Introduction to Immunology

Question 1

Are viruses extracellular or intracellular pathogens?

Answer 1

intracellular pathogens

Question 2

What are the bodies defence mechanisms?

Answer 2

Innate (first line of defence)

Adaptive (second line of defence)

Question 3

What are the features of the innate immune system?

Answer 3

• activated immediately by pathogens
• non-specific
• acts fast
• physical barriers, defence mechanisms (biochemical), general immune responses (immune cells)
• first line of defence

Question 4

What do physical barriers include?

Answer 4

skin, go tract, cilia, hair …

Question 5

What do defence mechanisms include (biochemical)?

Answer 5

secretions, mucous, bile …

low pH, lysosomes (enzymes that damage cell wall of bacteria)

Question 6

What do general immune responses include?

Answer 6

• inflammation - increased blood flow so more cells to area
• complement - immune response that enhances the ability of antibodies and phagocytes to clear microbes and damaged cells, promotes inflammation and attacks pathogen membrane
• non specific cell responses

Question 7

What do the non specific cell response cells include?

Answer 7

• phagocytes
• macrophages
• mast cells
• neutrophils
• natural killer cells
• dendritic cells

Question 8

What are the features of the adaptive immune system?

Answer 8

• activated by exposure to pathogens and uses immunological memory to enhance immune response
• slower
• specific
• generates memory
• improved by further exposure

Question 9

What type of cell are used in the adaptive immune system?

Answer 9

lymphocytes
- b cells
- T cells
derived from hematopoietic stem cells in bone marrow

Question 10

Phagocytes?

Answer 10

circulate the body looking for potential threats to engulf and kill

Question 11

Macrophages?

Answer 11

can leave circulatory system across capillaries - to release cytokines to signal and recruit other cells to the area with pathogens
(in blood stream called monocytes in tissues become macrophages)

Question 12

Mast cells?

Answer 12

release cytokines and granules to create an inflammatory cascade

Question 13

Neutrophils?

Answer 13

phagocytic, granulocyte, toxic to bacteria and fungi

Question 14

Natural killer cells?

Answer 14

destroy infected host cells instead of pathogen themselves

Question 15

How does inflamation aid in immune responses?

Answer 15

increased blood flow to the area encourages more immune cells to the area

Question 16

How does phagocytosis occur?

Answer 16

phagocyte engulfs pathogen and forms a phagosome
lysosome damages and digests the pathogen
the microbial products are released

Question 17

What does lysine contain to make it toxic to bacteria?

Answer 17

• free radicals
• enzymes
• breaks down cell wall of bacteria

Question 18

What are the chemical mediators of the immune system?

Answer 18

• acute phase proteins
• complement proteins
• interferons
• cytokines

Question 19

What are cytokines?

Answer 19

a substance that is secreted by certain immune cells and have an effect on other cells

Question 20

What is CRP?

Answer 20

• blood test marker for inflammation in the body
• leves rise due to inflammation
• responds rapidly - early indicator

Question 21

What is the complement system?

Answer 21

part of the immune system that enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promotes inflammation and attacks the pathogen’s cell membrane - helps with opsonization

Question 22

What is opsonin?

Answer 22

substance that coats cell/bacteria making them more susceptible to phagocytosis

Question 23

What is opsonization?

Answer 23

process of coating cell/bacteria with an opsonin

Question 24

What are interferons?

Answer 24

a group of signalling proteins made and released by host cells in response to the presence of pathogens and tumour cells

Question 25

What are the functions of interferons?

Answer 25

- tell immune system that germs or cancer cells are in the body - trigger killer immune cells to fight invaders - interfere with viruses to stop them multiplying

Question 26

What are the types of interferon?

Answer 26

INFa INFb INFy

Question 27

What is the function of INFa and INFb?

Answer 27

induce viral resistance in cells - make neighbouring cells to infected cell a more hostile environment for the virus - can be secreted by many types of infected cells including leucocytes and fibroblasts

Question 28

What is the function of INFy?

Answer 28

signal the immune system to respond | - secreted by natural killer cells and T lymphocytes

Question 29

How do interferons work?

Answer 29

infected cells give of INFa and INFb as a warning signal to the immune system - triggering white blood cells to release INFy

Question 30

Lifecycle of a virus?

Answer 30

- virus infects cell - viral replication - produces new viral proteins and secretes them which may kill cell

Question 31

What is an antigen?

Answer 31

a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.

Question 32

What is an antibody?

Answer 32

An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein produced mainly by plasma cells that is used by the immune system to neutralize pathogens such as pathogenic bacteria and viruses.

Question 33

Describe the structure of an antibody?

Answer 33

- y-shaped | - specific binding sites

Question 34

Compliment and antibody together is very effective

Answer 34

-

Question 35

What happens the second time the immune system is exposed to a pathogen?

Answer 35

"secondary response" due to immunological memory | - similar response but stronger and faster

Question 36

How does the tetanus vaccination work?

Answer 36

"artificial active immunity" | - dead/weakened version of the disease enters the body which results in the production of antibodies

Question 37

what are plasma cells?

Answer 37

fully differentiated B-lymphocyte which produces a single type of antibody

Question 38

What causes autoimmune diseases?

Answer 38

antibodies bind to the body own cells and not pathogens - this causes the lysis of cells

Question 39

Why are babies not rejected in the womb?

Answer 39

in pregnancy oestrogen inhibits T cells which could reject the foetus

Question 40

What are IgG and IgA?

Answer 40

IgG (immunoglobulin)- main antibody found in blood and extracellular fluid IgA - role in infection control of mucous membranes

Question 41

When does the immune system fail?

Answer 41

- hypersensitivity - immunodeficiency - autoimmunity

Question 42

What is hypersensitivity?

Answer 42

allergic reaction | - histamine is activated

Question 43

What is immunodeficiency?

Answer 43

- repeated infections - lacking a specific immune response - certain drugs can induce this - strong steroids, chemotherapy

Question 44

What is autoimmunity?

Answer 44

- immune system reacting to itself - loss of tolerance - response can be antibody or cell mediated - rheumatoid arthiritus, type 1 diabetes