Pod Ream Histology Of Lymphoid Organs

Front 1

Areolar connective tissue covered by mesothelium

Back 1

Serous Membranes

Front 2

What are the first, second and third lines of defense against pathogens?

Back 2

1st Skin and mucous membranes
2nd Internal Defenses (internal antimicrobial proteins, phagocytes, NK cells, inflammation and fever)
3rd Internal defenses (Adaptive immune system)

Front 3

The end result of this activation cascade is massive amplification of the response and activation of the cell-killing membrane attack complex. Over 20 proteins and protein fragments make up the system, including serum proteins, serosal proteins, and cell membrane receptors. These proteins are synthesized mainly in the liver, and they account for about 5% of the globulin fraction of blood serum.

Back 3

Complement

Front 4

T cells, B cells and APC's are all part of the:

Back 4

Adaptive Immune System

Front 5

How do T cells, B cells and APC's communicate?

Back 5

Communicate via cytokines

Front 6

What causes T cells, B cells and APC's to release cytokines?

Back 6

Encounter an antigen

Front 7

Explain the five properties of the adaptive immune system
Specificity
Diversity
Memory
Self-limitation
Tolerance

Back 7

Specificity: lymphocytes recognize specific domains of an antigen
Diversity: modify antigen receptors
Memory: clonal expansion by mitosis, and generation of reserve memory cells
Self-limitation: when antigen is neutralized the response disappears
Tolerance: Tolerant to self antigens, acheived via selection mechanism

Front 8

Exist as diffuse deposits or as more sharply defined nodules

Back 8

Lymphoid Tissues

Front 9

Lymphoid Organs
Central/ Primary:
Peripheral/Secondary:

Back 9

Central/ Primary: Bone marrow, Thymus
Peripheral/Secondary: Lymph node, spleen, tonsils, Peyer's patches

Front 10

Where is lymphocyte production antigen dependent?

Back 10

Peripheral or secondary lymphoid organs

Front 11

Specific location of T cell development in Peripheral or secondary lymphoid organs?

Back 11

Thymic-dependent zones

Front 12

Specific location of B cell development in Peripheral or secondary lymphoid organs?

Back 12

Bursa-dependent zones

Front 13

The recognition molecules of B cells, carried on the B cell surface are:

Back 13

Membrane bound IgD
(Known as B-cell receptors or SIG's)

Front 14

How long does it take for recognition of a pathogen to result in a powerful, tailored immune response via lymphocyte selection and differentitation?

Back 14

1-2 weeks

Front 15

How is a B cell activated?

Back 15

SIG reacts with its epitope

Front 16

Only recognize epitopes presented to them:

Back 16

T cells

Front 17

Respond only to protein antigens, and perform fx only at short distances:

Back 17

T cells

Front 18

What are the four subtypes of T cells?

Back 18

T Helper cells 1 & 2
Cytotoxic T cells
Suppressor T cells
T memory cells

Front 19

What do TH1, T Helper cells, type 1 do?

Back 19

Fight bacterial or viral infection

Front 20

What do TH2, T Helper cells, type 2 do?

Back 20

Fight parasitic IgE, or Mucosal infection IgA

Front 21

What is NEVER found in peripheral blood?

Back 21

Plasma cells

Front 22

Null Cell Population: do not have TCR or cell surface Ig's
What two cells account for a portion of the null cell population of lymphocytes?

Back 22

NK cells
Stem cells

Front 23

Do NK cells act nonspecifically?
What do NK cells contain?
Where are NK cells found?

Back 23

yes
Azurophillic Granules
In peripheral blood

Front 24

What two cell types kill virally and tumor-altered cells?

Back 24

CTL's and NK cells

Front 25

What type of cells can recognize Fc region of antibodies and preferentially kill cells coated with antibodies? What is this process called?

Back 25

NK cells
Antibody-dependent cell-mediated cytotoxicity

Front 26

What cell type has the following receptors?
IL-12
Lipopolysaccaride (bac wall)
IFN-α
IFN-β

Back 26

NK cells

Front 27

Do dendritic cells express MCH I or MHC II on their plasma membrane?

Back 27

Both

Front 28

Most APC's are derived from monocytes and therefore belong to the :

Back 28

Mononuclear Phagocytic system

Front 29

All of the following are:
Which of the following are not monocyte derived?
Macrophages
dendritic cells
B cells
Epi Reticular cells of thymus

Back 29

APC's

B cells and Epi Reticular cells of thymus

Front 30

Phagocytose, catabolize, and process antigens, attach their epitopes to MCH II molecules and present complex to T cells

Back 30

APC's

Front 31

Found in the paracortex of the lymph node and marginal zone in the splenic pulp

Back 31

dendritic cells

Front 32

Most important/effiecient APC's

Back 32

dendritic and Langerhan cells

Front 33

Star shaped morphology

Back 33

dendritic cells

Front 34

What is a valid concern of follicular dendritic cells? Where are they found?
Are the formed in the bone marrow?

Back 34

Found in lymphoid nodules, binds antigen for a long period of time, exposing it to antigen longer, but also boosts antigen presentation as peptide fragments.
NOT from bone marrow precursor

Front 35

What is the main stromal element of lymphoid tissue?

Back 35

Reticular fibers and cells

Front 36

A specialized connective tissue?

Back 36

Lymphoid tissue

Front 37

Complex cellular framework in lymphoid tissues.
Morphologically and fx similar to fibroblasts.
Synthesize fibrous reticulum

Back 37

Reticular cells in lymphoid tissue

Front 38

Type III collagen fibers are:

Back 38

Reticular Fibers

Front 39

Reticular fibers are argyophillic and are therefore:

Back 39

easily seen on silver stained sections

Front 40

In lymphoid tissue; consists of a system of type III collagen fibers w/ a lot of bound proteoglycans

Back 40

Fibrous reticulum

Front 41

a special class of glycoproteins that are heavily glycosylated. They consist of a core protein with one or more covalently attached glycosaminoglycan (GAG) chain(s). These glycosaminoglycan chains are long, linear carbohydrate polymers that are negatively charged under physiological conditions, due to the occurrence of sulfate and uronic acid groups.

Back 41

proteoglycans

Front 42

NALT, GALT, VALT, and SALT are all examples of:

Back 42

Mucosae-associated lymphoid tissue, composed of NONENCAPSULATED lymphocytes and lymphoid nodules

Front 43

Primary functional units of all lymphoid tissue except for the thymus?

Back 43

Lymphoid Nodules

Front 44

Are lymphoid nodules encapsulated?

Back 44

No

Front 45

Lymphoid Nodules, what are primary and secondary nodules?

Back 45

Primary Nodules: homogenous mass of small lymphocytes
Secondary Nodules: contains a germinal center

Front 46

The aspect of immunity that is mediated by secreted antibodies (as opposed to cell-mediated immunity which involves T lymphocytes), produced in the cells of the B lymphocyte lineage (B cell). Secreted antibodies bind to antigens on the surfaces of invading microbes (such as viruses or bacteria), which flags them for destruction. Is called as such, because it involves substances found in the humours, or body fluids.

Back 46

Humoral Immunity

Front 47

The dense rim of small B memory lymphocytes that surround a germinal center:

Back 47

Follicular mantle or corona

Front 48

What is located in the germinal center (secondary nodule)

Back 48

B lymphoblasts

Front 49

Germinal centers are sites of blastic transformations. What does this mean? What prompts this? What assists in the blastic transformatons?

Back 49

This means B Lymphocytes become B lymphoblasts due to antigenic stimulation. This is assisted by T helper cells type 2

Front 50

Are mature plasma cells found in the germinal center?

Back 50

Typically not because they migrate out.

Front 51

In the lymphoid nodule, how is the lymphocyte cap (dome) oriented? What is a lymphocyte cap?

Back 51

Toward the source of antigen
A lymphocyte cap is a crescent shape of small lymphocytes, B memory or simply B cels

Front 52

Give three locations of aggregated lymphoid nodules:

Back 52

Peyer's Patches, tonsils and appendix

Front 53

secondary lymphoid organs, they are aggregations of lymphoid tissue that are usually found in the lowest portion of the small intestine (ileum) in humans; as such, they differentiate the ileum from the duodenum and jejunum in that the number of them increase further down the intestine

Back 53

Peyer's Patches

Front 54

Are lymphoid nodules encapsulated?

Back 54

no

Front 55

Where are Paneth cells found?

Back 55

In the crypts of Leiberkhun (Sml In)

Front 56

Paneth cells have bright red granules. What three products are in the granules?

Back 56

TNFα, Lysozyme (cleaves bonds and kills bacteria) and defensins (antimicrobial)

Front 57

Squamous-like cells in the ilium adjacent to lymphoid nodules:

Back 57

M cells

Front 58

Action of M cells

Back 58

capture antigens and package them into clathrin-coated vesicles, and essentially pass the buck to the APC's in the lamina propria, to initiate an immune response

Front 59

Peyer's Patches only have one type of lymphatic vessel

Back 59

No afferent but do have efferent lymph drainage. Drain via HEV's

Front 60

Are specialized post-capillary venous swellings characterized by simple cuboidal cells as opposed to simple squamous cells found in regular venules. This allows for re-entry of lymphocytes into the bloodstream through

Back 60

High Endothelial venules (HEV"s)

Front 61

Secretory IgA in GALT is bound to the glycocalyx. How does this IgA differ from typical IgA?

Back 61

It is complexed to a protein secretd by surface absorptive cells and then transported to the lumen by transcytosis

Front 62

Basic Idea of large Lymphatic vessels:

Back 62

Have valves, have lymph nodes along their routes to filter lymph, converge and become thoracic duct and right lymphatic duct, and empty into left subclavian

Front 63

How does lymph move through lymphatic vessels?

Back 63

Valves prevent backflow, and forward movement is due to compression by adjacent skeletal muscle (even during sleep) and contraction of smooth muscle.

Front 64

What is the purpose of lymph nodes?

Back 64

The location of immune reactions to lymph borne antigens, produce B cells and house T cells.

Front 65

Lymph Nodes have a capsule of?

Back 65

Dense irregular cx tissue, Type 1 (duh) and 3D reticular cx tissue

Front 66

What is the flow of lymph in lymph nodes?

Back 66

1. Afferent lymphatic vessel
2. Subcapsular sinus
3. Trabecular sinus
4. Medullary sinus
5. Efferent lymphatic vessel

Front 67

Do most of the nodules (located in the cortex) of the lymph node have germinal centers?

Back 67

yes

Front 68

What part of the lymph node represents the bursa-dependent zone?

Back 68

The cortex

T cells occupy the parafollicular regions

Front 69

Why do lymph nodes make such good breeding grounds for metastatic cancer cells?

Back 69

Because they are form a chain, and move slowly.

Front 70

Do lymphatic sinuses only permeate some parts of the lymph node? How are lymph sinuses lined?

Back 70

No, they branch and anastomose and permeate all compartments of the lymph nodes
Lined by discontinuous endothelial cells

Front 71

What is the purpose of the reticular fibers and cells that span the lumen of the lymph sinuses?

Back 71

They slow down lymph flow to facilitate recognition of foreign materials and subsequent phagocytosis

Front 72

What are the predominant cell types in the medulla of the lymph nodes?

Back 72

macrophages ad plasma cells

Front 73

Is the entire medulla surrounded by the cortex?

Back 73

no, not at the hilus

Front 74

How is the medulla set up? Are nodules present?

Back 74

In cords, nodules are not present

Front 75

Where do the cords of the medulla of lymph nodes converge?

Back 75

At the hilus

Front 76

Where is phagocytosis more evident, in the cortex or medulla?

Back 76

In the medulla

Front 77

Where do plasma cells develop into mature Ig secreting plasma cells in Lymph nodes?

Back 77

In the medullary cords.
This is key because here they can secrete IgM and IgG w/o leaving the lymph nodes

Front 78

Main types of lymphocytes found in the paracortex of the lymph nodes?

Back 78

CD4 helper T cells

Front 79

How is the paracortex of the lymph nodes set up?

Back 79

As diffuse lymphoid tissue lacking in nodules

Front 80

Development of the paracortex is dependent on what?

Back 80

T cells from the thymus

Front 81

What part of the lymph nodes is the thymus dependent zone?

Back 81

The paracortex

Front 82

What can cause the paracortex area to expand?

Back 82

A T-cell dominated immunologic response.

Front 83

How do lymphocytes entering the lymph nodes from the blood, get to the paracortex and cortex??
How do they leave?

Back 83

Via HEV's
They leave via efferent lymphatic vessels

Front 84

Explain the blood flow in lymph nodes:

Back 84

arterioles -> cap bed in cortex -> post cap venules -> veins

Front 85

Where do postcapillary venules form in the lymph node?

Back 85

In the paracortex

Front 86

what is the MAIN route of entry into the lymph nodes for lymphocytes?

Back 86

Blood supply

Front 87

What are HEV's?

Back 87

High Endothelial Venules, simply put, they are postcapillary venules with tall cuboidal epi. They have lymphocyte homing receptors, causing the lymphocytes in blood to pass thruough to the lymph sinuses

Front 88

Lymphocytes have selectins and integrins on their surface. What is their role?

Back 88

Selectins help the lymphocyte to recognize the HEV and allow it to roll. Integrins bind to the HEV, so it stops rolling, and they diapedese to lymph node parenchyma

Front 89

Why is lymphocyte recirculation so important?

Back 89

It increases the likelihood of a lymphocyte encountering the antigens to which it is programmed to react.

Front 90

How do macrophages filter lymph?

Back 90

Some project processes into the sinuses and others are attached to the reticular cells in the sinuses.

Front 91

Is the spleen a vital organ?

Back 91

no, even though it is the second largest lymphoid organ in the body

Front 92

What are the two purposes of the spleen?

Back 92

1. Filter of unneeded and damaged blood cells
2. Immunological reaction site for blood borne antigens resulting in T and B cell proliferation

Front 93

The spleen is like most compact organs with a hilus, capsule and trabeculae but it does not have:

Back 93

cortex and medulla
Instead it has red and white pulp compartments.

Front 94

White pulp compartments in the spleen are areas of dense....

Back 94

lymphoid tissue (t and b cells)
White compartment is the immune component of the spleen.

Front 95

Where is red pulp in the spleen?

Back 95

Reddish material around the white pulp.
Red pulp functions to remove aged and damaged RBC's and storage site for RBC's and platelets. (blood is contained in blood vessels)

Front 96

Do splenic cords and venous sinuses have HEV's?

Back 96

no

Front 97

Are nodules in the spleen located in the red or white pulp?
What type of pulp surrounds the central arteries?

Back 97

White
White

Front 98

What are the splenic cords of bilroth?

Back 98

(also known as red pulp cords) are found in the red pulp of the spleen between the sinusoids, consisting of fibrils and connective tissue cells with a large population of monocytes, plasma cells and macrophages. It is a cord in the vascular space, ie blood is not in a blood vessel.

Front 99

What are the PALS?
Non-nodular areas of the PALS have a lot of:
The nodular areas are:

Back 99

Densely packed lymphoid tissue around the central arteries

T-lymphocytes, so this area is the thymus dependent area

Bursa-dependent zone, B cell's proliferate here and react w/ antigens in blood.

Front 100

What does the marginal zone in the spleen separate? What cell types are found here?

Back 100

Red and white pulp

Plasma cells, T and B lymphocytes, macrophagesand dendrictic cells

Front 101

What are the three funcitons of the marginal zone in the spleen?

Back 101

1. First location in which blood-borne antigens encounter immunologically competent cells.
2. The lymphocytes leave the marginal zone to filter through the white pulp and immune response occurs if dendritic cells recognize their epitope-MHC complex
3. Some plasma cells remain in marginal zone to manufacture and release antibodies (IgG mainly)...but this typically occur in the bone marrow.

Front 102

The thymus is a primary lymphoid organ. It has nothing to do with:

Back 102

B cells

Front 103

Where is the thymus located? How come Ream has never seen one?

Back 103

In the mediastinum
It involutes, so it is very hard to see in adults (cadavers)

Front 104

Where are Hassals corpuscles located?

Back 104

In the medulla of the thymus

Front 105

What is the arrangement of the thymus?
What is there NONE of?

Back 105

It is bilobed, has a capsule and trabeculae, has a cortex (darker staining) and medulla (lighter staining)
NO reticular connective tissue

Front 106

What type of blood vessels are in the cortex of the thymus? What type of cells? Thick or thin basal lamina?

Back 106

Continuous capillaries
Endothelial cells w/ T jx
Thick basal lamina
Loop through the cortex

Front 107

The thymus does not have a fibrous reticulum. Instead it has a:

Back 107

cellular reticulum formed by epithelial reticular cells

Front 108

What are reticulocytes?

Back 108

RBC precursors..duh...don't confuse w/ reticular cells

Front 109

What are epithelial reticular cells

Back 109

Loose intercommunicating network of cells

Front 110

Flattened or stelate w/ many tapering cytoplasmic processes, VERY eosinophillic

Back 110

ERC's (there are six types)

Front 111

Types 1-3 ERC's are located where? Whate are they from?
Typse 4-6 ERC's are located where? What are they from?

Back 111

In the cortex of the thymus, ectoderm

In the medulla of the thymus, endoderm

Front 112

What is the importance of type I ERC's in the thymus? How are they connected? Shape?

Back 112

They line up and create a barrier around looping blood vessels in the cortex, are connected via T jxs, and are where the T cells develop. They are flat.

Front 113

Type II and III ERC's are important in the cortex because they not only have the typical Class I MHC, but also have:
How are II and III shaped?

Back 113

Class II MHC to "educate" the T cells. They are stellate in shape, due to processes.

Front 114

If developing T cells cannot recognize self MHC, what happens to them?

Back 114

They are killed

Front 115

Type VI ERC's form _____________ in the medulla.

Back 115

Hassels Corpuscles

Front 116

Is the thymus a endocrine organ?

Back 116

Yes, because it secretes 4 growth factors, though it mostly acts in the paracrine mode

Front 117

Describe the epithelial reticular cells

Back 117

They are true epithelial cells, ie they have keratin IF and have desmosomes (MA). There are six types.

Front 118

What are four general things located in the cortex of the thymus?

Back 118

Type I to III ERC's
Macrophages
Looping Capillaries
T cells

Front 119

The cortex is the location of the blood thymus barrier. This includes:

Back 119

T jx btwn endothelial cells
Thick basal lamina
Perivascular CT w/ pericytes and macrophages
T Jx btwn type I ERC's

Front 120

T lymphocytes and prothymocytes develop from

Back 120

Lymphoid progenitor cells from bone marrow

Front 121

What is located in the superficial part of the cortex, near the capsule?

Back 121

Lymphoblasts

Front 122

Cells that develop in the _________ acquire the characteristics that define their role in botht he cell mediated immune response and the humoral immune response.

Back 122

Thymus

Front 123

As T cells develop, what direction in the thymus do they move? What type of selection do they undergo? What type of receptor do they acquire? Where do they exit?

Back 123

T cells undergo pos and neg selection (98% are killed) they acquire TCR's, move towards the corticomedullary jx and exit via post-cap venules

Front 124

What happens if they react against self (no self tolerance) or if they don't react against non self?

Back 124

They apoptose and are phagocytosed by resident macrophages

Front 125

What is the importance of the blood-thymus barrier?

Back 125

To sheild T lymphocytes from antigens Some components are T Jx of endothelial cells, perivascular macrophages, type I ERC's wrapped around cappillaries and connected via VERY T Jx

Front 126

After T cell develop, they migrate to thymic dependent areas. What are they? (3)

Back 126

paracortical region of lymph nodes
Diffuse regions of Peyer's patches
Periarterial lymphoid sheaths of spleen (PALS)

Front 127

CD8 lymphocytes become:
CD4 lymphocytes become:

Back 127

Killer T cells
Helper T cells

Front 128

What is the immunological significance of the medulla of the thymus?
Can you see reticular cells in the medulla?

Back 128

None known

yes, quite easily.

Front 129

Lyphocytes are less dense in the medulla of the thymus. Do they come from the cortex of the thymus?

Back 129

NO, T cells in medulla have to travel to thymic dependent areas and then may travel back to the medulla of the thymus via typical circulation.

Front 130

The Hassal's corpuscles come from ERC's Type ?
What do they become filled with? Why?

Back 130

6
Keratohyalin granules, not sure why

Front 131

At what age is the thymus fully developed? When is it largest?

Back 131

Fully developed at birth
Largest at puberty

Front 132

What does it mean that the thymus undergoes involution?

Back 132

It progressively atrophy's but is still present

Front 133

What are some characterisitics of the adult thymus?

Back 133

Decrease in weight
Increase in fat cells
Decrease in T cells
More and larger Hassal's corpuscles

Front 134

Route taken by antigen to which it responds: Tonsils

Back 134

Tissue fluid

Front 135

Route taken by antigen to which it responds: Lymph Nodes

Back 135

Lymph

Front 136

Route taken by antigen to which it responds: Spleen

Back 136

Blood

Front 137

Route taken by antigen to which it responds: Thymus

Back 137

Thymus cortex is SHEILDED and therefore NONRESPONSIVE, no antigens get here!!!

Front 138

Erythrophagocytosis in the spleen occurs where?

Back 138

Cord of Billroth

Front 139

What cell in the splenic white pulp manufactures and releases interleukins?

Back 139

T helper cells

Front 140

What cells produce thymosin?

Back 140

ERC's