immunology 1,2

Question 1

describe the main first line defence mechanisms

Answer 1

(physical and anatomical barriers)

respiratory and GI tract- mucous membranes, protective barrier prevents microbes attaching

skin- stratum corneum (outer layer of epithelial cells), contains insoluble keratin, thick layer, waterproof

skin glands- sweat flushes out microbes, temp regulation

tears/blinking- flushes eye surface to clear pathogens, keeps surface moist

nasal hair- traps particles, makes air warm for lungs

saliva- captures/carries microbes to stomach

ciliated epithelium- moves foreign particles from trachea and bronchi to pharynx for removal

reflexes- sneezing, vomiting, coughing, defecation, ejects foreign material

human microbiota- prevents harmful microbes from forming

(non specific chemical defences)

specialised glands- sebaceous glands in skin and meibomian glands secrete sebum with antimicrobial effect

lysosymes and defensins in tears and saliva- hydrolyse peptidoglycan in bacteria, defensins are peptides that damage cell membrane and bacteria/fungi

skins acidic pH and fatty acid content- prevents harmful microbes colonising while good microbes are allowed

sweat- high lactic acid conc, unfavourable to many microbes, temp regulation, maintains pH, allows good microbes

Question 2

what is the lymphatic system

Answer 2

network of vessels/accessory organs that return extracellular fluid to circulation and carries out immune surveillance via lymphocytes and phagocytes

Question 3

what does lymph contain

Answer 3

extracellular fluid, WBCs, fats, cell debris

Question 4

what do lymph vessels do

Answer 4

move fluid from tissue to heart using contractions of surrounding skeletal muscle

Question 5

name primary and secondary lymphatic organs

Answer 5

primary= thymus gland and bone marrow

secondary= spleen, lymph nodes, MALT, GALT, SALT

Question 6

what is MALT GALT and SALT

Answer 6

mucosal associated lymphoid tissue
gut
skin

Question 7

another name for white blood cells

Answer 7

leukocytes

Question 8

two types of leukocytes

Answer 8

granulocytes- neutrophils, basophils, eosinophils, lobed nuclei, cytoplasmic granules, aid diagnosis, neutrophils most abundant

agranulocytes- monocytes, lymphocytes, globular and non lobed nuclei, lack notable granules, monocyte differentiate into macrophages and dendritic cells

Question 9

what are PRRs

Answer 9

pattern recognition receptors
displaced on WBC membrane and senses/interacts with pathogens, not microbe specific

Question 10

what are PAMPs

Answer 10

pathogen associated molecular patterns
shared by pathogens, acts as warning, activates downstream signalling

Question 11

what is the aim of immune system

Answer 11

prevent harmful microbes and pathogens entering body

Question 12

what is innage defence

Answer 12

natural defences present at birth, non specific resistance to infection

Question 13

what is innate defence divided into

Answer 13

first line defence=blocks invasion at entry site (surface barriers like skin, mucous, membranes)

second line defence=non specific phagocytes, internal systems, chemicals (phagocytosis, fevers, inflammation)

Question 14

what is haematopoiesis

Answer 14

production of RBCs WBCs and platelets in bone marrow

Question 15

what is inflammation and its characteristics

Answer 15

process to restore homeostasis, after injury or trauma in tissues, after infection or tissue death, symptom of allergy, redness from vasodilation, warmth from increased blood circulation, swelling from increased ECF, pain from stimulated nerves by pressure and chemicals, can cause loss of function

Question 16

function of inflammation

Answer 16

clear invading microbes and cell debris after immune reactions, attract immune cells and chemical mediators, start repair mechanisms, destroy/block microbes

Question 17

what are cytokines, what are they produced by, what do they do

Answer 17

complex group of signalling molecules, produced by helper T cells (WBCs), important for downstream actions and communications between innate and acquired immune mechanisms

Question 18

what are chemokines

Answer 18

type of cytokines that attract cells to infection sites

Question 19

what is chemotaxis and when does it occur

Answer 19

WBC migration, happens in response to inflammatory chemotactic factors, leaves circulation to reach target tissue

Question 20

how does chemotaxis occur

Answer 20

1. adheres to small blood vessel walls-adhesive receptors line endothelial cells, increased adhesion in response to cytokines
2. migrate to tissue via diapedesis-motile circulatory WBC change shape and leave vessel to enter extracellular matrix

Question 21

name the 3 major stages of phagocytosis

Answer 21

1. survey- patrol tissue, investigate foreign invaders/dead cells
2. ingest- engulf, eliminate unwanted
3. extract- process antigens from pathogens

Question 22

what is TLR and their functions

Answer 22

toll like receptors
-recognise PAMPs, trap foreign molecules, engulf, release chemical signs

Question 23

how do TLRs interact with pathogens

Answer 23

TLR joins together in pairs (dimerise) and captures foreign molecules and stimulates phagocytosis, pseudopods extend and encase particle in phagosome, lysosome within cell migrate and fuse with phagolysosome/vacuole, release of antimicrobial chemicals including digestive enzymes form lysosomes

Question 24

what are iterferons (IFN) and the different types

Answer 24

IFN=cytokine produced by WBC, antiviral and anticancer activity

interferon alpha=from macrophages and lymphocytes
beta=epithelial cells and fibroblasts
gamma=T cells

Question 25

functions of interferons

Answer 25

stimulate phagocytes/phagocytosis, regulate macrophages and lymphocyte/T and B cells, bind to cell surface and trigger changes in gene expression, inhibits gene tumour suppressor, activate natural killer cells

Question 26

what is the complement system

Answer 26

(part of immune system that cleans up damaged cells, helps your body heal after an injury or an infection and destroys microscopic organisms like bacteria)

protein cascade triggered by specific recognition molecules and progressing through a series of protein protein interactions that culminate in formation of a cytolytic pore

Question 27

where are complement proteins produced

Answer 27

liver

Question 28

name the 3 main complement system pathways and what initiates them

Answer 28

classical- initiated by antibody antigen complexes, connected to acquired third line defence

lectin- initiated by pattern recognition molecules binding to PAMPs

alternative- initiated by microbes in absence of antibody

Question 29

3 key features of complement system

Answer 29

1. membrane attack complex (MAC)-proteins activate reactions, C9 units bind to complex, can kill eukaryotic and bacterial pathogens, C3 converts to C3b and 3a, C5→C5b and C5a, C5b combines with C6,7,8, C3a and 5a stimulate mast cell degranulation, chemotaxis and inflammation
2. opsonisation- coating pathogens and labels for phagocytosis
3. cytokine release and cell recruitment- promotes further signalling, heightened immune response aide by C3a and C5a

Question 30

what does PAMP stand for

Answer 30

pathogen associated molecular patterns