Responding to Antigens

Question 1

Immune System

Answer 1

a group of tissues and organs that assist the body in resisting infection and disease through specialised cells

Question 2

Innate Immunity

Answer 2

Group of defences that the body has against all infections. Provides immediate protection against pathogens.
Born with it. Non-specific

Question 3

Adaptive Immunity

Answer 3

Involves specialised cells and antibodies against specific antigens. People produce their own antibodies to an antigen. Specific, acquired immunity.

Question 4

First line of defence (innate immunity)

Answer 4

consists of physical and chemical barriers to prevent pathogens from entering body.

Question 5

Lysosomes

Answer 5

organelles containing digestive enzymes and fuse with pathogen to remove from the cell

Question 6

Physical examples of first line of defence in animals and humans

Answer 6

Intact skin 
Eyelashes 
Nostril hair 
Tight Junction 
Natural Flora

Question 7

Chemical examples of first line of defence in animals and humans

Answer 7

Saliva 
Sweat 
Tears 
Ear wax
Mucous

Question 8

Flushing examples of first line of defence in animals and humans

Answer 8

cough - lungs
vomit - stomach
diarrhoea - intestine

Question 9

Chemical examples of first line of defence in plants

Answer 9

toxins in fruit,
bad-tasting chemicals in leaves,
tannins in stems,
pheromones,

Question 10

Second line of defence (innate immunity)

Answer 10

nonspecific resistance that destroys invaders in a generalised way without targeting specific individuals

Question 11

Second line of defence examples

Answer 11

Fever - the body sets temp higher, aiming to kill foreign material. Higher temp excelerates, repairs and slows virus.

Cytokines - signalling molecules in the immune response. i.e starts inflammation, fever.

Complement proteins - proteins that contribute to secondary defense. Kills bacteria directly, signals to the rest of the immune system, coats pathogens and makes it easier to identify

Phagocytes - white blood cells that engulf and destroy foreign material. Neutrophil = short lived
Macrophage = long lived

Natural killer cells - type of white blood cells that kills virus infected and tumour cells

Question 12

Inflammatory Response

Answer 12

1. bacteria and other pathogens enter wound
2. platelets help clot at wound site
3. mast cells secrete histamine which causes vinsolidation (delivery of blood & immune cells to areas in need
4. neutrophils engulf and kill pathogens
5. macrophages secrete cytokines to attract immune system cells and activate tissue repair
6. inflammatory response continues until foreign objects are eliminated and wounds is repaired

Question 13

Complement proteins

Answer 13

inactive proteins found in the bloodstream. Activated in the innate immune system by non-self antigens. Activated in humoral immune system by antibodies.

Question 14

Oponisation

Answer 14

complement proteins bind to antigens on the pathogen. Prevents the pathogen from binding to non-infected cells

Question 15

Lysis of pathogens

Answer 15

occurs when a membrane-attack complex (MAC) forms on the plasma membrane of the pathogen. MAC inserts into plasma membrane of pathogen and produces a pore that allows fluid to enter, causing pathogen cell to swell

Question 16

Interferons

Answer 16

Interferes with viral replication. Signalling molecules. Once cell is infected with a virus, the cell secretes interferons. Causes surrounding cells to become more resistant to viral entry.

Question 17

Natural Killer Cells/NK Cells

Answer 17

Type of lymphocyte. Binds to MHC 1 marker of infected cell and causes infected cell to undergo apoptosis. Protects from viral, bacterial, parasitic infections.

Question 18

Lymphocytes

Answer 18

white blood cells that are also one of the body’s main types of immune cells.

Question 19

Third line of defence (adaptive immunity)

Answer 19

Only comes into operation if the first two lines of defences fail. It’s a specific immune response consisting of actions of immune cells and antibodies specifically attacking each invading pathogen

Question 20

Humoral immunity (Adaptive immunity)

Answer 20

Involves B cells that recognise antigens or pathogens that are circulating in the lymph or blood. Favoured for extracellular pathogens (presented outside host cells)

Question 21

Cell-mediated immunity (adaptive immunity)

Answer 21

Involves T cells that bind to antigens, or activates cytotoxic T cells (cells that recognise antigens presented on MHC I marker. Favoured for intracellular pathogens (found inside host cells, often viruses)

Question 22

B cells

Answer 22

type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system by secreting antibodies.

Question 23

T cells

Answer 23

A type of white blood cell. the system that tailors the body’s immune response to specific pathogens.
T cells are like soldiers who search out and destroy the targeted invaders.

Question 24

Agglutination

Answer 24

antibodies clump the antigens together which are later destroyed by phagocytes (clumping together = more easily identified, thus more quickly phagocytes)

Question 25

Neutralisation

Answer 25

antibody blocks the binding site in which antigens are presented, thereby preventing the toxin from functioning

Question 26

Complement activation

Answer 26

complement proteins are activated

Question 27

Antibody types

Answer 27

IgM, IgG, IgD, IgA, IgE

Question 28

IgM

Answer 28

antibody secreted by plasma cells in immune response (made up of 5 antibody molecules joined together)

Question 29

IgG

Answer 29

secreted after IgM in initial immune response > only antibody secreted during 2nd line of defence (is a single antibody)

Question 30

IgD

Answer 30

antibody receptor found on B cells

Question 31

IgA

Answer 31

found in respiratory and gastrointestinal tract. Neutralise infectious agents that attempt to invade through these mechanisms (made up of 2 antibody molecules joined together, end on end)

Question 32

IgE

Answer 32

involved in allergic responses