Lymphoid Tissue

Question 1

Why are the respiratory and genitourinary tract prone to invasions by pathogens?

Answer 1

lumen is exposed to the external environment. (remember mucosa surfaces are vulnerable to infections)

Question 2

3 types of lymphocytes are what?

Answer 2

1) Nk cells
2) T cells
3) B cells

Question 3

Which lymphoid tissue is not surrounded by a capsule and why does it look like it is?

Answer 3

Diffuse lymphoid Tissue

Because its a lot of lymphocytes clustered together possibly forming nodules in the lamina propia.

Question 4

Peyers patches are examples of what kind of lymphoid tissue?

Answer 4

Diffuse lymphoid tissue or MALT (mucosa associated lymphatic tissue)

Question 5

The initial site of immune response is what kind of Tissue?

Answer 5

Diffuse lymphoid Tissue

Question 6

Name the capsulated lymphoid organs:

Answer 6

Spleen
Thymus
Lymph node

(remember tonsils are partially encapsulated)

Question 7

What makes up the framework in both lymphoid

tissue and lymphoid organs except the thymus?

Answer 7

Reticular fibers secreted by reticular cells

Question 8

In the thymus what forms the framework?

Answer 8

epithelial reticular cells

Question 9

What is Lymphocyte recirculation?

Answer 9

The continuous movement of T and B cells from one location to another they are never anchored in the lymphoid tissue or organ

Question 10

Why do people present with swollen lymph nodes?

Answer 10

immune system has been activated to fight an invader so there is an increase of lymphocytes within the node

Question 11

Where do B lymphocyte become immunocompetent?

Answer 11

Red Bone Marrow

Question 12

Where do CFU-L cells from the bone marrow go to produce immunocompetent T cells

Answer 12

Thymus

Question 13

Why does the cortex stain darkly as compared to the medulla?

Answer 13

The cortex has more lymphocytes

Question 14

Why is the medulla Stain lighter?

Answer 14

Because there is less lymphocytes there ( REMEMBER 95% of lymphocytes die by apoptosis before they get to the medulla)

Question 15

The cytoplasm of the childs thymus contain what?

Answer 15

Tonofilaments/Keratin filaments

Question 16

What is the embryological origin of the ERCs

Answer 16

Endoderm

Question 17

What is the embryological origin of the T lymphocytes

Answer 17

Mesoderm

Question 18

Thymosin, Thymulin and Thymopoetin are secreted by what?

Answer 18

Epithelial Reticular Cells

Question 19

The blood thymus barrier protects the immature thymocytes from antigens. What creates the blood thymus barrier?

Answer 19

type 1 ERCs

Question 20

Fibroblasts in the thymus form what?

Answer 20

Capsule and trabeculae

Question 21

All APCs contain what kind of molecules on them?

Answer 21

Class II MHC

Question 22

In the medulla what cells are involved in the destruction of the thymocytes that recognize self?

Answer 22

Dendritic cells

Question 23

a rounded globular mass of cells within the medulla is called what?

Answer 23

hassals corpuscle

Question 24

Hassals corpuscles are made from what?

Answer 24

ERCs

Question 25

The failure the thymus to develop properly is called what? What causes this to occur?

Answer 25

Di Georges syndrome faulty development in the 3rd and 4th pharyngeal arches

Question 26

Germinal centers are found in which lymphoid nodules?

Answer 26

secondary ( remember it stains lighter because the B cells are proliferating and switch their class of antibodies)

Question 27

What cell would you find within the germinal center?

Answer 27

Follicular dendritic cell (FDC)

Question 28

What is the function of the Follicular Dendritic Cell?

Answer 28

they can trap antigens for months or years and They form a network to attract and organize lymphoid cells

Question 29

The embryological origin of FDCs are:

Answer 29

Mesenchymal

Question 30

Why are the FDCs different when it comes to their comparison with APCs?

Answer 30

They dont have MHC II molecules.

Question 31

The accumulation of lymphatic tissue within the ileum is called what?

Answer 31

peyers patch

Question 32

The primary function of M cells?

Answer 32

they transfer antigens from the lumen by phagocytocis or pinocytosis without processing them to the lymphocytes and macrophages lying deep within. * THEY ARE NOT APCs

Question 33

How do foreign substances reach the palantine tonssils?

Answer 33

Crypts

Question 34

Which tonsil will you not find crypts and lies beneath pseudostratified ciliated columnar epithelium?

Answer 34

pharyngeal tonsils

Question 35

A single crypt that is lined by non-karitinized stratified squamous epithelium can be found where?

Answer 35

Lingual tonsil

Question 36

In the lymph node where do must lymphocytes enter through?

Answer 36

HEVs

Question 37

The endothelial cells lining the venules are what?

Answer 37

cuboidal

Question 38

Homing is referred to as what?

Answer 38

the movement of T and B lymphocytes through the HEVs

Question 39

Where are B cells concentrated within the spleen or lymphnode?

Answer 39

Outer cortex

Question 40

Where are T cells concentrated?

Answer 40

paracortex

Question 41

The subscapular sinus is composed of what?

Answer 41

Loose network of reticulum cells and fibers

Question 42

The main cell type within the medullary cord is what?

Answer 42

Plasma Cells and B cells

Question 43

Sinusoids and Splenic cords ( bilroth) are found where in the spleen?

Answer 43

Red pulp

Question 44

The periarterioal lymphoid sheath is found where?

Answer 44

Within the white pulp

Question 45

White pulp functions as what?

Answer 45

Location where B cell clones are found along with T-cells that come from the PALS

Question 46

What is the role of the marginal zone?

Answer 46

To trap the antigen from circulation to present it to the lymphocytes of the spleen

Question 47

In the spleen where do the antigens enter?

Answer 47

Through the blood ( remember antigens enter through the lymph in the lymph node)

Question 48

Describe the Path of the pathogen as it enters the spleen.

Answer 48

Antigen enters through the blood, and goes toward white pulp through trabeculated arteries and marginal sinus>>>>>> APCs detect them by the PALS>>> T cells interact with B cells>>> B cells proliferate and differentiate into plasma>>> plasma secretes Igs to the blood circulation

Question 49

Describe the path of open circulation.

Answer 49

Blood from white pulp go to >>>penicillar arteries>>>sheathed capillaries>>> percolate in the red pulp cords>>> red pulp sinusoids>> veins

Question 50

Stave cells line what?

Answer 50

Splenic venous sinus

Question 51

How are the damaged RBCs removed when someone does not have a spleen?

Answer 51

macrophages in the liver and bone marrow

Question 52

What lymph organs contain efferent lymph vessels?

Answer 52

Thymus, Spleen, Tonsils