Lymphoid tissue (year 2)

Question 1

what are lymphoid tissues?

Answer 1

organs in which lymphocytes are produced, matured and differentiated

Question 2

what happens at primary lymphoid tissue?

Answer 2

lymphocytes are generated and matured

Question 3

what happens at secondary lymphoid tissue?

Answer 3

lymphocytes interact with antigen presenting cells (APCs)

Question 4

list the main primary lymphoid tissue

Answer 4

bone marrow, thymus gland, bursa of fabrics, ileal payers patch, appendix (rabbits)

Question 5

list the main secondary lymphoid tissue

Answer 5

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

Question 6

where is the thymus found?

Answer 6

thoracic organ near the heart

Question 7

what happens at the thymus?

Answer 7

T lymphocyte maturation and selection

Question 8

what happens to the thymus as you age?

Answer 8

atrophies and produces fewer T cells

Question 9

how is the structure of the thymus divided?

Answer 9

outer capsule, cortex, medulla

Question 10

describe the arrangement of the structure of the thymus’ cortex

Answer 10

densely populated with lymphocytes of various size with some macrophages to remove thymocytes that have undergone apoptosis

Question 11

what are thymocytes?

Answer 11

immature lymphocytes

Question 12

what happens to thymocytes in the cortex of the thymus?

Answer 12

they mature and migrate to the medulla

Question 13

describe the arrangement of the medulla of the thymus

Answer 13

less densely populated as the cells begin to die

Question 14

what happens in the medulla of the thymus?

Answer 14

antigen is presented to the lymphocytes they undergo thymus selection and pass into circulation

Question 15

what is the aim of the process that happens in the thymus?

Answer 15

remove self-reactive T-lymphocytes, these cells will cause autoimmunity if not removed

Question 16

describe the passage of cells through a lymph node

Answer 16

enter through afferent vessel travel through the cortex then medulla and out through the efferent vessel

Question 17

what does the cortex of lymph nodes mainly contain?

Answer 17

B cells

Question 18

what does the paracortex of lymph nodes contain?

Answer 18

T cells

Question 19

what does the medulla of lymph nodes contain?

Answer 19

T and B cells

Question 20

what do medullary cords of lymph nodes contain?

Answer 20

macrophages and plasma cells

Question 21

what are germinal centres in lymph nodes?

Answer 21

clusters of proliferating lymphocytes (T or B) that are proliferating in response to an antigen - these cause lymph nodes to expand or contract

Question 22

describe the route of mature lymphocytes around the body

Answer 22

blood lymphocytes drain into tissue which then drains via an afferent vessel into lymph nodes and back out via the efferent vessel. From here they then enter the thoracic duct where they make their way back to the blood lymphocyte pool

Question 23

describe the route of immature lymphocytes around the body

Answer 23

drain straight from blood via high endothelial venues bypassing the tissue and afferent vessels

Question 24

what are high endothelial venules?

Answer 24

tall rounded endothelial cells that are post capillary venues only found in secondary lymphoid tissue

Question 25

when do high endothelial venules increase in numbers?

Answer 25

following antigen stimulation

Question 26

what are two main structures of the spleen?

Answer 26

red and white pulp

Question 27

what is red pulp in the spleen?

Answer 27

open sinusoids containing red blood cells

Question 28

what is white pulp in the spleen?

Answer 28

mainly lymphocytes

Question 29

how does the spleen provide systemic immunity?

Answer 29

has a large blood flow

Question 30

where can mucosal associated lymphoid tissue be found?

Answer 30

GI tract
respiratory tract
genito-urinary tract
peters patches
appendix
tonsils

Question 31

what are MALT?

Answer 31

dense areas of lymphocytes and macrophages that don’t have a capsule or afferent lymphatic vessels

Question 32

describe the structure of MALT

Answer 32

no capsule
no afferent lymphatic vessel
have lymphoid follicles
have germinal centres

Question 33

where are peters patches found?

Answer 33

in ideal submucosa of small bowel

Question 34

what do payers patches detect?

Answer 34

antigens that diffuse across intestinal epithelia via M-cells