly antigen specific

• has memory. responds rapidly and vigorously to second antigen exposure

  • B-cells

  • T-cells

natural adaptive immunity

came from a natural response (not from science)

active (infection)

• results when exposure to a disease organism triggers the immune system to produce antibodies to that disease.

• can be acquired through natural immunity or vaccine-induced immunity

passive (maternal)

antibodies pass from mother to fetus via placenta or to infant via the mother’s milk

artificial

• medical interventions

  • vaccine

  • injections

active (immunization)

• acquired immunity refers to any immunization with an antigen.

• by giving a safe form of the antigen artificially, the body will produce its own antibodies

passive (antibody transfer)

the short-term protection a person receives from receiving pre-formed antibodies from an external source, such as another person or animal, rather than producing them themselves.

epithelial layer

the skin airways, gastrointestinal (GI) tract and genitourinary tract have __ cell as their barrier

microbial attachment

mucosal surface and ciliated epithelial cells inhibit __ and limit exposure time

GI tract

has mechanism to inhibit bacteria

stomach acid

• has high acid level

• can kill microbes

digestive enzymes

destroys pathogens

gut microbiota

good bacteria that fights bad bacteria

acidic pH

__ in sweat and sebaceous secretions

false

(true or false) innate immunity generates an antigen specific immunity

microbial sensors

When a pathogen enters the skin, it is confronted by macrophages and other phagocytic cells possessing __

toll-like receptors (TLRs)

• best studied of the microbial sensors, transmembrane proteins that recognize pathogen-associated molecular patterns

• outside the cell

nod-like receptors (NLRs)

intracellular sensors for microbial

RIG-1-like helicase and MDA5

• viral detection

• can detect viral RNA inside an infected cell

• produces interferons to prevent the increase of virus

phagocytic cells

• eating cells

• are present in the blood, lymphoid tissue, liver, spleen, lung and other tissues and are basically in-charge in engulfing unwanted pathogens – through the process of chemotaxis, migration, ingestion and killing.

natural killer (NK) cells

• directly killing virally infected and cancerous cells.

  • kill virus-infected cells,

  • kill tumor / cancer cells

  • release toxic granules

toxic granules

release perforin (pore formation of cells) and granzymes (entering enzymes that kills specific target)

complement system

• molecular alarm systems

• attracts immune cells

• cell lysis (rupturing membranes of foreign cells)

• enhancing phagocytosis of antigens

inflammatory response

occurs when tissues are injured by bacteria, trauma, toxins, heat, or any other cause.

fever

• high body temperature

• booster of immune system

• slows down the growth of microbes

• speeds up the activity of immune system

interferons

warning signal proteins in infected cells

red blood cells
white blood cells
platelets

cellular components of blood

neutrophils

• first responders

• rapid phagocytosis bacteria of

• the most common type of white blood cell in the body, serving as the immune system's first line of defense against infection and injury.

monocyte / macrophage

eats pathogens and cell debris (garbage collector)

dendritic cell

• phagocytic cell

• initiating all antigen-specific to t-cell

• bridge to adaptive immunity

eosinophil and basophil

defense against parasites and allergy reactions

chemotaxis

chemical signals attract phagocytes to microorganisms

adherence

• attachment of phagocyte to surface of MO

• facilitated by opsonins

opsonins

antibodies / complement proteins

ingestion

• phagocyte engulfs microbes

phagosome

a membrane-bound vesicle that forms within a cell as it engulfs a microbe

digestion

• MO is digested inside the phagolysosome

• phagosome fused with lysosome forming a phagolysosome

• destroy microbes using enzymes, acids, reactive oxygen species

acute inflammation

first response of the body when it has infection or tissue injury

neutrophils

• phagocytosis

• first to engulf bacteria

• short-lived

basophils

• histamine production

• produce chemicals for inflammation (responsible for swelling and redness)

eosinophils

phagocytosis + destruction of parasites

macrophages

• phagocytosis (long-lived)

• engulf and kills pathogens, process and present antigen, and regulate immune reactivity

dendritic cell

• phagocytosis + T cell activation

• cause degradation of pathogens upon activation of the T-cells by acting as an antigen-presenting cell and by producing regulatory cytokines.

infected cells

does not present the MHC I, but does present ligands for the activating receptor

normal cell

presents the MHC I