Term
| What is the distribution of the lymph nodes? |
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Definition
Cervical (Neck)
Pulmonary (Root of Lung)
Axillary (Armpits)
Cubital (Elbow)
Aortic (Along Aorta)
Mesenteric (Along Intestinal Vessels)
Inguinal (Groin)
Popliteal (Behind Knee) |
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Term
| What cell types are present in the lymph nodes? |
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Definition
B-lymphocytes
T-lymphocytes
Plasma cells
dendritic cells
macrophages
reticular cells
mesenchymal cells
memory B, Tc, and Th cells |
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Term
| What is the basic structure of lymph nodes? |
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Definition
| Lymph nodes are bean-shaped, with convex and concave surfaces. The parenchyma consists of a peripheral cortex, adjacent to the convex surface, and a central medulla, lying near the hilum in the concave surface. The CT capsule gives off trabeculae that penetrate between the cortical nodules and subdivide the cortex. |
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Term
| What is the composition of the cortex of lymph nodes |
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Definition
The cortex has a tight packing of lymphocytes that are suspended in a reticular CT network and arranged as a layer of typical secondary lymphoid nodules
The nodules are
B-Cell Rich
Lymphoblasts in Germinal Centers
Memory Cells in Mantle Zone |
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Term
| What is the composition of the medulla of lymph nodes? |
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Definition
The medulla consists of medullary cords (cords of lymphoid tissue) separated by medullary sinuses.
The lymphocytes are small,less numerous than in the cortex, and concentrated in the cords.
The cords are rich in reticular cells and fibers and contain many plasma cells that have migrated from the cortex |
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Term
| What is the composition of the paracortical zone in lymph nodes? |
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Definition
It is a T-dependent region (athymic people essentially have an empty paracortical zone)
It lies between the cortical nodules and the medulla and contains mainly T-lymphocytes suspended in a reticular CT network
Other cells such as B-lymphocytes, plasma cells, and macrophages may be present |
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Term
| What is the subcapsular sinus? |
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Definition
A cuplike region between the capsule and cortical parenchyma in lymph nodes
It contains a mesh of reticular cells and fibers, macrophages, and follicular dendritic cells |
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Term
| What is the lymphocyte distribution in the lymph nodes? |
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Definition
B-lymphocytes are primarily found in the cortical nodules
T-lymphocytes are primarily found in the paracortical zone |
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Term
| What is lymphocyte migration? |
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Definition
Lymph nodes are not simply static mechanical filters.
Rather, they comprise dynamic, vascular and reticular connective tissue channels and scaffolds by which lymphocytes actively migrate and interact with other lymphocytes and antigen-presenting cells |
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Term
| What changes occur during lymph flow through a lymph node? |
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Definition
Added:
Immunoglobulins
Lymphocytes - programmed
Plasma Cells
Removed:
Antigens
Cellular Debris - from normal cell turnover
Lymphocytes
Bacteria
Tumor Cells |
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Term
| What does lymph node size indicate? |
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Definition
A large lymph node size indicates a lot of material is being removed from the lymph (Antigens, cellular debris
lymphocytes,bacteria,tumor cells)
If there is pain when an enlarged node is pressed down upon then infection is being fought successfully.
If there is no pain then this indicates cancer |
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Term
| What are high-endothelial venules (HEV)? |
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Definition
Postcapillary venules in paracortical zone with cuboidal endothelium
Selectin receptors on luminal surface of endothelial cells
Lymphocyte homing/ recognition, binding, transmural migration |
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Term
| What is the sequence of HEV emigration by lymphocytes? |
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Definition
Rolling: Selectins on lymphocyte microvilli form and break weak attachments, slowing lymphocytes
Tethering: Binding of selectins to receptors strengthens as lymphocytes slow further
Activation: Selectin-receptor interactions trigger chemokine release
Strong Adhesion: Chemokines initiate stronger adhesion
Transmural Emigration: Lymphocytes squeeze between endothelial cells and exit blood vessel |
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Term
| Explain T-lymphocyte recirculation |
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Definition
Blood-borne T-lymphocytes exit blood stream by diapedesis between tall endothelial cells of high-endothelial (post-capillary) venules (HEV).
Enter and migrate within perivascular channels formed by enveloping reticular cells.
Exit channels to migrate over reticular scaffold.
Exit node with lymph through sinuses and efferent vessels |
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Term
| What is the location of the spleen? |
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Definition
Upper left quadrant
Normally coveredby rib cage and difficult to palpate
in abdominal exam
Inferior tip may be palpated in patients with splenomegaly |
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Term
| What are the basic functions of the spleen? |
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Definition
Filtering blood for antigens
Erythrocyte reserve
Removing aging erythrocytes from circulation |
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Term
| What is the pathway of splenic circulation |
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Definition
IMPORTANT
Aorta
Splenic A.
Trabecular A.
Central A.
Penicillar Arteriole
Sheathed Arteriole
Red pulp sinuses
Red pulp V.
Trabecular V.
Splenic V.
Portal V |
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Term
| How does blood reach the sinusoid lumens in the spleen? |
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Definition
Open Circulation
Empty blindly into red pulp cords and percolate into
red pulp sinuses
Closed Circulation
Empty directly into red pulp sinuses
It is thought to be a combination of both theories |
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Term
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Definition
Composed of:
Periarterial Lymphatic Sheaths (PALS)
-White Pulp Surrounding Central Arteries
-T-Lymphocyte Rich (T-dependent region)
Peripheral White Pulp (PWP)
-Nodules + Marginal White Pulp
-B-Lymphocyte Rich |
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Term
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Definition
Composed of
Red Pulp Cords
-Reticular Connective Tissue Stroma
-Formed Elements of Blood
-Plasma & Memory Cells
Red Pulp Sinuses
-Endothelial Stave Cell Lining
-Very Discontinuous Basal Lamina
-Surrounded by Reticular Fibers |
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Term
| What are the different types and locations of tonsils? |
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Definition
Palatine Tonsils / Oral Pharynx
Pharyngeal Tonsil / Nasopharynx
Lingual Tonsils / Posterior Tongue |
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Term
| What are the characteristics of palantine tonsils? |
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Definition
Located in the lateral walls of the oral pharynx, below the level of soft palate
There is a bilateral pair
There are 10-20 crypts per tonsil (epithelial invaginations where antigens can get trapped)
The epithelial covering is nonkeratinized stratified squamous
There is a thick partial capsule of dense CT
It is not abnormal for these tonsils to be swollen in young children (they have dirty mouth from putting everything in sight in their mouths) |
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Term
| What happens if the palantine tonsils become too swollen? |
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Definition
| They can actually fuse with the uvula and cause the airway to be extremely constricted |
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Term
| What are the characteristics of the pharyngeal tonsil? |
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Definition
Located in the posterior of nasopharynx in midline, above level of soft palate (behind and above the uvula)
Only one
No crypts but surface is pleated
Epithelial covering is ciliated pseudostratified columnar
The capsule is thin partial CT |
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Term
| What are characteristics of the lingual tonsils? |
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Definition
Located in the posterior third of the tongue (floor of pharynx)
Small and numerous tonsils per individual
There is one crypt per tonsil
The epithelial covering is lightly keratinized stratified squamous
Lacks a definitive capsule |
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Term
| What is the function of tonsils? |
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Definition
| Tonsils and other lymphoid aggregates form a protective ring encircling inlets to digestive and respiratory systems |
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