20.4 The spleen removes bloodborne pathogens and aged red blood cells

What is the largest lymphoid organ?

the spleen

Approximately how large is the spleen?

about the size of a fist

Where is the spleen located?

left upper abdominal cavity, just beneath the diaphragm

What organ does the spleen curl around?

the stomach

Which artery supplies the spleen?

splenic artery

Which veins drains the spleen?

splenic vein

Through what structure do the splenic artery and vein enter and leave?

hilum

What are the two major functions of the spleen?

•immune surveillance

•blood cleansing

What is the spleen’s most important cleansing function?

removal of old and defective red blood cells

What does the spleen filter?

blood

What do lymph nodes filter?

lymph

Which cells remove old RBCs in the spleen?

macrophages

Which cells remove bloodborne pathogens?

macrophages

What happens to worn-out erythrocytes in the spleen?

they are destroyed and recycled

What important mineral is stored after RBC breakdown?

iron

Where is salvaged iron stored?

in the spleen

What blood components does the spleen store?

•platelets

•monocytes

When are stored platelets and monocytes released?

when the body needs them

During fetal life, what blood cell may be produced by the spleen?

erythrocytes (RBCs)

Four major spleen functions?

•filters blood

•iron storage

•recycles RBC parts

•stores platelets/monocytes

What surrounds the spleen?

fibrous capsule

What extends inward from the capsule?

trabeculae

What are the tow major tissue regions of the spleen?

•white pulp

•red pulp

Which spleen regions is responsible for immune functions?

white pulp

What cells dominate white pulp?

lymphocytes

White pulp surrounds what blood vessels?

central arteries

What is the primary function of white pulp?

immune surveillance and lymphocyte activation

Which spleen regions destroys old RBCs?

red pulp

Which spleen regions contains abundant erythrocytes?

red pulp

Which spleen regions contains many macrophages?

red pulp

Which spleen regions removes bloodborne pathogens?

red pulp

What structures are found in red pulp?

•splenic cords

•splenic sinusoids

What are splenic cords?

reticular connective tissue regions of red pulp

What are splenic sinusoids?

blood-filled venous spaces

Which spleen region contain splenic cords and sinusoids?

red pulp

Why is the spleen vulnerable to rupture?

it has a relatively thin capsule

What may cause splenic rupture?

•direct trauma

•severe infection

What happens when the spleen ruptures?

blood spills into the peritoneal cavity

What is a splenectomy?

surgical removal of the spleen

Which organs compensate after splenectomy?

•liver

•bone marrow