IB BIO HL: Defense Against Disease

Pathogen

disease-causing organisms and viruses

Immune system

defends the body against infection by pathogens

Skin

physical and chemical barrier of immune system

• prevents pathogens from entering + secretes lactic acids and fatty acids preventing growth of pathogens

Mucous membrane

soft areas of skin that are kept soft with mucus

• produce lysozymes that trap pathogens

Lysozyme

enzyme that catalyzes the destruction of the cells walls in certain bacteria

Clotting factors

released by damaged tissues and platelets, initiating cascade of reactions

Prothrombin

activated by clotting factors

activates to thrombin

Thrombin

activated by prothrombin

activates soluble fibrinogen

Fibrinogen

activated by thrombin

activates insoluble fibrin

Fibrin

activated by fibrinogen

forms a mesh around wounds, trapping blood cells, to form a semi-solid clot

Innate immune system

a non-specific response to a broad range of pathogens

• DOES NOT change

• Phagocytes

Adaptive immune system

a specific targeted response to a specific pathogen

• Antibodies

• Memory cells

Phagocyte

white blood cells

• can leave bloodstream using ameboid motion

  • EAT pathogens via endocytosis

Antigen

a toxin or other foreign substance that causes an immune response in the body

Antibody

blood protein produced in response to a specific antigen

Lysosome

membrane-bound organelle that contains digestive enzymes

Phagosome

vesicle formed around a phagocyte

Lymphocytes

group of white blood cells which recognize and target pathogens, in BLOODSTREAM

• Helper T-lymphocytes

• B-lymphocytes

T-4 helper lymphocytes (helper T-cells)

white blood cells part of adaptive immune system

• activate other immune cells to fight infections like B-cells and killer T-cells

Glycoproteins

most antigens

MHC protein

cell surface molecules that appear on T-cells, allows binding to pathogens

Plasma cells

type of immune cell that makes large amounts of a specific antibody

Memory cells

allow quick recognition and destruction of reoccurring pathogens

• created when body encounters new pathogen (ex: vaccine)

Clonal selection

theory explaining how body produces antibodies to fight infections

Immunity

ability of the body to eliminate an infectious disease from body

HIV

• caused AIDS

• transmitted through sharing of body fluids

• infects and kills CD4 cells (Helper T-lymphocytes)

AIDS

• caused by HIV

• weakens the immune system

Antibiotics

chemicals that inhibit growth of or kill bacteria

Natural selection

process that states that randomly mutated adaptations that improve organism’s ability to live longer or reproduce will outlive those that do not have these adaptations

Zoonoses

infectious diseases that can transfer from other species to humans

Vaccines

stimulate an adaptive immune response to a particular disease-causing pathogen

• contain either antigens or nucleic acids (that codes for antigens)

Immunization

making a person or animal resistant to an infectious disease using vaccines

Herd immunity

the resistance to the spread of an infectious disease with a population

Pandemic

an epidemic that has spread over multiple countries or continents

Epidemic

when an infectious disease affects a large number of people within a community, population, or region

Percentage difference

• allows comparison of 2 values

  • (final - initial) / (average) x 100

Percentage change

(final - initial) / (initial) x 100