Lymphatics

Question 1

innate immune system

Answer 1

non-specific immunity

Question 2

adaptive immune system

Answer 2

specific immunity

Question 3

primary lymphoid organs

Answer 3

thymus and bone marrow

Question 4

secondary lymphoid organs

Answer 4

spleen, lymph nodes and MALT

Question 5

what are natural killer cells

Answer 5

they kill virus-infected cells and some tumor cells

Question 6

what do B-lymphocytes do

Answer 6

produce antibodies (humoral immunity)

Question 7

what do T-lymphocytes do

Answer 7

participate in cellular immunity

Question 8

subsets of T-Lymphocytes

Answer 8

T-helper cells, Cytotoxic T cells, Suppressor T cells

Question 9

supporting cells of the lymphatic system

Answer 9

antigen-presenting cells, epithelial cells, stromal cells, leukocytes

Question 10

what do cytotoxic T cells do

Answer 10

kill virus-infected and some cancer cells, requiring interaction with helper cells to activate and proliferate to form clones of effector cells

Question 11

what do T helper cells do

Answer 11

they use mediators known as interleukins to provide assistance to B cells, cytotoxic T cells and macrophages

Question 12

what do suppressor T cells do

Answer 12

may suppress immune responsiveness to self-antigens and possibly switch off the response when antigen is removed

Question 13

what do memory T cells do

Answer 13

provide a rapid reaction force for a subsequent encounter with the same antigen

Question 14

what lymphocytes develop in the bone marrow

Answer 14

B lymphocytes and natural killer cells

Question 15

location of the thymus

Answer 15

anterior mediastinum

Question 16

cells of the connective tissue septa of the thymus

Answer 16

epithelioreticular cells

Question 17

the main change of the thymus from an infant to an adult

Answer 17

the lymphoid tissue is replaced with adipose tissue

Question 18

contents of the darkly staining cortex

Answer 18

large numbers of T cells, epithelioreticular cells, macrophages

Question 19

contents of the lightly staining medulla

Answer 19

T cells (larger and less densely packed), epithelioreticular cells, Hassall’s corpuscles

Question 20

life cycle of a T cell

Answer 20

positive selection in the cortex -> negative selection in the medulla -> enter the bloodstream

Question 21

what are thymic nurse cells

Answer 21

form part of the blood-thymus barrier in the cortex, invested by basal lamina, with cytoplasmic processes linked by desmosomes that create a physical barrier protecting the immature lymphocytes from blood-borne antigens

Question 22

contents of an epithelial reticular cell

Answer 22

lysosomes, electron-dense granules and tonofilaments

Question 23

what are lymph vessels

Answer 23

thin-walled, endothelially-lined vessels that look similar to capillaries but lack a basal lamina

Question 24

common locations of lymph vessels

Answer 24

dermis of skin, liver, beneath mucous membranes of the respiratory, genitourinary and gastrointestinal tracts

Question 25

what do lymph vessels do

Answer 25

interstitial fluid and wandering lymphocytes are taken up by lymphatic vessels and added back to the circulation

Question 26

lymphatic drainage order

Answer 26

lymphatic vessels -> thoracic duct -> subclavian veins

Question 27

what tissue do lymph nodes derive from

Answer 27

mesenchyme

Question 28

composition of a lymph node

Answer 28

capsule, cortex, para-cortex, medulla, and subcapsular sinus

Question 29

structures present at the hilum of a lymph node

Answer 29

small artery, small vein and afferent and efferent lymphatic vessels

Question 30

afferent lymphatic vessels

Answer 30

lymph enters the node

Question 31

efferent lymphatic vessels

Answer 31

lymph exits the node

Question 32

main functions of a lymph node

Answer 32

filtration, production of lymphocytes, synthesis of antibodies (mainly IgG) and recirculation of lymphocytes

Question 33

contents of the cortex of lymph nodes

Answer 33

lymphoid nodules occupied by B cells

Question 34

contents of the para-cortex of lymph nodes

Answer 34

T cells

Question 35

primary lymphoid nodules

Answer 35

spherical aggregates of tightly packed B cells in a network of reticular fibres

Question 36

secondary lymphoid nodules

Answer 36

have a germinal center containing actively dividing B cells and a mantle zone surrounding containing resting B cells

Question 37

what occurs in the para-cortex

Answer 37

antigen-dependent T cell differentiation and proliferation

Question 38

contents of the medulla of the lymph node

Answer 38

loosely arranged lymphoid tissue, medullary cords consisting of lymphocytes, macrophages, and plasma cells, medullary sinuses, and irregularly arranged trabeculae

Question 39

flow of lymph in a lymph node

Answer 39

delivered to the subcapsular sinus -> trabecular sinus -> medullary sinus -> exits via efferent vessels at hilum

Question 40

what cells occupy the para-cortical region of a lymph node

Answer 40

T cells

Question 41

lining of high endothelial venules in lymph nodes

Answer 41

cuboidal epithelium

Question 42

what are high endothelial venules

Answer 42

specialized venules for passage of B and T cells by selective diapedesis from the blood into perivascular areas

Question 43

morphology of high endothelial venules

Answer 43

cuboidal endothelial cells, prominent perivascular sheath, thick basal lamina

Question 44

what is homing

Answer 44

the movement of B and T cells across high endothelial venules into lymph nodes and other sites

Question 45

what lymphoid organ lacks high endothelial venules

Answer 45

the spleen

Question 46

evolution of B cells

Answer 46

naive B cell -> small centrocyte -> large centrocyte -> small centroblast -> large centroblast -> immunoblast -> memory B cell or plasma cell

Question 47

divisions of MALT

Answer 47

GALT, NALT, BALT and VALT

Question 48

what is MALT characterized by

Answer 48

lymphocyte infiltrations, which are not sharply delineated from surrounding CT but are supported loosely by reticular fibres

Question 49

main immunoglobin formed in MALT

Answer 49

IgA produced by plasma cells

Question 50

what type of cell is abundant in the dome of Peyer's patches

Answer 50

M cells

Question 51

what are palatine tonsils

Answer 51

organized masses of lymphoid tissue which, alongside lingual, pharyngeal, and tubal tonsils, form Waldeyer's ring

Question 52

lining of the liminal palatine tonsil

Answer 52

stratified squamous epithelium

Question 53

what separates the base of the tonsil from the underlying muscle

Answer 53

dense collangenous hemicapsule

Question 54

what does the tonsillar parenchyma contain

Answer 54

numerous lymphoid follicles with germinal centres similar to those found in lymph nodes

Question 55

blood supply to the spleen

Answer 55

splenic artery provides the spleen with a rich blood supply

Question 56

blood drainage of the spleen

Answer 56

splenic vein drains the blood from the spleen into the hepatic portal artery

Question 57

main functions of the spleen

Answer 57

production of immunological responses against blood-borne antigens, removal of particulate matter or defective blood cells from circulation, and hematopoiesis in the normal fetus

Question 58

what does the structure of the spleen allow

Answer 58

intimate contacts to be made between the blood and lymphocytes

Question 59

histology of the spleen

Answer 59

capsule, trabeculae, white pulp and red pulp

Question 60

what is white pulp

Answer 60

greyish-white islands of lymphoid tissue, most surrounding a central arteriole and forming a periarteriolar lymphoid sheath

Question 61

where is the central arteriole in a PALS derived from

Answer 61

the splenic artery

Question 62

where do lymphoid nodules lie in white pulp relative to the arterioles

Answer 62

peripherally

Question 63

what is surrounding white pulp

Answer 63

a shell of sparsely cellular lymphoid tissue - the marginal zone - that contains macrophages and B lymphocytes

Question 64

what is red pulp

Answer 64

it makes up a majority of the spleen and contains abundant erythrocytes

Question 65

what occupy the cords of Bilroth in the spleen

Answer 65

reticular cells, lymphocytes, plasma cells and macrophages, alongside all formed elements of circulating blood

Question 66

what is a cord of Bilroth

Answer 66

splenic cords which are reticular tissue rich in lymphocytes

Question 67

what is a stave cell

Answer 67

an unusual endothelial cell with an incomplete basement membrane