43: The Immune SystemTom Whitelaw

Max McGill

43.1 Innate ImmunityInvertebrates- They have physical and chemical

barriers to guard against microbes, as well as cell based defenses. Including, in Insects, the ability to ingest microbes in the

Hemolymph and cells can release antimicrobial peptides. Recognition Proteins

Vertebrates- Skin and Mucous Barriers, phagocytes, low ph, lysomes, inflammation, antimicrobial proteins, compliment proteins, interferons and natural killer cells

Some bacteria have an outer capsule that prevents recognition by killer cells and some can resist against degradation by lysozomes.

43.2 Acquired Immunity When pathogens are recognized, the body

releases specific T and B cells to combat the threat.

B cells recognize invaders by epitodesT cells recognize invaders by peptides

43.3 CellsB Cells produce antibodies that bind to

antigensT Cells produce antigens which antibodies

bind

43.3 Cell typesInfection of body fluids are subjected to humoral

responses and infection of body cells to cell-mediated responses

Helper T Cells- makes CD4 which enhances binding to class II MHC molecule- antigen fragment complexes

Activated Versions secrete proteins to destroy target cells by other lymphocytes

Cytotoxic T Cells- Make CD8 enhances binding to class I MHC complexes

Active versions secrete proteins that causedestruction of target cells

43.3 Cell TypesB Cells- Generates plasma cells that secrete

antibodiesInfected once to gain acquired immunityVacationsAntigens on blood cells determine blood type.

If different from the antigens that the body has they will be destroyed

Organs have antigens too

43.4Allergies are caused by the body attacking

innate particles Some pathogens use antigenetic variation,

latency and direct assault on immune system to weaken it

HIV destroys helper T cells Cancers are more common with

immunedeficencies and that is unclear whether it reflects reduced immune responses or increasing infections