Histology of the Immune System Flashcards
What are the two main functions of the immune system?
Make cells and complements to keep bad things out, and recognize non-self from self.
What are the primary lymphoid organs?
bone marrow (both T and B made here), and thymus (only T cells mature here)
What are secondary lymphoid organs?
spleen - blood filter, and lymph node - lymph filter
What part of the antigen to antibodies recognize?
The epitope, which is specific domain of the antigen
What is difference between humoral and cellular immunity?
when antibody removes the antigen it is humoral, when cell removes and presents it is cellular.
What can you find in lymphatic nodules?
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)
What’s the main antibody of the MALT?
IgA
What are characteristics of the innate and adaptive immunity?
- 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.
- 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)
Why is there so much reticular fibers in primary lymphoid organs?
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.
What are the antigen presenting cells, and the effector cells?
The antigen presenting cells are dendritic cells, macrophages. The effector cells are Cytotoxic T cells, helper T cells, and plasma cells
Which organ has no nodules?
thymus
What is the mucosa associated lymphoid tissue?
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.
What are the different types of tonsils?
- Palatine - two of them that sit in the oropharynx; has multiple crypts; in photo
- Lingual - around you tongue has one crypt, smaller than palatine (don’t need to identify)
- Pharyngeal - ciliated, no crypt, covered din pseudostratified columnar.
Describe the structure of the thymus.
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.
How do thymocytes enter the thymus?
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
What are the types of thymic epithelioreticular cells?
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.
What makes up Hassal’s corpuscles?
dead thymic epitheiloreticular cells, keratin, keratohyalin, and lipids.
What are langerhan cells?
specialized macrophages found in spinous layer of epidermis
why are anticoagulants mixed in when taking a complete blood count?
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.
Which stain is used for blood smear?
Wright’s stain
What is diffuse lymphatic tissue?
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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What is Hassal’s corpuscles?
In the medulla of the thymus, a ring of lamellae formed from dead epithelioretcular cells. It secretes cytokines that help mature naive T cells.
What is lymph node structure?
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).
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What is structure of spleen?
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.
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