organisation of the immune system

Question 1

what are the primary lymphoid organs

Answer 1

bone marrow, thymus

Question 2

what is the function of primary lymphoid organs

Answer 2

production of lymphocytes (lymphopoiesis)

Question 3

what are the secondary lymphoid organs

Answer 3

spleen, lymph nodes, mucosal associated lymphoid tissue (MALT)

Question 4

what is the function of secondary lymphoid organs

Answer 4

where lymphocytes can interact with antigen and other lymphocytes

Question 5

features of thymus

Answer 5

bi-lobed, lobules packed with lymphocytes

Question 6

staining distinction of medulla and cortex of thymus

Answer 6

medulla not very stained, cortex very stained

Question 7

what is the septa divided into in the thymus

Answer 7

lobes, then lobules

Question 8

where do Treg cells develop within the thymus

Answer 8

Hassall’s corpuscle (whirl of fibroblasts)

Question 9

what happens to the thymus during infection

Answer 9

no obvious change in appearance

Question 10

why does thymic output decline with age

Answer 10

size decreases, becomes more fatty (same number of cells but reduced specificity, becoming oligoclonal); more memory cells

Question 11

what is red bone marrow the site of

Answer 11

haematopoiesis

Question 12

what happens in bone marrow during infection

Answer 12

white blood cell production increases

Question 13

what is present in yellow bone marrow

Answer 13

fat

Question 14

where is bone marrow present in foetuses

Answer 14

all bones, liver, spleen

Question 15

characteristic of foetal bone marrow

Answer 15

very cellular

Question 16

where is bone marrow present in adults

Answer 16

mostly flat bones, vertebrae, iliac bones, ribs, ends of long limb bones

Question 17

characteristic of adult bone marrow

Answer 17

marrow and fat

Question 18

how much lymph is returned to the superior vena cava each day

Answer 18

2-3 litres

Question 19

what do the lymph nodes do

Answer 19

filter for antigens in the blood

Question 20

where are the B and T cell areas located in the lymph nodes

Answer 20

B cells are outer, T cells are inner

Question 21

what do B lymphocytes aggregate into in lymph nodes

Answer 21

follicles

Question 22

what happens to B lymphocytes in lymph nodes during infection

Answer 22

rapidly proliferate, forming a germinal centre, swelling the lymph node

Question 23

during immune stimulation of activated B cells in germinal centres of the lymph nodes, how are antigen-specific repertoire of lymphocytes modified

Answer 23

somatic mutations

Question 24

what is the function of the spleen

Answer 24

filter for antigens in the blood

Question 25

what is the function of the red pulp in the spleen

Answer 25

turnover or red blood cells removed through reticulo-endothelial system

Question 26

what is the function of the white pulp in the spleen

Answer 26

location of lymphocytes surrounding blood vessels

Question 27

what brings blood into the spleen

Answer 27

splenic artery

Question 28

what is the main T cell area in the spleen

Answer 28

periarterial lymphatic sheath (PALS)

Question 29

what is the main B cell area in the spleen

Answer 29

primary follicle

Question 30

what is produced if there is an ongoing immune response in the spleen

Answer 30

germinal centres

Question 31

what is the body vulnerable to if there is no spleen

Answer 31

encapsulated bacteria

Question 32

why is the epithelium heavily defended

Answer 32

large surface area, in some places one cell thick

Question 33

two lymphoid tissues near epithelium

Answer 33

mucosa-associated lymphoid tissue (MALT), cutaneous immune system

Question 34

components of gut-associated lymphoid tissue (GALT)

Answer 34

T and B cell areas, follicles, germinal centres, villi (containing draining lymph vessels), M (microfold) cells, Peyer's patch

Question 35

function of M cells in epithelium

Answer 35

samples antigens from gut and delivers them to lymphocytes in Peyer's patch

Question 36

what is located in the Peyer's patch in epithelium

Answer 36

predominantly B lymphocytes, contains germinal centres

Question 37

components of cutaneous immune system in epithelium

Answer 37

epidermis, dermis

Question 38

what is present in the epidermis of the cutaneous immune system in the epithelium, and what is their function

Answer 38

keratinocytes (detect damage to skin), Langerhans cells (type of dendritic cell), intraepidermal lymphocytes

Question 39

what is present in the dermis of the cutaneous immune system in the epithelium

Answer 39

T lymphocytes, macrophages, dermal dendritic cells

Question 40

function of cutaneous immune system in epithelium

Answer 40

capture antigens in local environment