3. FUNCTION OF THE SPLEEN
OVERVIEW
‣ The spleen is an organ the size of a fist found in the left upper quadrant
(LUQ) of the abdomen, under the protection of the inferior thoracic cage
‣ It is a soft, vascularized organ with a fibro-elastic capsule
‣ It is multi-functional yet not so vital that we can’t survive without it
‣ The spleen contains two types of tissues with different functions:
‣ white pulp and red pulp
‣ Learning Goal
‣ To discuss the function of each tissue within the spleen as well as
relevant clinical conditions
4. FUNCTION OF THE SPLEEN
WHITE PULP
‣ The white pulp comprises lymph-related nodules called
malpighian corpuscles which contain:
‣ Periarteriolar lymphoid sheaths rich in T-lymphocytes
and macrophages
‣ A marginal zone, rich in macrophages
‣ Lymphoid follicles, rich in naive B-lymphocytes
5. FUNCTION OF THE SPLEEN
WHITE PULP
‣ Because of this, the white pulp of the spleen has a very
important role in the normal immune response to infection
‣ Antigen presenting cells may enter the white pulp,
resulting in activation of the T-lymphocytes stored there
‣ These in turn, activate the B-lymphocytes in the follicles,
converting them to plasma cells which then produce of
IgM antibodies initially and eventually IgG antibodies
6. FUNCTION OF THE SPLEEN
WHITE PULP
‣ Pathogens may also enter the follicles directly
‣ B-lymphocytes detect this and can then present the
antigen to the T-lymphocytes
‣ This leads to a process known as co-stimulation, in which
the two cell types activate each other
‣ so the B-lymphocyte is then able to become a plasma
cell and produce antibodies against the pathogen
7. FUNCTION OF THE SPLEEN
WHITE PULP
‣ The white pulp is also important in how the body deals
with encapsulated bacteria
‣ e.g. Neisseria meningitidis, Haemophilus influenzae and
Streptococcus pneumoniae
‣ Encapsulated bacteria tend to have a very smooth surface with
a negative charge which therefore reduces the ability of
phagocytes to attach and engulf the bacteria
‣ The B-lymphocytes in the white pulp help opsonise these
bacteria
8. FUNCTION OF THE SPLEEN
RED PULP
‣ The red pulp makes up roughly 80% of the spleen
parenchyma
‣ It is separated from the white pulp by the marginal zone
‣ The red pulp is primarily made up of tissue known as
the cords, which is rich in macrophages, and the venous
sinus
9. FUNCTION OF THE SPLEEN
RED PULP
‣ The functions of the red pulp include:
‣ Removal of old, damaged and dead red blood cells along with antigens and
microorganisms – the venous sinuses have gaps in the endothelial lining
which allows normal cells to pass through, abnormal cells remain in the cords
and are phagocytosed by macrophages
‣ Phagocytosis of opsonised bacteria by macrophages
‣ Sequestration of platelets
‣ Storage of red blood cells in case of hypovolemia, these can then be released
following an injury resulting in blood loss
‣ Prenatally, it is hematopoietic until about the fifth month of gestation when
bone marrow becomes the main site for hematopoiesis
14. FUNCTION OF THE SPLEEN
REVIEW QUESTIONS
‣ Which bacterial infections are asplenic individuals
susceptible to?
‣ Streptococcus pneumoniae, Haemophilus Influenzae,
Neisseria Mengingitidis
‣ Klebsiella Pneumoniae
‣ E coli
‣ Pseudomonas aeruginosa
15. FUNCTION OF THE SPLEEN
REVIEW QUESTIONS
‣ Which bacterial infections are asplenic individuals susceptible to?
‣ Streptococcus pneumoniae, Haemophilus Influenzae,
Neisseria Mengingitidis
‣ Klebsiella Pneumoniae
‣ E coli
‣ Pseudomonas aeruginosa
‣ Asplenic individuals are at risk of infections from encapsulated
bacteria
16. FUNCTION OF THE SPLEEN
REVIEW QUESTIONS
‣ What is the function of white pulp of the spleen?
‣ Removal of old red blood cells, antigens,
microrganisms
‣ Sequesters platelets
‣ Storage of Red blood cells
‣ Important in the normal response to an infection,
activates B and T cells
17. FUNCTION OF THE SPLEEN
REVIEW QUESTIONS
‣ What is the function of white pulp of the spleen?
‣ Removal of old red blood cells, antigens,
microrganisms
‣ Sequesters platelets
‣ Storage of Red blood cells
‣ Important in the normal response to an infection,
activates B and T cells
18. FUNCTION OF THE SPLEEN
REVIEW QUESTIONS
‣ Which is of the following are causes of splenomegaly?
‣ Edema
‣ Iron deficiency anemia
‣ Weight gain
‣ Infection, Hemolytic anemia
19. FUNCTION OF THE SPLEEN
REVIEW QUESTIONS
‣ Which is of the following are causes of splenomegaly?
‣ Edema
‣ Iron deficiency anemia
‣ Weight gain
‣ Infection, Hemolytic anemia
20. References
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‣ https://teachmephysiology.com/gastrointestinal-system/spleen/
function-of-spleen/
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