basic immunology

Question 1

what is the immune system?

Answer 1

-the bodys natural defence against disease causing agents such as bacteria, viruses and parasites
-it plays an important role in identifying and eliminating abnormal cells

Question 2

what is the immune system made up of?

Answer 2

a complex and vital network of cells and organs that protect the body from infection

Question 3

what can diseases be caused by?

Answer 3

-bacteria (e.coli)
-virus (20-300nm)
-parasites (ascaris and tapeworms)

Question 4

why do pathogens invade organisms?

Answer 4

they are seeking
-source of food or water
-protection
-site for reproduction

Question 5

what are defence systems evolved to do?

Answer 5

get rid of invading organisms

Question 6

compare innate immunity to adaptive immunity

Answer 6

-natural immune system vs acquired response
-prevents or limits infection vs eradicates infection
-non specific vs highly specific

Question 7

how does the innate immune system provide broad defences against infection?

Answer 7

by the pathogen breaking through the external defences encountering, innate cellular and chemical mechanisms that impede its attack

Question 8

why is the skin and external defence?

Answer 8

-it is a physical barrier to the entry of microorganisms and viruses

Question 9

what is the structure of the skin?

Answer 9

it is layers of closely packed keratinocytes and has
➢ Antimicrobial fatty acids in sebum from sebaceous glands
➢ Extracellular antimicrobial lipids; ceramide & sphingosine
➢ Acid pH (3-5) of sweat (lactic acid)
➢ Antimicrobial peptides
e.g. dermcidin in sweat
from eccrine glands

Question 10

what do epithelial tight junctions help to do?

Answer 10

prevent infection

Question 11

where is mucus produced and how does it get to the larynx?

Answer 11

-by goblet cells in the epithelium and by mucus glands in the lower respiratory tract
-cilia in the lower respiratory tract move the mucus up toward the larynx

Question 12

what do epithelial cells produce?

Answer 12

antimicrobial peptides (defensins) and lysozymes

Question 13

what do symbiotic bacteria in the gut do?

Answer 13

-compete with pathogens for nutrients and sites of attachment

Question 14

what are the other external innate immune defences?

Answer 14

-The flow of tears, urine, saliva, perspiration, vaginal
secretions, to prevent microbe adhesion to epithelial
surfaces
* Lysozyme (muramidase) in tears,
saliva and mucus
* Defecation (diarrhea) and vomiting to expel
microbes
* Highly acidic gastric acid secretions (pH 1.2-3.0)
destroy bacteria and toxins.

Question 15

what are some internal cellular and chemical defences?

Answer 15

-the inflammatory response
-phagocytosis
-natural killer cells-cellular
-the complement system-cellular

Question 16

what do natural killer cells do?

Answer 16

-kill virally infected cells which
have abnormal proteins in the plasma membrane, by
releasing perforin (cytolysis) and granzymes (induce
apoptosis).
-Released microbes are killed by phagocytes.

Question 17

how do phagocytes act as a cellular defense?

Answer 17

-they have neutrophils and macrophages which are cells specialised to ingest and destroy microbes

Question 18

what are the different antimicrobial substances that act as chemical defences?

Answer 18

-interferons
-complement proteins
-iron binding proteins
-antimicrobial peptides

Question 19

give examples of interferons…

Answer 19

-IFNα,
-IFNβ
-IFNγ

Question 20

what do interferons do?

Answer 20

they are antiviral proteins that inhibit the replication of viruses in cells nearby and limit the spread of the virus

Question 21

what do complement proteins do?

Answer 21

when activates the promote bacterial cytolysis, phagocytosis and inflammation

Question 22

what do iron binding proteins do?

Answer 22

-examples are transferrin and lactoferrin and they inhibit the growth of iron dependent bacteria

Question 23

what do antimicrobial peptides include?

Answer 23

-dermcidin in sweat
-defences produced by epithelial cells
-neutrophils
-macrophages

Question 24

what happens in the complement innate defence?

Answer 24

-there is a biochemical cascade that helps the clearance of pathogens --it consists of a small number of proteins found in the blood -it is synthesised mainly by the liver and circulate s zymogens

Question 25

what is a consequence of compliment activation?

Answer 25

-the three complement pathways converge at the membrane attack complex (MAC)

Question 26

what is the importance of inflammatory responses?

Answer 26

-they provide immediate protection against tissue injuries and foreign substances-they are crucial for help and wellbeing -they cause visible systems and can rid the body of harmful of orgnsdimd

Question 27

what may result excessive inflammatory responses?

Answer 27

tissue damage

Question 28

what are the causes of acute inflammation?

Answer 28

-allergic reactions -chemical irritants -infection -trauma injury -burns -laceration,cuts,wounds -frostbite

Question 29

what are the causes of chronic inflammation?

Answer 29

-cardiovascular disease -neurological disease -autoimmune disease -rheumatoid arthiritis -cancer -lupus -fibromyalgia -chronic fatigue syndrome

Question 30

what are the stages of inflammation?

Answer 30

-vasodilation -increased vascular permeability -phagocyte emigration -tissue repair

Question 31

what are the symptoms of inflammation?

Answer 31

-redness (rubor) -heat(calor) -swelling (tumor) -pain(dolor)

Question 32

what are the mediators of vasodilation and increased vascular permeability?

Answer 32

-histamine released from mast cells activated by complement proteins (C3a and C5a) -bradykinin,prostaglandins and leukotrienes are also mediators and can affect nerve endings and cause pain

Question 33

what are the processes closely linked to the inflammatory responses?

Answer 33

-immune reactions -fever -wound healing

Question 34

what are the stages of a fever?

Answer 34

-some cytokines stimulate the brain to make prostaglandins (PGEs) -they stimulate the hypothalamus to a new temp set point -the signals the hypothalamus sends out then:constricts blood vessels in the skin, contract skeletal muscles and increases heart rate and respiration

Question 35

what is wound healing?

Answer 35

-the body replacement of destroyed tissue by living tissue -it can be achieved by two processes:tissue regeneration and scar formation

Question 36

what are the different phases of wound healing?

Answer 36

-inflammatory phase -profliferative phase -maturation phase

Question 37

what happens in the inflammatory phase of wound healing?

Answer 37

-a clot forms and cells of inflammation debride injured tissues

Question 38

what happens in the proliferative phase of wound healing?

Answer 38

-epithelialization,fibroplasia and angiogenesis occur, granulation tissue forms and the wound begins to contract

Question 39

what happens in the maturation phase of wound healing?

Answer 39

-collagen forms tight cross-links to other collagen and with protein molecules, increasing tensile strengths of the scar

Question 40

what is pus?

Answer 40

-pocket of dead phagocytes and damaged tissue that occurs at most sites of inflammation and persists until the bacteria is cleared -pus can drain externally or internally

Question 41

what line of defence is adaptive immunity?

Answer 41

third line

Question 42

what are the key features of adaptive immunity?

Answer 42

-specificity-for particular foreign molecules (antigens=antibody regulators) -memory-for most previously encountered antigens, so that the second encounter stimulates a faster and greater response

Question 43

what do activated cytotoxic T-cells do?

Answer 43

-recognise and bind to infected cells displaying the specific antimicrobial antigen -perforin causes lysis of the infected cell and granulysin kills the microbe -granzymes induce apoptosis

Question 44

how are B-cells activated?

Answer 44

-by direct recognition of an antigen through B-cell receptors or through T-helper cell activation

Question 45

what do activated B-cells undergo?

Answer 45

clonal expansion to become antibody producing plasma cells

Question 46

what are the 5 different classes of antibodies?

Answer 46

-IgG -IgA -IgM -IgE -IgD

Question 47

what is IgG?

Answer 47

a monomer that is the most abundant antibody in the blood, it neutralises bacterial and viral toxins, enhances phagocytosis and activates complement -it crosses the placental fetal immunity

Question 48

what is IgA?

Answer 48

a dimer that is the most abundant antibody in sweat, tears,saliva,mucus,milk and protects mucus membranes against the adhesion of virus and bacteria

Question 48

what is IgM?

Answer 48

-a pentamer and the first antibody to be secreted by plasma cells following activation -it activates complement, causes agglutination and lysis of bacteria-antibodies to blood group antigens are IgM

Question 49

what is IgE?

Answer 49

a monomer, mostly found on mast cells in tissue and involved in allergic reactions and acts as defence against parasites

Question 49

what is IgD?

Answer 49

a monomer found on the surface of B-cells as an antigen receptor

Question 50

what is the immunological memory?

Answer 50

-where thousands of memory cells exist after initial encounter with an antigen -with the next appearance of the same antigen, memory cells can proliferate and differentiate within hours -serum IgG antibody titers are much higher and faster on the second response

Question 51

how do vaccinations leverage the adaptive immunity system?

Answer 51

by introducing antigens to stimulate antibody production and memory cell formation providing long term protection