(M) Lec 3: Lymphatic System Flashcards
Also called immune system
Lymphatic System
These are aggregates of lymphocytes in different regions of the body
Lymphoid Tissue
Parenchyma of the system
Lymphocytes
Stroma of the system
Reticular tissue / Reticular cells and fibers
Other cells found in the system
Plasma cells, macrophages, neutrophils, eosinophils
Location of parts of the Lymphatic system
lamina propria of respiratory and digestive system thymus, spleen, lymph node, tonsils
Types of lymphocytes according to size
Small, medium, large
This system protects the internal environment from invasion and damage by foreign substances, cells or microorganisms
Lymphatic system
These refer to which cell:
- Small, spherical or oval
- Large rounded nucleus or slightly indented on one side
- Narrow non-granular cytoplasm
Lymphocytes
Type of lymphocyte according to size
- Majority of cells
- 6-9 um
- Dark staining
Small lymphocytes
Type of lymphocyte according to size
- 9-15 um
- Pale
- Lymphoblasts
Large lymphocytes
What sensitizes small lymphocytes?
Antigenic stimulation
small lymphocytes recognize foreign proteins and they store this info
Referred to as memory cells
T and B lymphocytes
A memory cell that directly attack the foreign organism
t-lymphocyte
The lymphocytes in the thymus contains:
A. T Lymphocytes
B. B Lymphocytes
C. AOTA
D. NOTA
A (100%)
The lymphocytes in the bone marrow contains:
A. T Lymphocytes
B. B Lymphocytes
C. AOTA
D. NOTA
C (10% of the T Lymph and 90% of the B Lymph)
The lymphocytes in the blood contains:
A. T Lymphocytes
B. B Lymphocytes
C. AOTA
D. NOTA
C (70/30)
The lymphocytes in the spleen contains:
A. T Lymphocytes
B. B Lymphocytes
C. AOTA
D. NOTA
C (45/55)
The lymphocytes in the Lymph nodes contains:
A. T Lymphocytes
B. B Lymphocytes
C. AOTA
D. NOTA
C (60/40)
These are programmed to recognize and react with specific types of antigen
Lymphocytes
What are the classifications of lymphoid tissue?
- Loose lymphoid tissue
- Dense lymphoid tissue
- Nodular lymphoid tissue
Trachea, Esophagus, Internodular deep cortical and medullary sheaths of the spleen, Internodular regions of the tonsils and Peyer patches
These are example of which lymphatic issue?
Loose lymphatic tissue
Type of lymphatic tissue
- Few lymphocytes
- Irregularly and loosely scattered
- Stroma: reticular cells and reticular fibers
Loose lymphatic tissue
Type of lymphatic tissue
- Lymphocytes are abundant and closely packed
- Examples: Ileum, Colon, Vermiform appendix
Dense LT
Also known as lymphoid follicles
Nodular LT
Type of lymphatic tissue
- Compact, circumscribed aggregations of lymphocytes
- Aka lymphoid follicles
- Not permanent structures
- Solitary lymphoid nodules
Nodular LT
Found in:
Lamina propria of the digestive, respiratory, and urinary tract
- Aggregates are found in Walls of the ileum called Peyer patches, Veriform appendix
Nodular LT
Type of lymphatic tissue
characterized as compact, circumscribed aggregations of B-cells forming lymphatic follicles or lymphatic nodules
Nodular LT
Refers to:
Aggregates of uniform cell density and staining; Has not encountered any antigen yet; No stimulation of any antigen
Primary lymphoid nodule
Refers to:
Aggregates with larger, more euchromatic cells centrally; Has already encountered an antigenic stimulation
Secondary lymphoid nodule
Its germinal center is a central, pale staining portion of a secondary nodule. This is composed of large activated B
lymphoblasts (centroblasts)
Tonsils
The peripheral, dark staining portion of lymphatic nodules is called the __________.
mantle/corona
Part of tonsil
➢ Smaller, naive lymphocytes pushed to the sides
➢ This is due to the rapid proliferation of activated B lymphoblasts
➢ Crowded together peripherally
➢ This is made up of small lymphocytes with dark staining nucleus and closely packed cells
Mantle/corona of the tonsils
Two classifications of lymphoid organs
Primary and Secondary
Example of primary lymphoid organ
Bone marrow and Thymus
Example of secondary lymphoid organs
➢ Spleen
➢ MALT (Mucosa-associated lymphoid tissue)
o Tonsils
o Peyer patch
Cells of the major lymphoid lineages mature and become functional in two different central or ______________
primary lymphoid organs
After activation in the primary, B and T cells circulate to which type of lymphoid organs?
Secondary
➢ Site of T-lymphocyte differentiation
➢ Selective removal of T-cells reactive against self antigens
Thymus
- Bilobed structure in mediastinum
- Remains large & active in T cell production until puberty
- Undergoes involution
Thymus
Two parts of thymus
Cortex and medulla bitch
Part of thymus
- Darkly basophilic
- Plenty of lymphoblasts aka thymocytes
- A peripheral zone of dense lymphatic tissue consisting of T-lymphocytes
- Do not form lymphatic nodules
Thymic cortex
Part of thymus
- The blood supply of this area consists only of capillaries.
- This area is an active site of lymphocyte production.
Thymic cortex
These cells found in the thymic cortex are stellate in shape, with scanty acidophilic cytoplasm and a large, oval nucleus.
Epithelial reticular cells
Part of thymus
- Composed of few pale staining lymphocytes.
- The reticular cells here are extremely pleomorphic and have a more acidophilic cytoplasm.
Thymic medulla
In the thymic medulla, some reticular cells are rounded; others are flattened
or wrapped around one another giving rise to the structures called __________.
Thymic corpuscles or Hassall’s bodies
These are large aggregates of epithelial cells arranged concentrically that secrete cytokines; characteristic feature of thymus
Hassall’s bodies
MALT stands for?
Mucosa-associated lymphoid tissue
T or F: MALT is an actual organ
False (a connection of lymphoid tissue)
- Large and diffuse collections of:
➢ Lymphocytes
➢ IgA-secreting plasma cells
➢ Antigen presenting cells
➢ Lymphoid nodules
MALT
Tonsil that is:
➢ Stratified Squamous Non-Keratinized Epithelium
➢ Tonsillar crypts → 10 to 20 deep invaginations
➢ Partial capsule of dense CT
Palatine
How many invaginations are tonsillar crypts?
10 - 20
Tonsil that is:
➢ Stratified Squamous Non-Keratinized Epithelium
➢ with crypts
➢ No distinct capsule
Lingual
Tonsil that is:
➢ Pseudostratified Columnar Ciliated Epithelium with Goblet cells
➢ Thin capsule, shallow infoldings; no crypts
Pharyngeal tonsil
These are nodular aggregates only found in the ileum
Peyer’s patches
➢ Commonly found in the lamina propria of the mucosa and some in the submucosa
➢ No underlying CT capsule
➢ Some lymphocytes are densely packed while others form aggregates of nodules
Peyer patches
- Short, small-diameter projection from the cecum
- Lamina propria and submucosa filled with lymphocytes and lymphoid follicles
- Lumen may contain bacteria of large intestines
Appendix
- Bean-shaped encapsulated structures
- 1.0 cm by 2.5 cm
- Along lymphatic vessels
- 400-450 nodes
Lymph node
➢ Defend against the spread of microorganisms and tumor cells
➢ Provide enclosed environments for:
o Antigen presentation
o Development of plasma cells secreting non-IgA antibodies
Lymph node
Part of lymph node:
o Afferent lymphatics enter
Convex surface
Part of lymph node:
o Concave depression
o Efferent lymphatic leaves
o A, V, N penetrate the organ
Hilum
Part of lymph node:
o Dense connective tissue
o Trabeculae extend internally through which the blood vessels branch
Capsule
Part of lymph node:
o Ensure unidirectional lymph flow
Valves
Three major regions of the lymph node
Cortex, Paracortex, Medulla
Region of lymph node
- Receiving lymph from the afferent lymphatics
- Lymphoid nodules
Cortex
Region of lymph node
- Where most lymphocytes enter
- Lacks B-cell lymphoid nodules
- Lymphoid tissue rich in T cells
Paracortex
Region of lymph node
Has medullary sinuses and cords
Medulla
Medulla of lymph node
➢ Darker portion
➢ Masses of lymphoid tissue
➢ Contain T and B lymphocytes, plasma cells
Medullary cords
Medulla of lymph node
➢ Lighter portion
➢ Dilated spaces
➢ Discontinuous endothelium
➢ Final lymph filter
Medullary sinuses
- Located at the Left Upper Quadrant (LUQ) of the abdomen
- 12 x 7 x 3 cm
- Filled with dense CT capsule/ fibroelastic capsule
Spleen
- Two regions: White pulp and Red pulp
- Functions:
➢ Defense against blood-borne antigens
➢ Main site of old erythrocyte destruction
➢ Production site of antibodies and activated lymphocytes
Spleen
The lymphatic nodule of spleen
White pulp
20% of the spleen; consist of lymphoid nodules and the periarteriolar lymphoid sheaths (PALS)
Region of spleen
- Associated with a central arteriole
- Enclosed by Periarteriolar lymphoid sheath (PALS) of T cells
White pulp
Region of spleen
- Filters blood
- Removes effete erythrocytes
- Recycles hemoglobin iron
Red pulp
What are the two portions of the red pulp of the spleen?
Splenic cords of Billroth
Splenic sinusoids
What does NRMF stand for?
Nicanor Reyes Mother Fucker
Cells that line the splenic sinusoids that allow the separation of healthy RBCs from effete RBCs
Stave cells
Stroma of thymus
Epithelial reticular cells and macrophages
Where are hassall’s bodies found?
Thymic medulla
T or F: Hassall’s corpuscles in adults are larger than those in the child
True
Two types of lymphatic vessels in the lymph node
Afferent and Efferent
These are the reticular tissue, lymphocytes, plasma cells, and macrophages in the lymph nodes
Stroma
In lymph nodes, which is paler in staining, cortex or medulla?
Medulla
Familiarize the lymphatic pathway and sinuses
- afferent vessels-carries lymph to the organ
- lymph then goes to the subcapsular sinus
- from the cortical sinus into the medullary sinus
- efferent lymphatic vessels
The humoral immune response of the lymph node is a property of which cells?
B lymph and plasma
The cellular immune response of lymph nodes is a property of which cell?
T lymph (Its differentiation and activation)
This organ has no afferent vessels nd no lymph sinuses; largest lymphoid organ
Spleen
T or F: PALS consists of B lymph while germinal center consists of T lymph
False (baliktad)
Part of spleen
→ forms periarteriolar lymphoid sheaths (PALS)
→ found around the arteries; leaves the trabeculae to penetrate the parenchyma and may contain germinal centers
→ PALS consists of T-lymphocytes while germinal centers consist of B-lymphocytes
→ reticular tissue forms an irregular and loose CT
→ lymphocytes are small and medium-sized with the occasional presence of plasma cells and macrophages
White pulp
Part of spleen
→ surrounds the white pulp
→ consists of plexuses of venous sinuses
→ subdivided into anastomosing cords called the Splenic Cords of Billroth (pulp cords; diffuse lymphatic tissue)
→ contains a large number of RBCs that fill the lumen of the sinuses and infiltrate the splenic cords
→ responsible for its color in fresh preparations
→ contains macrophages, erythrocytes, platelets, and a few plasma cells
Red pulp
a peripheral, dark-staining portion of the lymphoid nodules; small lymphocytes with a dark-staining nucleus and closely packed cells
Corona
Functions of this organ:
Cellular/cell-mediated immunity
Homograft rejection
Delayed hypersensitivity
Graft vs. host reaction
Immune response to fungi, bacteria, and virus
Thymus
Functions of this organ:
Graveyard for worn out RBCs
Reservoir for RBCs
Formation of lymphocytes
Removal of particulate matters in circulation
Immune response to bacteria, viruses, and foreign macromolecules
Spleen
These are deep invaginations at various places on the surface of tonsils
Tonsillar cyrpts
Part of lymph node that is involved in functional differentiation of B lymphocytes
Germinal center
The germinal center of a nodular LT is involved in the differentiation of which type of lymphocyte?
B lymphocytes
LE of tonsils
Stratified squamous non-cornified epthelium
Capsule of thymus is made of which specific subtype of tissue?
Loose CT
Which part of the larynx is palatine tonsil found?
Oropharynx
Type of lymphatic tissue, palatine tonsil
Dense and nodular LT
WBCs found in saliva
Lymphocytes and neutrophil
T or F: Palatine tonsils and lingual tonsils are the same
False
Where are lymphocytes formed?
Bone marrow
Receptors of B lymphocytes
Immunoglobulins
Receptors of T lymphocyte
T-cell receptors
Type of lymph node
Found in lamina propria of the digestive, respiratory, and urinary tracts
Solitary lymphoid nodules
Found in walls of the ileum–Peyer’s patches and the vermiform appendix
Aggregates of lymphoid nodules