Lymphatic tissue and organs Flashcards Preview

Year 1 Cell Biology > Lymphatic tissue and organs > Flashcards

Flashcards in Lymphatic tissue and organs Deck (68):
1

What are the primary lymphatic tissues?

1. Bone marrow2. Thymus

2

What occurs at primary lymphatic tissues?

Development and maturation of lymphocytes into immunocompetent cells

3

What are the secondary lymphatic tissues?

1. Lymph nodes2. Mucosa-associated lymphatic tissue (MALT)3. Spleen

4

What occurs at secondary lymphatic tissues?

Formation of immunological defense against antigens or pathogens; confrontation with antigens or pathogens

5

MALT consists of what other lymphatic regions?

1. GALT (gut-associated lymphatic tissue)2. BALT (bronchus-associated lymphatic tissue)3. GU tract4. Tonsils

6

In which layer of the epithelium is GALT located?

Lamina propria

7

What are characteristics of diffuse lymphatic tissue (MALT)?

1. Not sharply delineated2. Part of some other organ, often sprinkled through lamina propria3. Reticular fibers provide framework for cell suspension

8

Which cells are found in diffuse lypmhatic tissue?

Lymphocytes, monocytes, macrophages, plasma cells

9

What are characteristics of lymphatic nodules (follicles)?

1. Non-encapsulated, spherical, dense aggregations of lymphocytes with SOME organization2. May be primary or secondary3. May be solitary or aggregate structures

10

What are characteristics of primary lymphatic nodules?

Appear homogeneous throughout, have mostly small lymphocytes

11

What are characteristics of secondary lymphatic nodules?

Have two zones - corona (mantle) zone and germinal center

12

What is the mantle zone?

The outer, dark-staining zone containing mature (small) lymphocytes in a secondary lymphatic nodule

13

What is the germinal center?

The inner, light-staining zone containing immature (medium and large) lymphocytes in a secondary lymphatic nodule

14

What happens to a secondary lymphatic nodule when an antigen is encountered?

Germinal center starts to swell

15

Are solitary lymphatic nodules temporary or permanent?

Temporary - may appear and reappear at a particular site

16

Are lymphatic aggregates temporary or permanent?

Permanent

17

What are examples of lymphatic aggregates?

1. Peyer's patches in the ileum2. Lymphatic tissue in the appendix (lamina propria and submucosa)3. BALT in respiratory tract4. Lymphatic nodules in tonsils, lymph nodes, spleen

18

The tonsils have what kind of lymphatic tissue organization?

Aggregations of lymphatic nodules

19

What type of lymphocyte predominates in the tonsils?

B lymphocyte

20

What kind of epithelium covers the pharyngeal tonsils?

Pseudostratified columnar epithelium with cilia

21

Do the pharyngeal tonsils have crypts?

No

22

What do the pharyngeal tonsils have instead of crypts?

Pleats

23

What kind of epithelium covers the palatine tonsils?

Stratified squamous nonkeratinized infiltrated by B cells

24

Do the palatine tonsils have crypts?

Yes

25

Where are B cells produced in the palatine tonsils?

Germinal centers found in the nodules

26

What kind of epithelium covers the lingual tonsils?

Stratified squamous nonkeratinized

27

Do the lingual tonsils have crypts?

Yes

28

What are lymph node trabeculae?

CT septa that extend from capsule into lymph node carrying vessels and nerves

29

What are characteristics of subcapsular sinuses?

Deep to CT capsule, drain into trabecular sinuses

30

What are characteristics of trabecular sinuses?

1. Separate nodules from trabeculae2. Drain into medullary sinuses3. Lined by endothelial cells - allow lymphatic cells to enter or exit4. Contain reticular cells

31

Which lymph sinuses are lined by macrophages?

All sinuses

32

What are the cells of the reticular meshwork?

1. Reticular cells2. Dendritic cells3. Macrophages4. Follicular dendritic cells

33

What is the reticular tissue?

Consists of reticular cells and reticular fibers which form a fine 3D meshwork that suspends the cells and sinuses and supports lymph node contents

34

What is the function of the reticular cells?

Synthesize and secrete type III collagen. Cytoplasmic processes wrap around reticular fibers to isolate them from lymphatic tissue parenchyma

35

What is the function of dendritic cells in a lymph node?

Ag presentation

36

What is the function of macrophages in lymph nodes?

Ag presentation, phagocytic

37

What is the function of follicular dendritic cells in lymph nodes?

Bind Ag-Ab complexes

38

What comprises the parenchyma of a lymph node?

1. Cortex2. Paracortex3. Medulla

39

What type of lymphatic tissue organization is found in the cortex of the lymph node?

Nodules

40

What type of lymphocyte is found in the cortex of the lymph node?

B cell

41

What type of cells are found in the germinal center of the lymph node nodules?

Dendritic reticular cells

42

What type of lymphocyte is found in the paracortex of a lymph node?

T cell

43

Are nodules primary or secondary?

Secondary

44

Are nodules permanent or temporary?

Permanent

45

What part of the lymph node is thymus-dependent?

Paracortex

46

What are high endothelial venules?

1. Located in the paracortex2. Lined with simple cuboidal to columnar epithelium3. B and T cells escape from bloodstream via HEVs to enter paracortex (B cells keep going to cortex)

47

What percentage of lymphocytes enter the lymph node via the HEVs of the paracortex?

90%

48

What are medullary cords?

Irregularly shaped clumps of cells containing B, T, plasma, and dendritic cells and macrophages

49

What is the role of the thymus?

Site where T cells mature

50

In what part of the thymus do T cells mature?

Cortex

51

What type of cells form the framework of the thymus?

Epithelioreticular cells

52

What are the functions of Type 1 epithelioreticular cells?

1. Form seal around cortex to separate it from CT capsule and trabeculae2. Form sleeve around tunica adventitia of vessels3. Form tight junctions to seal thymic cortex from rest of the body

53

What is the function of Type 2 epithelioreticular cells?

1. Form meshwork in midcortex2. Held together by desmosomes3. "Teachers" of thymic cell education

54

What is the function of Type 3 epithelioreticular cells?

1. Protein synthesis2. Form tight junctions; seal between cortex and medulla

55

What is the function of Type 4 epithelioreticular cells?

Barrier at corticomedullary junction

56

What is the function of Type 5 epithelioreticular cells?

Meshwork / framework of medulla

57

What is the function of Type 6 epithelioreticular cells?

Form Hassall's corpuscles

58

What are Hassall's corpuscles?

Made of Type 6 epithelioreticular cells - they are concentric, eosinophilic whorls that are unique to thymic medulla. They exhibit keratinization

59

Where do mature T cells go once mature?

Enter bloodstream from medulla via postcapillary venules to take up residence in paracortex of lymph nodes and PALS of spleen

60

What makes up the blood-thymus barrier (inside-out)?

1. Endothelium2. Basal lamina3. Macrophages4. Type 1 epithelioreticular cells

61

What is DiGeorge's syndrome?

Individuals cannot produce T cells, may die from infection or tetany

62

Does the thymus have afferent lymphatic vessels?

No

63

What makes up the white pulp of the spleen?

1. Periarterial lymphatic sheath2. Splenic nodules

64

What are the characteristics of the periarterial lymphatic sheath?

1. Thymus-dependent zone of the splenic pulp2. Contains T cells3. Central artery is centrally located within PALS

65

What are the characteristics of the splenic nodules?

1. Lymphatic nodules2. Contain B cells3. May contain germinal center around central artery4. Central artery is eccentrically located in nodule

66

What makes up the red pulp of the spleen?

1. Splenic cords2. Splenic sinuses

67

What are the Cords of Billroth?

1. Irregular and branching cords of splenic tissue2. Contain loose network of reticular cells and fibers3. Spaces between fibers are filled with blood to be filtered4. Filter blood5. Contain macrophages, plasma cells, dendritic cells

68

What are the splenic sinuses?

1. Lined by endothelial cells with wide intercellular spaces to allow blood cells to pass in and out of sinuses2. Drain into pulp veins which in turn drain into trabecular veins