Lymphatic System I & II Flashcards Preview

Histology Post Midterm > Lymphatic System I & II > Flashcards

Flashcards in Lymphatic System I & II Deck (71):
1

How are the functions of the lymphatic system carried out by?

Cells
effector molecules
tissues
organs

2

what cells arise from lymphoid stem cells?

T lymphocytes
NK cells
B lymphocytes -- plasma cells

3

what are the two types of T cells?

Helper CD 4+
Cytotoxic CD 8+

4

what do helper CD 4 activate?

B lymphocytes
CD 8+ with IL-2 production

5

what types of lymphocytes are capable of recirculation?

T cells - 60-70% of circulating lymphocytes

6

Where are B cells produced?

bone marrow

7

what do NK cells attack?

virally infected cells
cancer/tumor cells

8

what types of cells carryout innate responses?

neutrophils
macrophages
mast cells
NK cells

9

what are the characteristics of innate responses?

fast and non specific
does not produce memory cells

10

What cells are involved in adaptive response?

B and T cells - depends on the initial recognition of antigens

11

what are the characteristics of adaptive responses?

slower and specific
produces memory cells

12

when is antibody mediate immunity (humoral immune response) important?

bacterial infections

13

what cells are involved in humoral immune responses? what are the effectors?

helper T cells
B cells
plasma cells

Immunoglobin molecules

14

When is cell mediated immunity important?

viral and fungal infections - involved in the rejection of transplanted organs and tissue grafts

15

what are the cells involved in cell mediated immunity? what are the effectors?

Cytotoxic T cells

T cells (effector)

16

what is the characteristic of diffuse, loose lymphoid tissue?

few lymphocytes present

initial immune response
found in lamina propria
intercepts antigen
no capsule

17

what is the characteristic of diffuse, dense lymphoid tissue?

many lymphocytes are present

contained in meshwork of reticular fibers
No capsule

18

what does the GC indicate?

lymphatic tissue response to antigen

19

what does a primary nodule consist of?

small lymphocytes
not ever exposed to antigen
found in newborns only

20

what does a secondary nodule consist of?

germinal cortex (GC)

21

what is the germinal cortex?

where lymphocytes undergo proliferation

22

what is a follicular dendritic cell?

Not an antigen presenting cell
help keep the antigen-antibody complex in place

23

what is the major cell found in lymphoid nodules?

B lymphocytes

24

what cells are found around the periphery of the lymphoid nodules?

T cells

25

where does the thymus originate from?

3rd pharyngeal pouch
epithelium?

26

what is important to note about the thymus?

no afferent lymphatics - just efferent

why? - because there is no filter, just production and migration through efferent

27

what type of cells make up the epithelial component of the thymus?

ERC - epithelial reticular cells

28

what are thymocytes?

immature T lymphocytes

29

what are the parenchyma of the thymus?

Cortex and medulla

30

what is in the cortex?

immature T lymphocytes = thymocytes
ERCs

31

whats in the medulla?

mature T lymphocytes
ERCs

thymic corpuscle (Hassall) - consist of rings of degenerating epithelial reticular cells

32

what type of tissue make up the thymus capsule?

dense irregular CT - throw in septa to divide tissue into lobule = trebeculae

33

what are the primary support cells in the cortex?

ERCs
they form a cytoreticulum which is held together by desmosomes (keratin)

34

what happens to the thymus after puberty?

involution - replaced with fat (accumulation)

35

What condition is the thymus gland absent?

DiGeorge Syndrome 22q11

36

where is the defect in DiGeorge's Syndrome?

Defect in the development of the 3rd & 4th branchial pouche s& arches.

37

what does the mneumonic "Catch 22" stand for?

Cardiac defects
Abnormal facies
Thymic hypoplasia
Cleft palate
Hypocalcaemia
resulting from 22q11 deletions.

38

what types of cells are found in the paracortex (inner cortex)?

T cells

39

what do lymph nodes have?

afferent lymphatic vessel - drains lymph through convex margin

40

what does the outer cortex of lymph nodes contain?

lymphatic nodules - composed of mainly B cells
few T cells, reticular cells, macrophages, antigen presenting cells

41

what do HEVs allow?

transition of lymphocytes from the blood stream to lymph tissue

found in deep cortex

42

what are the two parts of the medulla in the lymph nodes?

medullary cords
medullary sinuses

43

whats in the medullary cords?

its dense lymphoid tissue
contains B cells, plasma cells, reticular cells, macrophages

44

what do medullary sinus contain?

separates medullary cords
contains lymph, few macrophages
granulocytes maybe present

45

what makes up the stroma of lymph nodes?

reticular cells (modified fibroblasts)

46

what is the stroma of lymph nodes a framework for?

myeloid (bone marrow) and lymphoid (lymph nodes, spleen) organs

47

where does lymph tissue/organs come from?

mesoderm

48

what is the parenchyma of the spleen?

red pulp
white pulp

49

what is in the red pulp?

cords of cells (cords of Billroth)
Sinusoidal capillaries
dense network of reticular fibers - numerous erythrocytes, lymphocytes, plasma cells, macrophages and other graulocytes

50

what is in the white pulp?

thick accumulation of lymphocytes
lymphatic nodules - GC decrease with age

51

what is PALS?

T lymphocytes surround the central artery
"peri arteriolar lymphatic sheath"

52

what surrounds PALS?

B cells - sheathed artery

53

what is the marginal zone?

the rim of lymphocytes (T cells and B cells) along with APCs and macrophages

54

where do lymphocytes first come in contact with antigens?

marginal zone

55

in the red pulp, the central a. gives ride to what?

penicillar arteries which ultimately become sinusoidal capillaries

56

what is closed circulation?

sinusoidal capillaries may continue into venues to pulp veins

57

what is open circulation?

sinusoidal capillaries can open into the cords, drain blood cells and eventually the pulp veins are formed

58

what are splenic sinusoids lined by?

elongated endothelial cells (Littoral Cells) - supported by an incomplete basal lamina of reticular fibers

59

what is the function of macrophages in circulation?

to remove damaged or effete erythrocytes from circulation

60

what secondary lymphoid organ is GALT?

"gut associated lymphoid tissue"
Tonsils

61

what is the function of the tonsils?

process antigens that enter the body through oral cavity and nasal passage

62

what are lymphatic tissue lined by epithelium?

tonsils

63

how many palatine tonsils do we have?

2

64

what are crypts and what do they do?

invagination of epithelium
contain desquamated epithelial cells, live and dead lymphocytes and bacteria

65

what is found in the region where crypts are found?

mainly secondary nodules (with GC)

66

what is the purpose of the posterior separation from the superior constrictors by a thick capsule?

prevents the spread of infection

67

what is pharyngeal tonsils lined with?

pseudostratified columnar epithelium = respiratory epithelium

68

what do you call inflammed pharyngeal tonsils?

adenoids

69

what is Waldeyer's Ring?

1 pharyngeal tonsil
2 palatine tonsils
1 lingual tonsil

70

what do thymic corpuscles have?

keratin filaments which can be keratinized and calcify - which is why in elderly people you can see calcified spots in thymus in the superior mediastinum

71

if you see a central artery, what organ are we looking at?

spleen!