A-II Spleen: structure and function Flashcards
What are the two main types of tissue found in the spleen?
Red pulp and white pulp
Describe the location and primary function of the red pulp.
Surrounding the white pulp, destroys red blood cells
What are the main components of the white pulp organization?
Follicles containing B-cells, marginal zone (containing special macrophages), and the perifollicular zone.
What is a key feature and function of the macrophages in the marginal zone?
They are special macrophages that find blood infections and trap pathogens in the blood via special receptors.
What are the major functions of the spleen?
To filter blood, remove old or damaged blood cells (mainly red blood cells), recycle iron, remove haemoglobin from old blood cells, store red blood cells (30% of mass is blood cells), and act as a housing of antibody-producing lymphocytes
How does the spleen filter blood and remove old/damaged red blood cells?
The endothelium has stress fibers with small slits that are only small enough for healthy blood cells to pass through. Macrophages eat everything that gets stuck
What happens to the iron and haemoglobin from old red blood cells?
Iron is recycled and haemoglobin is removed and reused in new red blood cells.
SIGNR1
Expressed in spleen macrophages, binds polysaccharide antigens
SIGLEC1
Expressed in spleen macrophages, binds sialic residues
What is splenomegaly and what are some potential causes?
Splenomegaly is an enlarged spleen. Causes include infection (e.g., Malaria), obstruction of blood flow, haemolytic anemia (where the spleen works super hard), and infiltration (e.g., tumor)
What is asplenia and hyposplenia? What can cause these conditions?
Asplenia is non-function of the spleen, and hyposplenia is partial function. They can be congenital or caused by injury, disease, etc
True or False: The spleen is a primary lymphoid organ.
False; it’s a peripheral lymphoid organ
True or False: Red pulp in the spleen is mainly responsible for lymphoid matter.
False; that is the white pulp
True or False: B-cells are mainly found in follicles within the white pulp of the spleen
True
True or False: A key function of the spleen is to filter blood
True
True or False: Healthy red blood cells are trapped in the small slits of the endothelium in the spleen
False; they are flexible and can pass through
True or False: Macrophages in the spleen destroy and recycle old or damaged blood cells
True
True or False: The spleen stores approximately 70% of the body’s red blood cell mass
False; it stores 30%
True or False: The spleen plays a significant role in the production of lymphocytes and red blood cells throughout adult life
False; only when you are a fetus
True or False: Macrophages in the marginal zone of the spleen have special receptors to trap pathogens in the blood
True; SIGNR1, MARCO and SIGLEC1
True or False: SIGNR1 is a receptor on macrophages in the spleen that binds to protein antigens
False; it binds to polysaccharide antigens
True or False: Splenomegaly refers to a decreased size of the spleen
False; it refers to an enlarged spleen
True or False: Malaria can cause splenomegaly by preventing blood cells from passing through the spleen’s filter
True
True or False: Asplenia always means a complete absence of spleen function
True
True or False: Individuals with asplenia or hyposplenia have a decreased risk of infection
False; they have an increased risk
