Intro to immunology

Question 1

What are the classes of pathogens?

Answer 1

Extracellular bacteria, parasites, fungi; intracellular bacteria, parasites; intracellular viruses; extracellular parasitic worms

Question 2

What are the two general ways that pathogens enter the body?

Answer 2

Through mucosal surfaces and external epithelia

Question 3

What are the three types of mucosal surfaces where pathogens can enter?

Answer 3

Airways, GI tract, reproductive tract

Question 4

How do pathogens enter the airways?

Answer 4

Inhaled droplets, spores

Question 5

How do pathogens enter the GI tract?

Answer 5

Contaminated water or food

Question 6

How do pathogens enter the reproductive tract?

Answer 6

Physical contact

Question 7

How do pathogens enter through external epithelia?

Answer 7

Through the external surface, wounds and abrasions, and insect bites

Question 8

How do pathogens enter through the external surface?

Answer 8

Physical contact

Question 9

What wounds and abrasions allow pathogens to enter the body?

Answer 9

Minor skin abrasions, puncture wounds, and handling infected animals

Question 10

What insect bites can allow pathogens to enter the body?

Answer 10

Mosquito bites (Anopheles and Aedes aegypti), and deer tick bites

Question 11

What are the two branches of immunity?

Answer 11

Innate and adaptive

Question 12

What is the identifying features of the innate immunity?

Answer 12

Most components present prior to infection; non-specific; fast; similar response each time

Question 13

How rapidly does the innate immunity act?

Answer 13

Within 0-4 hours

Question 14

How does the innate immunity act (very broad summary)?

Answer 14

Infection recognised by pre-formed, non-specific and broadly specific effectors; infectious agent removed

Question 15

What are the four levels of barriers in innate immunity?

Answer 15

Structural/physical barriers; chemical/physiological barriers; inflammatory barriers; phagocytic barriers

Question 16

What are the physical barriers?

Answer 16

Skin and mucous membranes

Question 17

How does the skin act as a barrier?

Answer 17

Mechanical barrier retards entry; pH 3-5 retards growth of microbes

Question 18

How do mucous membranes acts as barriers?

Answer 18

Normal flora of bacteria compete w/ microbes for attachment sites and nutrients; mucus traps foreign material and cilia propels out of body

Question 19

What are the chemical/physiological barriers?

Answer 19

Temperature, low pH, chemical mediators

Question 20

How does temperature act as barrier?

Answer 20

Body temperature inhibits pathogen growth; fever response inhibits pathogen growth

Question 21

How does low pH act as barrier?

Answer 21

Acidity of stomach (pH 1-2) kills most microbes

Question 22

How do chemical mediators act as barriers?

Answer 22

Complement is a series of protest than bind to and punch holed in cell membranes of microbes/infected self-cells

Question 23

Outline process of inflammation (brief).

Answer 23

Leakage of fluid from blood containing antibacterial proteins; influx of phagocytic cells; swelling; increased blood flow; increased local temperature. Prevents growth of microbes

Question 24

How do phagocytes act as barriers?

Answer 24

Cells endocytose and break down foreign macromolecules; monocytes, neutropils and tissue macrophages phagocytose, kill and digest microbes

Question 25

How do macrophages destroy pathogens?

Answer 25

Macrophage expresses receptors for many bacterial constituents; bacteria binds to macrophage; release of cytokines and small lipid mediators of inflammation initiated; macrophages engulf and digest bacteria

Question 26

What are the five classes of phagocytic mechanism?

Answer 26

Acidification; toxic oxygen derived products; toxic NOs; antimicrobial peptides; enzymes; competitors

Question 27

What are examples of antimicrobial peptides?

Answer 27

Defensins; cationic proteins

Question 28

What are examples of enzymes which aid destruction of pathogens?

Answer 28

Lysozyme: dissolves cell walls of some Gam +ve bacteria; acid hydrolases: further digest bacteria

Question 29

What role do cytokines play in innate immunity?

Answer 29

Signalling chemicals of the immune system; mediate inflammation; attract and activate other immune cells

Question 30

What are the identifying features of adaptive immunity?

Answer 30

Specific; slower response; memory property which enables much quicker and vigorous second response

Question 31

How does the second encounter with a pathogen produce a much more rapid response?

Answer 31

Recognition of microbial-associated molecular patterns allows rapid inflammation recruitment and activation of effector cells

Question 32

What are the four characteristic attributes of adaptive immunity?

Answer 32

Antigenic specificity; diversity; immunological memory; self/non-self recognition

Question 33

What is antigenic specificity?

Answer 33

Can distinguish between antigens differing by only one amino acid

Question 34

What are the three classes of cells involved in the adaptive immunity?

Answer 34

Antigen presenting cells; T-cells; B-cells

Question 35

What are the two types of T-cells?

Answer 35

T-helper; cytotoxic T cell

Question 36

What do T-helper cells do?

Answer 36

Secrete cytokines to attract other T-cells; constant immune-surveillance by circulating blood and lymph; target virally infected body cells and those which have undergone a malignant transformation; recognise foreign or altered self-peptide expressed by MHC class-I molecules

Question 37

What do cytotixuc T cells do?

Answer 37

Kill virus infected/ cancer cells

Question 38

What do B-cells do?

Answer 38

Encounter antigen and divide into memory and plasma cells

Question 39

What cells produce antibodies?

Answer 39

Plasma cells; produce >2000 antibody molecules

Question 40

How does the body respond to viral infection?

Answer 40

Macrophage in tissues picks up viral particle released from infected cell; antigen processed and presented outside of cell (APC); macrophage releases signalling molecules; attracted T helper recognises antigen; T helper activated; T helper releases inflammatory cytokines; cytotoxic T cells activated and recognise infected body cells; infected body cell killed

Question 41

What are the two types of cytotoxic cells?

Answer 41

Cytotoxic T cells (adaptive immunity); natural killer cells (innate immunity)

Question 42

How do cytotoxic cells kill infected cells?

Answer 42

Cytotoxic cells contain granules; granules filled with potent chemicals; cytotoxic cells bind with target cells; chemicals lyse infected cell; punch holes in membranes of cell; proteases enter infected cell. T cells can also trigger apoptosis (normal cell death pathways)

Question 43

How do antibodies kill pathogens?

Answer 43

Toxins neutralised by antitoxins and ingested by macrophages; extracellular bacteria opsonised by antibodies and ingested by macrophages; plasma bacteria lysed by complementary antibodies and ingested

Question 44

What are the primary organs of the immune system?

Answer 44

Thymus, bone marrow

Question 45

What are the secondary organs of the immune system?

Answer 45

Tonsils and adenoids; lymph nodes and vessels; spleen, Peyer’s patches; appendix

Question 46

How are cells of the immune system identified and described?

Answer 46

Using CD numbers (cluster of differentiation) = numbers assigned to proteins expressed on the surface of cells

Question 47

What cells “bridge the gap” between innate and adaptive immunity?

Answer 47

Dendritic cells

Question 48

What are the four types of immunity possible?

Answer 48

Active natural (immune response); active artificial (vaccines); passive natural (breastfeeding); passive artificial (anti-venom)

Question 49

How does psychological stress affect immunity?

Answer 49

Acute psychological stress enhances immunity, but chronic suppresses immunity

Question 50

How does exercise affect immunity?

Answer 50

Acute exercise enhances immunity, and regular exercise improves immunity

Question 51

How does the immune system respond to exercise?

Answer 51

Specific cells are selectively mobilised during exercise (lymphocytosis) due to shear stress and increased catecholamines decreasing adherence to vasculature, as well as mobilisation from spleen and bone marrow to repair minute injuries; specific cells preferentially leave circulation after exercise (lymphocytopenia)