Immune System

Question 1

What is immune system

Answer 1

Body’s ability to resist or eliminate potentially harmful foreign materials (pathogens)

Question 2

Types of pathogen

Answer 2

Virus bacteria parasite fungi Protozoa

Question 3

Types of immunity

Answer 3

Acquired immunity and innate immunity

Question 4

External barriers

Answer 4

Skin and mucus
Fluids eg sweat saliva (lysozymes)
Stomach (digestive enzymes and gastric acid)

Question 5

Innate immunity

Answer 5

Always ready to attack. Many pathogenic microbes have evolved to resist innate immunity
Non specific- cannot distinguish between pathogens
Fast and immediate
No memory

Question 6

Cells of innate immunity

Answer 6

Phagocytes, dentritic cells, NK cells and complements

Question 7

Adaptive immunity

Answer 7

stimulated by exposure to microbe, more potent
Highly specific- distinguishes using shapes on surface called antigens
Slower
Immunological memory

Question 8

Cells of adaptive immunity

Answer 8

B lymphocytes and T lymphocytes

Question 9

Types of innate immunity

Answer 9

Cellular - phagocytes, eosinophils, basophils, chemical- cytokines

Question 10

Phagocytes are

Answer 10

Cells that track down, engulf and destroy bacteria, other pathogens and our own damaged and dead cells

Question 11

Types of phagocytes

Answer 11

Neutrophils (most abundant) monocytes/ macrophages

Question 12

Neutrophils work how

Answer 12

Contain destructive enzymes such as peroxidases, alkaline and acid phosphates which kill and destroy bacteria and other pathogens

Question 13

Monocytes work how

Answer 13

Larger than neutrophils so can engulf bigger pathogens. Break down pathogens and process the antigens then present these antigens to the cells of the adaptive immunity to produce specific immune response
APCs (antigen presenting cells)

Question 14

How does the process Phagocytosis go

Answer 14

Microbes attach to phagocyte surface, endocytosis of microbe and formation of phagosome, fusion of phagosome and lysosome, killing of microbe through digestion by enzyme, discharge of waste

Question 15

Lysozyme

Answer 15

Digests bacterial cell wall

Question 16

Eosinophils do what

Answer 16

Help combat parasitic infections, involved in allergy and asthma, contain enzymes

Question 17

How do u experience an allergic reaction or asthma attack

Answer 17

The body reacting to histamine which is released by mast cell which is activated by allergen. Histamine targets receptors on a specific tissue and trigger a specific reaction eg itchiness in the skin

Question 18

Basophils

Answer 18

Least common white blood cells, contain large cytoplasmic granules with inflammatory mediators, no proven function, found in parasitic infections

Question 19

Cytokines are

Answer 19

Small proteins secreted by cells in response to stimulus. Trigger biological responses when they bind to specific receptors

Question 20

Where are lymphocytes produced

Answer 20

Bone marrow

Question 21

Lymphatic system does what

Answer 21

Transport of white blood cells. Drainage of tissues, absorption and transport of fatty acids and fat, immunity

Question 22

lymphatic organs primary and secondary

Answer 22

Bone marrow and thymus

Lymph nodes and spleen and tonsils

Question 23

What happens in primary lymphoid organs

Answer 23

Where blood cells are produced (hematopoiesis in bone marrow) and B cells receive this early training- acquire ability to interact with antigens

Question 24

What happens in thymus

Answer 24

T cells are educated. In cortex they are mature, medulla they are immature

Question 25

What do lymph nodes do

Answer 25

Induce adaptive immune responses to antigens carried from the tissues by lymph

Question 26

3 phases of immune defence

Answer 26

Recognition of danger, production of specific weapons, transport of weapons to site of attack

Question 27

Spleen

Answer 27

Acts as a filter for blood by recycling old RBCs and platelets and white blood cells are stored there

Question 28

What are T lymphocytes responsible for

Answer 28

Cell mediated immunity and assisting B cells

Question 29

Types of t lymphocytes

Answer 29

Cytotoxic T cells (CD8+) and Helper T cells (CD4+)

Question 30

Cytotoxic T cells function and when does it recognise antigens

Answer 30

Kill cells When they’re bound to MHC I

Question 31

Helper T cells function and when does it recognise antigens

Answer 31

Stimulate B cells to produce antibody. Cannot kill pathogens but can activate and direct other cells. bound to MHC II

Question 32

What does perforin do

Answer 32

Creates holes in infected cell where enzymes that promote apoptosis can enter

Question 33

What is MHC I

Answer 33

Self-nonself complex that is responsible for the presentation of an antigen on the pathogen. Found on virtually all nucleated cells. Endogenous pathway. Presents antigen to CD8+ cells

Question 34

Classes of TH cell and their target cell

Answer 34

TH1 - macrophages TH2 - eosinophils TH17- neutrophils TfH- B cells

Question 35

What is MHC II

Answer 35

Found only on professional antigen presenting cells ie macrophages. Presents exogenously produced antigen to CD4+ T cells

Question 36

What do B cells do

Answer 36

Produce antibodies directed against antigens. They express B cell receptors BCRs and on activation they are differentiated into plasma cells with the help of T helper cells. Also produce memory B cells

Question 37

What are antigens

Answer 37

Small proteins on the surface of a pathogen that are recognised by antibodies

Question 38

Two regions of antibody

Answer 38

Antigen binding region- upper region and the part that recognises antigens Fc region- lower region solid and stable part that attaches to surface of B cell (has disulphides bonds)

Question 39

Types of antibody (5)

Answer 39

``` IgM- first class to be produced, less specificity IgA- protects mucosal surfaces IgE- defends against parasites and causes allergies IgD- unknown function IgG- main type ```

Question 40

Functions of antibodies

Answer 40

Neutralisation- prevention of attachment and entry of cell free viruses (mostly IgA) opsonisation- helps direct macrophages towards certain pathogens by adding lots of antibodies to the pathogens complement activation

Question 41

Complement system

Answer 41

Consists of more than 30 proteins/ factors that are found in plasma, in an inactive form. Activated in a cascade like format.

Question 42

Types of pathway of complement system

Answer 42

Alternative, classical, lectin

Question 43

What is the result of complement system and what effect does it have on microbes

Answer 43

Membrane attack complex MAC Creates a cytotoxic pore and liquid leaks out, killing the cell

Question 44

Functions of complement system

Answer 44

Direct lysis of target cells, recruit other immune cells to the site of infection to enhance the immune response, produce things that enhance phagocytosis

Question 45

Passive immunity

Answer 45

Transfer of antibodies or lymphocytes specific for the microbe B memory cells are not present and it is a short lived solution

Question 46

Active immunity

Answer 46

Protective immunity against a pathogen may be induced through the hosts own response to that pathogen B memory cells are made and this is a long term or permanent solution