C10: Spleen Flashcards
the reticuloendothelial system (RE) is composed of what type of cells?
what the RE sys general function
- cells and tissue that carry out phagocytosis
- body’s major defence systems against infection… other functions depend on the organ
what does hematopoiesis occur in the RE system?
- spleen, liver, bone marrow in the fetus
- bone marrow post natally…. spleen can also form new blood cells if needed
which organs are included in the RE system
brain blood spleen, liver, thymus bone marrow lymph nodes
list the elements that make up the composition of blood
erythrocytes, thrombocytes, leukocytes and plasma
describe the function of leukocytes.
how many different types are there
- what is leukocytosis… what does it indicate
- what is leukopenia… what does it indicate
-important for immunity
5 types…. some are phagocytic and others arent
- increase WBCs
+ infection, leukaemia, malignancies, stress - low level of WBCs
+ malaria
what are the 3 process of the immune response
- body identifies a substance or antigen and determines if its foreign or not…
- if the substance is foreign, the body reacts by producing antibodies or anti-toxins
- body produces memory cells so that if it encounters the antigen again it can react more quickly
what are the 2 types of immunity and what do they produce
- Humoral: antibodies
2. Cell Mediates: anti-toxins
which organ is the largest unit of the RE system
spleen
when during fetal development does the spleen develop (wks) and from which cells
- 5 wks
- from mesoderm
when during fetal development (wks) does the spleen start performing hematopoietic function and when does it assume and adult function
- 11 wks (stops shortly after birth)
- at 5th of 6th month gestation
which area of the spleen is not covered by peritoneum
hilum
where in the body is the spleen located… which ligaments hold it in place
-left hypochondrium/LUQ
+ gastrosplenic, splenorenal, phrenocolic ligaments
whats the relationship of the spleen to the diaphragm
superior, lateral, posterior
the spleen sits medial to which structures
stomach, panc tail, splenic flexure, L kidney
the spleen sits anteior to which structures
stomach
what are the norm measurements of the spleen for an adult
how do we assess the size of a child spleen
L: up to 12 cm
W: 7-8 cm
H/AP: 3-4 cm
-formula until age 21
what are the 3 categories of splenic size?
Norm: up to 12 cm
Moderate splenomegaly: 13-18 cm
Severe splenomegaly: over 18 cm
when would the spleen appear enlarged
- in decube position (2 X size of kidney)
- is you see a flattened caudal kidney (reliable sign)
does spleen size decrease with age
yes
which vessels coverage to form the splenic vein
many smaller spleen veins @ the splenic hilum
how many arteries does the splenic artery branch into at the hilum
6
the splenic vessels course through which ligament
splenorenal
how can the removal of the spleen in childhood effect the body
can impair immune response
describe the microscopic anatomy of the spleen
-divided into lobules via projections of the c-tissue capsule
the lobules of the spleen contain what 2 pulp types?
describe the 2 types
- Red pulp
+ venous component
+ mesh network of splenic sinuses alternating with splenic cords - White pulp
+ sm islands of lymphatic tissue that contain large lymphocytes and macrophages
what does the the lymphatic tissue in the white pulp produce
whats another term for the lymphatic tissue in the white pulp
antibodies
Malpighian corpuscles
the sinusoids of the red pulp are lined with what cells?
whats another term for the splenic cords in the red pulp
phagocytic cells
-called Cords of Billroth
what are the RE functions of the spleen
- produce lymphocytes and plasma cells (antibodies)
- storage for iron and metabolites
what are the organs specific functions of the spleen
- Primary function:
+ filter blood
-act as blood reservoir, stored 50-1000 ml
-erythropoiesis/hematopoiese in the fetus
+ spleen will retain this ability but bone marrow does it after birth
what are the 2 components of blood filtration carried out in the spleen
Culling and pitting
which 2 windows can be used to scan the spleen
intercostal and subcostal (patient can be supine, RPO or decube)
what are we assess when scanning the spleen
size
position
focal abnormalities
surrounding fluid collections (cause by injury)
spleen can be used as a window to assess what organs
L kidney and panc tail
describe the echogenicity and echo texture of the spleen
texture: homogenous w/ low to medium level echos
echogenicity:
- more echogenic then L kidney cortex
- isoechoic or slightly more echogenic than the liver
what shape will the spleen have if enlarged
1/2 moon shape instead of crescent
what are 2 scanning pitfalls when scanning the spleen
- pseudoperisplenic leison
+ when the L lobe of the liver is seen superior to the spleen… mimics hematoma or abscess
+ occurs in thin patients and kids - Fluid filled stomach or tail of panc mistaken for mass
what are accessory spleens/splenules/splenuculi
- sm collection of splenic tissue near the hilum… often < 1 cm
what is a born again spleen
hypertrophy of an accessory spleen or other splenic tissue post splenectomy
what is a hematocrit
what do low levels indicate
- lab test that gives the % of RBCs per volume of blood
- indicates hemorrhage or internal bleeding
what is a hemoglobin lab test
what do low levels indicate
- hemoglobin is a protein in RBCs that transport 02
- indicates blood loss, anemia, leukemia, or can mean that the spleen isn’t functioning properly
what is thrombocytopenia… what can cause it
- low platelet count
- internal bleeding, leukemia, Vit B 12 deficiency
what is thrombocytosis… what can cause it
- increased levels
- hemorrhage, infectious disorders
what other typing of DI are used to image the spleen.. what tests do they do
- nuch med
+ RBC scan/Scintography
- radioactive tracer is injected into the blood… used to assess morphology/volume of spleen - CT
