immunity

Question 1

what is the function of the immune system

Answer 1

Defends the body against invading pathogens
Destroys abnormal/mutant cells within the body (e.g. control of cancer)
Removes ‘worn-out’ cells

Question 2

what are harmful effects of the immune system

Answer 2

Allergies / autoimmune diseases
Tissue rejection.

Question 3

give examples of Infection-causing organisms (Pathogens)

Answer 3

BACTERIA- Staphylococcus aureus (causes sepsis)
PARASITE - Tapeworm
FUNGUS Epidermophyton floccosum (Athlete’s foot)

Question 4

name soluble mediators

Answer 4

Cytokines & chemokines
Complement proteins

Question 5

what are the central lymphoid tissues

Answer 5

bone marrow (B cell development) and thymus (T cell development)

Question 6

name peripheral lymphoid tissues

Answer 6

Spleen
Lymph nodes
Gut-associated lymphoid tissue (GALT)
[Peyer’s Patches]
Adenoids
Appendix
Tonsils

Question 7

what is a neutrophil

Answer 7

white blood cell
Destroy bacteria by phagocytosis
first defender on scene
Scavenge to clean up debris
Most abundant leukocyte (60-70%)

Question 8

what is a Eosinophil

Answer 8

white blood cell
Internal parasite infestations, such as worms: attach to worm
and secrete substances to kill it

Question 9

what is a monocyte

Answer 9

white blood cell
Mature and enlarge in resident tissue and become known as
macrophages (“large eaters”)
Emerge from bone marrow while still immature

Question 10

what is phagocytosis

Answer 10

a cell engulfs large particles, such as bacteria, dead cells, or debris, by wrapping its membrane around them to form a phagosome (vesicle). This vesicle then fuses with a lysosome, where enzymes break down the engulfed material.

Question 11

what is an example of nonspecifoc immunity

Answer 11

Phagocytosis, Inflammation

Question 12

what is nonspecific immunity

Answer 12

Initial & immediate response against invasion by any pathogens

Question 13

what are the main mechanisms in nonspecific immunity

Answer 13

1. Physical barriers (skin,
   mucous membranes)
2. Inflammation & Phagocytosis
   (by neutrophils &
   macrophages)
3. Interferon, NK cells
4. Complement

Question 14

what is an example of specific immunity

Answer 14

lymphocytes

Question 15

what is specific immunity

Answer 15

Comes into play after nonspecific responses have begun.

Responds to specific pathogens on 2nd or later exposure

Question 16

what are signs of inflammatory response

Answer 16

redness
heat
swelling
pain

Question 17

what are the stages of inflammatory repsonse

Answer 17

a) phagocytosis by nearby macrophages
b) dilation and increased permeability of capillary
c) containment of bacteria and foreign matter
d) leukocyte proliferation and migration
e) continued activity of recruited leukocytes

Question 18

what is the result of inflammatory response

Answer 18

detroys invaders
remove debris
prepares for healing and repair

Question 19

what are the stages of phagocytosis

Answer 19

1. Attachment
2. Internalisation (0.1 s)
3. Degradation (fuses with lysosomes and enzymes (break down bacteria)
4. Exocytosis

Question 20

what is interferon

Answer 20

a group of signaling proteins made and released by host cells in response to the presence of several viruses. a virus-infected cell will release interferons

• Protects other cells from any viruse
• Induces expression of enzymes that prevent viral replication
• Enhances action of NK cells and cytotoxic T cells

Question 21

what are natural killer cells

Answer 21

Attack virus-infected cells
Cause lysis via release of perforins
source for interferon Y

Question 22

what is the complement system

Answer 22

made up of a large number of plasma proteins that react with one another to opsonize pathogens and induce a series of inflammatory responses that help to fight infection

Induces lysis of invading microorganisms
Also complements the ability of other immune mechanisms to clear pathogens

Question 23

what is lysis

Answer 23

the disintegration of a cell by rupture of the cell wall or membrane.

Question 24

what are the characteristics of specific immunity

Answer 24

1. specificity
2. diversity
3. memory
4. self-tolerance

Question 25

what is specificity in specific immunity

Answer 25

Lymphocytes (B and T cells) bind and respond to foreign molecules known as antigens via antigen receptors

Question 26

what is diversity in specific immunity

Answer 26

The body possesses millions of lymphocytes that can recognise and respond to millions of antigens

Question 27

what is memory in specific immunity

Answer 27

1st exposure to an antigen generates lymphocytes & long-lived memory cells – next exposure to the same antigen, memory cells react faster & with stronger response

Question 28

what is self-tolerance in specific immunity

Answer 28

- Lymphocytes can distinguish ‘self’ (our normal antigens) from ‘non-self’ (antigens from foreign material). -B or T cells that may detect and attack ‘self’ are usually destroyed in the bone marrow. - This process of self-tolerance fails in autoimmune diseases.

Question 29

what are B lymphocytes

Answer 29

- Produce antibodies which circulate in blood - Defend mainly against bacteria toxins and viruses present in body fluids Responsible for antibody-mediated or humoral immunity

Question 30

what are T lymphocytes

Answer 30

- Do not produce antibodies - Directly destroy specific target cells by releasing chemicals that punch holes in the victim cell (cell-mediated immunity) - Target cells include body cells invaded by viruses and cancer cells

Question 31

what are the 5 classes of antibodies

Answer 31

IgM IgD IgG IgE IgA

Question 32

what are the stages of humoral immunity

Answer 32

a) neutralization b) agglutination c) opsonization d) complement activation e) enhanced NK cell activity

Question 33

what is Humoral immunity

Answer 33

an aspect of specific immune responses directed at particular antigens.

Question 34

what is opsonization

Answer 34

a process by which a pathogen is marked for phagocytosis through coating of a target cell with antibodies.

Question 35

what is agglutination in humoral immunity

Answer 35

when multiple pathogens aggregated (grouped) by antibody molecules

Question 36

what is neutralization in humoral immunity

Answer 36

when antibodies block the activity of a pathogen

Question 37

what is complement activation in humoral immunity

Answer 37

when antibodies bound to pathogens activate the complemnt cascade, resulting in lysis of the cell

Question 38

where and what are helper T cells

Answer 38

Secrete cytokines that enhance the activity of cytotoxic T cells (enhance phagocytosis) Stimulate development of B cells into plasma cells Activated by MHC (Class II) on antigen-presenting cell (e.g. macrophage)

Question 39

what are cytotoxic T cells

Answer 39

Activated by MHC (Class I) on virus-infected cell Kill infected cells by lysis (direct action)

Question 40

describe Antigen presentation and Helper T-cell activation in infected cells

Answer 40

In an infected cell, Class I MHC molecules present antigen at cell surface so cytotoxic T cells can kill the infected cell

Question 41

describe Antigen presentation and Helper T-cell activation in phagocytic immune cells

Answer 41

Class II MHC molecules present antigen at cell surface so Helper T cells can bind it and secrete cytokines that will amplify the immune response

Question 42

give an example of an autoimmune disease

Answer 42

Rheumatoid arthritis (RA) - inflammation and damage to the cartilage and bone of joints Multiple sclerosis (MS) - T cells attack myelin: - Blurred vision, - Muscle weakness, - Ataxia.