Morphology and function of lymphoid organs (ketchum) Flashcards

1
Q

lymphoid system functions

A

monitor neutralize and destroy harmful agents

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2
Q

Thymic epithelial cell are what type of cells (functional or stromal)

A

functional and stromal

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3
Q

Reticular cells produce fibers with what type collagen

A

type III

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4
Q

Functional cells of lympoid system

A

lymphocytes, macrophages, APCs and TECs thymic epithelial cells

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5
Q

Does everyone have cancer

A

yes at some point but the immune system responds and kills cells before they can proliferate

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6
Q

2 primary cells in immune response

A

B lymphocytes- specific ab producing

T lymphocytes- T helper, cytotoxic cells, and regulatory

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7
Q

What type of lymphocytes are with humoral immunity and cellular immunity

A

B- humoral

T- cellular

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8
Q

maturation of lymphocytes occur in

A

bone marrow and thymus

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9
Q

Once lymphocytes mature where do they go

A

peripheral tissues or spleen or lymph node

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10
Q

what is the direct effect when the primary immune response is stimulated

A

cell proliferates (immunoblasts) to make clones to bind and kill

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11
Q

quiescent B cells

A

memory cells ready for secondary immune response or re exposure of Ag- rapid response

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12
Q

Instead of producing ab what to T cells do

A

produce antigen recognizing receptor

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13
Q

What is the actual name for a b lymphocyte producing ab

A

plasma cell. eccentric nucleus, clockface nucleus because of chromatin clumping.
perinuclear clear zone- golgi because exporting lots lots of protein.
very basophilic because ribosomes

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14
Q

how is our immune system so great if we only have 20 cells specific to each Ag

A

upon stimulation, cells proliferate

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15
Q

how do we organize the lymphoid system

A

collections in organs or tissues. un encapsulated and encapsulated

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16
Q

what is a Lymph nodule, is it encapsulated or not.

A

large collection of lymphocytes- un-encapsulated

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17
Q

Which are more active primary or secondary lymphocytes and what are their appearances

A

secondary are more active, have a pale center where lymphocytes are proliferating and differentiating

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18
Q

diffuse un encapsulated collections of lymphocytes indicates what

A

activity, infection in that area

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19
Q

Hyaline cartilage with cilia and globule cells is indicative of what

A

trachea

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20
Q

name of lymphocyte collection in the intestine

A

peyers patches- dark staining in mucosa of gut.

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21
Q

GALT

A

gut associated lymphoid tissue

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22
Q

Malt

A

mucus associate lymphoid tissue

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23
Q

Are tonsils encapsulated

A

not entirely, partially

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24
Q

Characteristics of palantine tonsil

A

large paired collections nodules
stratified squamous non keratinized epithelium
epithelial crypts to increase SA

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25
Q

characteristics of pharyngeal tonsil

A

pseudostratified columnar epithelium with cilia and globular because like respiratory tract
single crypts
ECM- collagen type III fibers

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26
Q

characteristics of lingual tonsils

A

no crypts. smaller more numerous nodules. huge salivary glands.
very similar to palantine minue crypts

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27
Q

What is the name for encapsulate lymph

A

lymph nodes

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28
Q

Where to the afferent lymphatics enter node. where do efferents exit

A

thru capsule enter

exit via hilum

29
Q

paraenchyma divided into ?

A

cortex and medulla

30
Q

Cortex components

A

sinues, nodules
diffuse lymphoid tissue
connective tissue trabeculae

31
Q

Medulla components

A

medullary cords, sinuses and trabeculae

32
Q

What is the architecture of the cortex

A

irregular sinuses. “subcapsular sinus” then move into cortical or paratrabecular sinuses
bathes all the lymphocytes and if lymphocyte recognizes anything in fluid, reaction

33
Q

Where are B lymphocytes typically found in cortex? T lymphocytes?

A

B- nodular areas

T- non-nodular

34
Q

Where to macrophages present Ag to lymphocytes

A

in germinal centers

35
Q

Majority of cells in medullary cords

A

B cells and plasma

36
Q

Trabeculae in medulla characterized by

A

anucelate, white appearance, high in collagen III and some I

37
Q

Paracortex

A

not nodular. mostly T lymphocytes. inner to cortex layer.

38
Q

When an Ag comes into lymph node what cells will they encounter first

A

B cells in node and then T cells in paracortex

39
Q

blood vessels in lymph nodes used for?

A

trafficking. T cells enter and leave circulating in periphery but will return through specialized capillaries HEVs

40
Q

HEVs

A

high endothelial venule- looser tight junctions to allow cells to diapedis in and out. to enter and exit blood.

41
Q

What does the epithelial look like around HEVs

A

cuboidal, not like normal squamous

42
Q

Functions of spleen

A

filters blood
salvages Fe from old RBCs
sire of generation of abs by plasma cells
reservoir of RBCs
site of erythropoiesis in fetus during 3rd/4th- 7th month

43
Q

Structure of spleen

A

fibro-muscular capsule.
does not have afferent lymphatic. only efferent
arteries and veins (splenic vein formed by trabeculae veins)

44
Q

Paraenchyma composition of spleen

A

no cortex or medulla but has red and white pulp
red pulp-RBCs
white pulp- WBCs

45
Q

Structure of white pulp

A

vessels are surrounded by T lymphocytes. Periarterial lympoid sheath PALS

46
Q

Structure of red pulp

A

blood vessels. filtration is happening. turnover of RBCs- hemocidrin- Fe being recovered by macrophages
plasma cells to produce ab

47
Q

Describe splenic circulation

A

Open: capillaries dump right into red pulp, these RBCs have to get back into sinusoids so this is where we recycle RBCs that lyse as they try to migrate through capillaries
Closed: channel comes in and exits (artery arteriole capillary vein)

48
Q

basic Artery spleen

A

splenic artery- trabecular arteries- penicillar arteries (pulp) branch into central arteries in white pulp that either go directly into sinus (closed) or into red pulp (open)

49
Q

Is the thymus nodular

A

no, cortex and continuous medulla

50
Q

What lymph cells are found in thymus

A

thymocytes to mature into T lymphocytes

51
Q

What is the thymic stroma made of

A

thymic epithelial cells- they do not make fibers

more functional because secrete cytokines and present antigens

52
Q

Vascular of thymus

A

enter cortico-medullary junction to where it branches into either cortex or medulla

53
Q

What is the blood thymus barrier

A

sheathed by macrophages and thymic epithelial cells. They form nests for maturing thymocytes
teach T lymphocytes what to recognize. self vs nonself

54
Q

Each capillary of blood thymus barrier is surround by what

A

endothelial cell lining it, a macrophage associated with it and a thymic epithelial cell to extend a process to wrap around it

55
Q

Does thymus have afferent/efferent lymphatics

A

only efferent

56
Q

Hassall’s corpuscles

A

no known function but how we characterize the medulla of thymus.
the corpuscles produce TSLP Thymic lymphopoietin
accumulate with time

57
Q

TSLP

A

helps T cells mature. specifically T regulatory cell

58
Q

Characterization of older thymus

A

adipocytes-clear areas
dense lymphocyte populations
a lot of stromal areas that have built up over time
“a trophic” still functional but not growing

59
Q

Thymus involution

A

decreased lymphocytes and function over time, weaker immune system with age

60
Q

how do T lymphocytes make it to thymus for maturation

A

CD44 when leave bone marrow

interacts with cytokines CCL21 and CCL25 to stick to thymus

61
Q

Maturation of T lymphocytes in thymus

A

1) CD4, CD8 CD25 negative, CD44+ Double neg (DN1)
2) develop CD25 so now called (DN2)
3) lose CD44 = (DN3)
4) lose CD 25 = (DN4)
5) develop CD4 and CD8 (DP) double+
6) lose either CD4 or CD8 to become SP single+

62
Q

Where in the thymus are DN4 lymphocytes found

A

cortex

63
Q

Where in the thymus are DP lymphocytes found

A

cortico-medullary junction

64
Q

Where in the thymus are the SP lymphocytes found

A

medulla to exit into circulation

65
Q

What part of immune education occurs in the cortex of thymus

A

positive selection. immature T lymphocyte comes in contact with thymic epithelial cells. want to keep cells that recognize TEC, ability to communicate with self

66
Q

What part of immune education occurs in medulla of thymus and at what stage are the lymphocytes?

A

DP lymphocytes. Negative selection, get rid of cells that recognize APCs(macrophages and dendritic cells) these APCs are presenting SELF antigens.

67
Q

Describe B cell T-independence and T-cell dependence

A

T cell independence: B cells can be activated directly by bacterial toxins
T cell dependence: majority, helper T cells stimulate B cell proliferation and activation by secreting IL 4, 5 and 13

68
Q

Mode of HIV on T cells

A

infect and inactivate helper T cells- enter by binding CD4 at cell surface.