Spleen and Thymus Flashcards
What is the Red Pulp of the spleen?
The red pulp of the spleen is made of connective tissue (cords of Billroth) and many sinuses that are engorged with blood giving it a red color
What are the two routes that blood can take through the red pulp?
The open route: blood travels from capillaries through the chords of Billroth to the splenic veins
Closed: capillaries directly to splenic veins (90%)
The majority of the blood travels through the closed system but all blood will travel the open route at least once per day
the cords of billroth “filter” the blood. Macrophages are connected by dendritic processes to the chords to “eat” any cells that might get caught in the cords.
What is the white pulp?
The white pulp of the spleen look like gray dots within the red pulp. It is made of a central artery surrounded by an eccenteric T lymphocyte collar (periarteriolar lymphatic sheath- PALS)
**“I have T with my PALS”
What are the 4 functions of the spleen?
1) Phagocytosis- old or deformed RBC
2) Cellular and humoral immunity- dendritic cells in the PALS trap and present antigens to T lmphocytes. B and T cells interact at the white pulp follicle edge to create plasma cells
3) Hematopoiesis- fetal
4) questration of blood elements-
In what part of the spleen do the B cells reside?
B cells reside in lymphoid follicles.
Lymphoid follicles are intermittent expansions of PALS and may form germinal centers as an antigenic response
what is the most common cause of infectious splenomegaly?
infectious mononucleosis
pts with hyposplenism are at an increased risk of infection d/t what types of organisms?
encapsulated bacteria
pneumococci, meningococci, haemophilus influenza
this is due to the decreased antibody production and decreased phagocytosis
What is massive splenomegaly?
What causes it?
Massive splenomegaly is when the spleen crosses the midline or extends to the pelvic cavity
Hematologic malignancies
Beta thalassemia major
Gaucher disease (lisosomal storage)
Infectious diseases
Gaucher disease
inheritance patern
s/s
deficiency
Gaucher disease is an autosomal recessive inherited disorder of lysosomal storage.
s/s: bruising, fatigue, anemia, splenomegaly
deficiencies in the enzyme glucocerebrosidase that cause a build up of the sphingolipid glucocerebroside
what is this?
who is most commonly affected?
what is the mutation?
Hairy cell leukemia
older men
BRAF
What is the classic triad of Felty’s Syndrome?
Felty’s Syndrome is a severe subset of Rheumatoid Arthritis
the triad consists of
splenomegaly
RA
Neutropenia
What is splenosis?
where is it located?
Splenosis
Implants of splenic tissue from spillage of splenic pulp in cells after trauma, splenectomy, or accidental injury to spleen during a proceedure
They are usually located in the LUQ
What is the most common cause of splenic rupture?
what are causes of a weakened spleen?
Splenic rupture is most often caused by
blunt trauma
the most common causes of a weakened spleen include
infectious mononucleosis
malaria
typhoid fever
lymphoid neoplasms
What is the treatment for a splenic rupture?
Emergency splenectomy
Thymus:
important for cell/humoral mediated immunity
derived from what embryologic structures?
Thymus
cell-mediated immunity
3rd and 4th pharyngeal pouches
what is this?
how would you describe it?
This is noninvasive thyoma
the neoplastic epithelial cells are arranged in a swirling pattern and have bland, oval to elongated nuclei
what is this?
how would you describe it?
what does it resemble?
Invasive thyoma. the neoplastic cells are polygonal and have round bland nuclei.
the appearance of invasive thyoma is almost identical to that of benign thyomas of the cortical type.
