1. Tissues of the Immune System

Question 1

Primary lymphoid organs examples

Answer 1

Thymus and bone marrow

Question 2

Secondary lymphoid organs examples

Answer 2

Spleen, lymph nodes, mucosal associated (MALT, GALT, BALT)

Question 3

What does the B in B cells indicate?

Answer 3

Cells derived from Bursa (first seen in birds) equivalent tissues (of which includes bone marrow and foetal liver)

Question 4

What are primary lymphoid tissues?

Answer 4

Involved in development and differentiation of lymphocytes

Question 5

What are secondary lymphoid tissues?

Answer 5

Where antigens and lymphocytes accumulate and are brought together to bind

Question 6

What are tertiary lymphoid tissues?

Answer 6

Maybe invaded by unique subsets of memory lymphocytes during inflammation

Question 7

Tertiary lymphoid organs examples

Answer 7

Skin

Question 8

What is the structure of the thymus?

Answer 8

Two lobes divided into smaller lobules by trabeculae. Each lobule has an outer cortex and inner medulla. Gets smaller with age

Question 9

What is thymocyte development affect by?

Answer 9

Thymus nurse cells

Question 10

What are naive lymphocytes?

Answer 10

Lymphocytes that have not yet met their antigen

Question 11

What happens to thymocytes that recognise self cells?

Answer 11

Apoptosed and cleaned up by Hassall’s corpuscles

Question 12

What specifically do TCRs bind to?

Answer 12

foreign molecules that have been broken down into smaller peptides and presented via the MHC

Question 13

process of t cell differentiation

Answer 13

double negative (do not express either CD4 or 8) then double positive and then either. CD3 and TCR expression also increases as it matures. takes 1-3 weeks

Question 14

what do BCRs bind to?

Answer 14

the whole pathogen

Question 15

lymphatic system

Answer 15

vessels of extracellular fluid. how lymphocytes and leukocytes move throughout the body

Question 16

how do lymphocytes move throughout the blood?

Answer 16

bind to adhesion molecules on endothelial cells and roll along the vessel

Question 17

efferent pathway

Answer 17

exit - out of the lymphatic system via the thoracic duct

Question 18

afferent pathway

Answer 18

arrival - into the lymphatic system via HEV

Question 19

lymphocyte homing

Answer 19

migration - the traffic of cells through the body to specific areas

Question 20

lymph nodes structure

Answer 20

small, bean-shaped, tissue aggregates at junctions of major lymphatic vessels, surrounded by a capsule & supported by a reticulum

Question 21

what are the three main areas of lymph nodes?

Answer 21

cortex, paracortical area, medulla

Question 22

HEV

Answer 22

high endothelial venules

Question 23

where do t and b cells collect in the lymph nodes?

Answer 23

t - paracortical

b - outer cortex (bind to antigens first since don’t need breaking down)

Question 24

paracortical area

Answer 24

contains antigen presenting cells and large lymphocytes

Question 25

medulla

Answer 25

contains plasma secreting antibodies

Question 26

primary vs secondary follicles

Answer 26

Primary follicles are very dense & uniform Secondary follicles contain larger cells associated with macrophages forming GERMINAL CENTRES with lots of cell proliferation

Question 27

what happens after antigen exposure in lymph nodes?

Answer 27

increased lymphocyte turnover

Question 28

why do lymph nodes swell during infection?

Answer 28

increased lymphocyte proliferation

Question 29

spleen structure

Answer 29

Capsule with fibrous partitions (SEPTAE)

Question 30

what are the two types of spleen tissue?

Answer 30

red and white pulp

Question 31

Red pulp

Answer 31

Non-immunological role - filters damaged or aged red cells

Question 32

White pulp

Answer 32

Immunological role – to develop immune | responses

Question 33

PALS

Answer 33

PERIARTERIOLAR LYMPHATIC SHEATH - makes up white pulp of spleen, populated with T lymphocytes

Question 34

spleen b-dependent area

Answer 34

lymphoid follicles

Question 35

spleen t-dependent area

Answer 35

PALS

Question 36

Examples of MALT

Answer 36

GALT and BALT

Question 37

Structure of GALT

Answer 37

Peyer’s patches and isolated follicles in colonic submucosa, clusters/intraepithelial lymphocytes

Question 38

Peyer's patches

Answer 38

Aggregates of lymphocytes; B cells form central follicle surrounded by T cells & macrophages/antigen presenting cells, covered by microfold cells

Question 39

microfold cells

Answer 39

selectively takes up antigens to deliver them to lymphoid follicles

Question 40

BALT structure

Answer 40

consists of collections of mostly B cells organised into aggregates & follicles with few germinal centres, some M cells but organisation is less defined