Histology of the Immune System

Question 1

What are the two main functions of the immune system?

Answer 1

Make cells and complements to keep bad things out, and recognize non-self from self.

Question 2

What are the primary lymphoid organs?

Answer 2

bone marrow (both T and B made here), and thymus (only T cells mature here)

Question 3

What are secondary lymphoid organs?

Answer 3

spleen - blood filter, and lymph node - lymph filter

Question 4

What part of the antigen to antibodies recognize?

Answer 4

The epitope, which is specific domain of the antigen

Question 5

What is difference between humoral and cellular immunity?

Answer 5

when antibody removes the antigen it is humoral, when cell removes and presents it is cellular.

Question 6

What can you find in lymphatic nodules?

Answer 6

Lots of B cells congregated trying to fight off infection in the germinal centers of these nodules; under high mag you should see plasma cells in germinal center (clock looking)

Question 7

What’s the main antibody of the MALT?

Answer 7

IgA

Question 8

What are characteristics of the innate and adaptive immunity?

Answer 8

1. Innate - is anatomical such as: skin, Langerhans cells, MALT; it is physiological like pH, temp., soluble enzymes; and has phagocytic barriers such as inflammatory response and endocytic presentation on the cell of pathogens.
2. Adaptive - specific from antibody binding, diverse because of the combinations of light and heavy chains to make an antibody, memory, self limitation (immune system slows down when antigens decrease), and tolerant (knows self from nonself)

Question 9

Why is there so much reticular fibers in primary lymphoid organs?

Answer 9

They are very cellular organs that need the reticular fibers (type 3 collagen) to provide epithelial support, and hold cells in place in the lymphatic tissue.

Question 10

What are the antigen presenting cells, and the effector cells?

Answer 10

The antigen presenting cells are dendritic cells, macrophages. The effector cells are Cytotoxic T cells, helper T cells, and plasma cells

Question 11

Which organ has no nodules?

Answer 11

thymus

Question 12

What is the mucosa associated lymphoid tissue?

Answer 12

The MALT is a tissue that extends across most epithelium such as the lining of inner organs, and inside nodules. It consists of IgA secretions, antigen presenting cells (APCs), B cells, and helper T.

Question 13

What are the different types of tonsils?

Answer 13

1. Palatine - two of them that sit in the oropharynx; has multiple crypts; in photo
2. Lingual - around you tongue has one crypt, smaller than palatine (don’t need to identify)
3. Pharyngeal - ciliated, no crypt, covered din pseudostratified columnar.

Question 14

Describe the structure of the thymus.

Answer 14

Has cortex on outside which consists of T-cells, epithelioreticular cells, and macrophages. The medulla has differentiating T-cells, epithelioreticular cells, and the thymic blood barrier. The thymus has trabeculae and epithelioreticular pockets where T cells are exposed and help them recognize MHCs.

Question 15

How do thymocytes enter the thymus?

Answer 15

The enter via the trabecula > trickle to the medulla> between cortex and medulla these round epithelioreticular cells make various pockets to expose T cells.
In image arrows point to the epithelioreticular cells

Question 16

What are the types of thymic epithelioreticular cells?

Answer 16

In the cortex: Type 1 - separates the parenchyma from CT and has occluding junctions. Type 2 - makes up those pockets, and they’re stellate cells that have a lot of MHCs. Type 3 - more occluding junctions. In the medulla: Type 4 - has occluding junctions, and works with type 3 to form the barrier between medulla and cortex. Type 5 - same as type 2, but in the medulla. Type 6 - hassal’s corpuscle’s and produce interleukins.

Question 17

What makes up Hassal’s corpuscles?

Answer 17

dead thymic epitheiloreticular cells, keratin, keratohyalin, and lipids.

Question 18

What are langerhan cells?

Answer 18

specialized macrophages found in spinous layer of epidermis

Question 19

why are anticoagulants mixed in when taking a complete blood count?

Answer 19

blood forms clots in the presence of air, so anticoagulants are mixed in. In the complete blood count tube, RBCs fall to the bottom (hematocrit), leukocytes are on top of RBC layer, platelets are on top of leukocytes, and plasma is at the very top.

Question 20

Which stain is used for blood smear?

Answer 20

Wright’s stain

Question 21

What is diffuse lymphatic tissue?

Answer 21

lymphatic tissue as a network of cells, reticular fibers, aggregated (peyer’s patch/tonsils), or individual nodules. Peyer’s patches are the aggregates of lymph nodules below epithelial layer of columnar epithelium in small intestine.
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Question 22

What is Hassal’s corpuscles?

Answer 22

In the medulla of the thymus, a ring of lamellae formed from dead epithelioretcular cells. It secretes cytokines that help mature naive T cells.

Question 23

What is lymph node structure?

Answer 23

CT trabeculae enter cortex of lymph node which leads into subcapsular sinus, then down the cortical sinus (peritrabecular). This cortex contains lymph nodules that contain germinal centers, and the paracortex (inner cortex) has endothelial venules to also make space for lymphocytes. In the medulla the medullary cords are made up of plasma cells, macrophages, and lymphocytes surrounded by medullary sinus (consists of macrophages and reticular cells), and exits out efferent (hilum).
insert image

Question 24

What is structure of spleen?

Answer 24

surrounded by CT; red pulp contains splenic cords (which consist of reticular cells, macrophages, plasma cells, RBCs) in between the sinus cords are splenic sinuses lined by endothelial cells. White pulp is lymphatic tissue that contain central artery, and surrounded by periarteorial sheath which is made of dead T-lymphocytes.
- insert image

Question 25

What are functions of spleen?

Answer 25

RBC destruction, APC presentation, activate T cells, differentiate B cells and monitor blood

Question 26

What is difference between open and close circulation?

Answer 26

Closed is the capillaries drain into sinusoids through a tube, open is a pericellular dump of blood on sinusoids.
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Question 27

What happens in splenomegaly?

Answer 27

when people have large spleen from immature blood circulation; removal of spleen because of this so patients need to be treated with blood borne immunizations.

Question 28

Which cells are agranulocytes and granulocytes?

Answer 28

Agranulocytes = monocytes/ lymphocytes
Granulocytes = neutrophils, basophils, and eosinophils

Question 29

Neutrophil

Answer 29

• phagocytose bacteria, 3-5 nucleus lobes

Question 30

Eosinophil

Answer 30

• phagocytose parasites, bilobed nucleus (kidney), and red granules

Question 31

Basophil

Answer 31

• mediate inflammation via histamine, and blue granules

Question 32

Lymphocytes (WBC)

Answer 32

sample surroundings for foreign material; consists of B cells
T cells

Question 33

Monocyte

Answer 33

precursor to macrophage, large round cell with indented nucleus (this is how you can tell different than lymphocyte)

Question 34

Function of each immunoglobin?

Answer 34

IgG – most abundant), cross the placenta
IgA – secreted, cells that secrete concentrate along the mucous membranes
IgM – activates B cells, first produced in immune response
IgE – allergic reaction, receptors on mast cells and basophils
IgD – activates B cells