Module 11 : Spleen

Question 1

reticuloendothelial system (RE system)

Answer 1

• all cells and tissue that exhibit PHAGOCYTOSIS
• major dense system against infection
• carries oy hematopoiesis
  + formation of blood cells
  + in fetus = spleen liver and bone marrow
  + not fetus = bone marrow

Question 2

RE system structures

Answer 2

• brain
• blood
• spleen, liver, thymus
• bone marrow
• lymph nodes

Question 3

composition of blood

Answer 3

• comprised of RBCs (erythrocytes), WBCs (leukocytes), platelets(thrombocytes), and plasma

Question 4

leukocytes (WBCs)

Answer 4

- play a role in immunity 
   = resistance of body to effects of a harmful agent
- leukocytosis = lots of WBCs
- leukopenia = small number of WBCs
- 5 different types
   \+ phagocytic cells
   \+ nonphagocytic cells

Question 5

immune response

Answer 5

• 3 part process
  1) body recognizes substance and decides whether foreign or not
  2) if substance is alien the body reacts by producing antibodies or anti toxins
  3) memory cells of anti bodies and antitoxins produced for the specific antigen to quicken next response

Question 6

humeral immunity

Answer 6

• antibodies

Question 7

call mediated immunity

Answer 7

• antitoxins

Question 8

spleen

Answer 8

• largest unit fo RE system
• defines mechanism
• challenging to scan due to its location

Question 9

spleen - embryology

Answer 9

• develops 5th week gestation
• arises from mesodermal cells
• hematopoietic function starting at 11 weeks gestation

Question 10

spleen - location

Answer 10

- intraperitoneal
   \+ except splenic hilum 
- encapsulated
- left hypochondriac / LUQ
- long axis in the line of the 10th rib 
- gastrosplenic, splenorenal and phrenocolic ligaments anchors spleen in place

Question 11

surface relationships

Answer 11

- superior/lateral/posterior to the spleen
   \+ diaphragm 
- medial to spleen 
   \+ stomach 
   \+ tail of pancreas
   \+ splenic flexure of colon 
   \+ left kidney 
- anterior to spleen 
   \+ stomach

Question 12

size of spleen

Answer 12

• controversial
  + length usually 11cm but not > 12cm
• normal spleen decreases in size with age

Question 13

normal spleen size

Answer 13

< 12 cm

Question 14

moderate splenomegaly

Answer 14

12-18cm

Question 15

severe splenomegaly

Answer 15

> 18 cm

Question 16

spleen is enlarged when

Answer 16

• more than twice the size of the kidney

- flattened caudal kidney

Question 17

shape of spleen

Answer 17

• crescent shape

+ concave side (medial) contains hilum

Question 18

blood supply and lymphatics

Answer 18

• vessels enter and leave at splenic hilum
• several splenic veins converge at hilum forming the splenic vein
• splenic artery branches into 6 smaller arteries at the hilum
• vessels course through the splenorenal ligament

Question 19

spleen - physiology

Answer 19

• largest organ in RE system
• NOT ESSENTIAL TO LIFE
  + conservative approach in removal

Question 20

spleen - microscopic anatomy

Answer 20

• divided into lobules via projections of the connective tissue capsule
• lobules contain pulp
  + red pulp
  + white pulp

Question 21

red pulp

Answer 21

• venous component
• splenic sinuses alternating with splenic cords (cords of billroth)
• splenic senses are spaces with blood pools

Question 22

white pulp

Answer 22

• tiny islands of lymphatic tissue consisting largely of lymphocytes and macrophages
• major site for immunological activity
  + lymphatic follicles (Malpighian corpuscles) for production of antibodies

Question 23

RE function of sleep

Answer 23

• produce lymphocytes (antibodies)
• storage
  + iron
  + metabolites

Question 24

organ specific function of spleen

Answer 24

- filter blood
  \+ culling 
  \+ pitting 
- blood reservoir (400ml)
- erythropoiesis in fetus 
   \+ hematpoiesis

Question 25

ultrasound technique

Answer 25

• overnight fst
• intercostal and subcostal windows
• supine decubitus RPO
• evaluate spleen for size position focal abnormalities and fluid collections
• sag
  + superior and inferior tips of spleen
• trans
  + always image 90’ to long axis
• usually high posterolateral approach necessary

Question 26

ultrasound appearance

Answer 26

• extremely homogeneous
• echogenicity
  + more echogenic than the cortex of the left kidney
  + isoechoic or slightly more echogenic than the liver
  + hilum disrupted by vessels
  + crescent shaped

Question 27

scanning pitfalls

Answer 27

• pseudoperisplenic lesion
  + thin patients and children
  + left lobes of liver identified superior to spleen
  + mimics subcapsular hematoma abbess
• fluid filled stomach or tail of panc mistaken for mass

Question 28

variants

Answer 28

• accessory spleen/splenule/splenuculi
  + small, found near hilum
• born again spleen
  + hypertrophy of accessory spleen or other splenic tissue after splenectomy

Question 29

lab tests

Answer 29

• hematocrit
• hemoglobin
• white blood cells
• leukocytosis
• leukopenia
• platelets

Question 30

hematocrit

Answer 30

• percentage of RBCs per volume of blood

- decrease indicates hemorrhage of internal bleeding

Question 31

hemoglobin

Answer 31

• protein in RBC responsible for transporting oxygen

- decreases in acute blood loss

Question 32

white blood cells

Answer 32

• leukocytes

- protect against infection

Question 33

leukocytosis

Answer 33

• increases

- acute infection

Question 34

leukopenia

Answer 34

decreased count

Question 35

platelets

Answer 35

• thrombocytes
• promote coagulation
• usually genetic

Question 36

nuke med

Answer 36

• red blood cell scan