spleen Flashcards
What is the largest lymphoid organ in the body?
The Spleen
list Lymphoid Organs
- Thymus
- Lymph node
- Spleen
- Tonsils
- Spleen only lymphoid organ involved in ………….
- making Spleen Important in defense against …………..
- Spleen is a production site of ………………
- filtration of blood,
- blood borne antigens.
- antibodies& activated lymphocytes
The Spleen
1. is the …… lymphoid organ in body
2. It is formed of: ……….
3. Differs from lymph node as:
……………..
1.largest
2.
- Stroma
- Parenchyma
3.
- It is not divided into cortex and medulla
- No afferent lymphatic
illustrate structure of Stroma of Spleen
- Capsule:
formed of :
- C.T fibers &myofibroblasts.
- Covered by peritoneum.
-Capsule thickened at hilum. - Trabeculae:
divide spleen into:
irregular compartments (same
structure as capsule). - Reticular C.T: reticular fibers and cells
illustrate structure of Parenchyma of spleen.
a. White pulp:
Consists of:
1. Periarterial lymphatic sheath PALS
2. lymphoid nodules usually secondary
with germinal center
3. Marginal Zone
b. Red pulp:
1. Splenic sinusoids
2. Splenic cords
discuss PALS
- It is the Lymphoid tissue immediately surrounding central arteriole
- Formed of: T lymphocytes mainly
- It is termed Thymus dependent zone
illustrate Lymph nodules of white pulp
1.Rounded lymphoid tissue along the course of PALS
2. Each nodule is traversed by central arteriole (follicular artery) occupies eccentric position.
3. Formed of:
B lymphocytes, MQ, Follicular dendritic cells.
what’s the marginal zone of white pulp of parenchyma of the spleen ?
- Border between white & red pulp.
- Composed of: many MQ, B lymphocytes, plasma cells Dendritic cells.
- Contains numerous wide blood sinuses (Marginal sinuses)
- Circulating T & B lymphocytes leave blood to enter white pulp e
5.Marginal sinus.
It is the first site of contact between
the blood and the splenic parenchyma
illustrate blood flow in the spleen
1.Splenic artery enters spleen at hilum
2.It divides into trabecular arteries
3.Which gives central arterioles
4.Central arterioles in white pulp become surrounded by PALS .
5.PALS is surrounded by lymph nodules.
- formation of lymph nodule is due to ………located within PALS by a trapped antigen from blood,
-in growing nodules, the central arterioles are pushed to ………..position)
- activation of B lymphocytes
- eccentric
about Splenic sinusoids
1. shape ……
2. Surrounded by …….
3.Supported by ………
4. lined by……….
5. - ……associated with wall of sinusoids
- separated with…………..
6.Its processes extend between
Endothelial cells to monitor…………
- fusiform in shape &wide lumen
- discontinuous basement membrane
- strands of basal lamina that loop around the sinuses perpendicular to the long. axis of the sinusoids
- -long and fusiform endothelial cells
- wide spaces (resembling staves of a barrel) which allow exchange of fluids & passage of cells between sinusoids & cords.
- MQ .
- bl. Ag.
about Splenic cords (Cords of Billroth)
1. It is the soft tissues between ………
2. The cords consist of a……….
3. containing:……………
- the white pulp & the blood sinusoids.
- network of reticular cells & fibers
- All elements of blood (RBCs, WBCs & platelets)
- Macrophages
- Plasma cells
- Dendritic cells
- Lymphocyte
illustrate Blood circulation of the spleen
- Splenic artery enters spleen at hilum
- It divides into trabecular arteries
- Which gives central arterioles
- Central arterioles in white pulp become surrounded by PALS & give branches to form marginal sinus in marginal zone.
- Central arterioles leave white pulp to give penicillararterioles
- Penicillar ends in terminal arterioles then blood enters splenic sinusoids to pulp veins ..to tabecular veins …to splenic veins
Theories of splenic circulation. discuss
- Closed circulation: Penicillar arterioles(ellipsoids) pour blood into blood sinusoids
- Open circulation: Penicillar arterioles are open ended and blood passes from
them to stroma of red pulp…. Blood enter sinusoid through spaces between
endothelial cells - Mixed circulation (Open –closed theory of Kinsley)
