Physiology Of The Spleen

Question 1

The spleen is the biggest lymph organ, where is it located?

Answer 1

Located in upper left portion of abdominal cavity beneath diaphragm and behind stomach.
- Like the red bone marrow it is associated with haematopoeisis.

Question 2

What is the capsule surrounding the spleen comprised of?

Answer 2

Connective tissue

Smooth muscle fibers

Question 3

The splenic capsule divides the liver into lobes:

• What is the tissue in the lobes called?
• Name the 2 kinds of tissue.

Answer 3

Tissue in the lobes of the spleen is called pulp. There are 2 kinds:
White pulp:
- White in colour
- Forms islands/nodules in the lobules containing a lot of lymphocytes.

Red pulp:

• Consists of sinuses containing large amounts of blood
• Red in colour

Question 4

Name 5 functions of the spleen

Answer 4

1. Produces RBC in foetal life
   
   • May regain functionality postnatally = Ectopic erythropoeisis
2. Blood reservoir. (Not important in men)
3. Filters blood. Macrophages remove old, damaged RBC
4. Produces and stores lymphocytes
5. Release of platelets

Question 5

What is hypersplenism?

Answer 5

Spleen becomes hyperactive destroying normal

• RBC and/or
• Neutrophils and/or
• Blood platelets

Question 6

What 3 causes of hypersplenism?

Answer 6

1. Anaemia
2. Neutropenia
3. Thrombocytopenia

Question 7

What is the function of the hormone thrombopoetin when it is isolated from the spleen?

Answer 7

Thrombocyte production

- Through Megakaryocyte proliferation

Question 8

Explain the process of the spleens blood-cleansing function in removing old cells.
- Make special mention of reticuloendothelial cells of the spleen.

Answer 8

Blood cells passing through the splenic pulp before entering the sinuses undergo thorough squeezing

 Fragile red blood cells are destroyed.
 After cells rupture, released Hb and cell stroma are digested
- By the reticuloendothelial cells of the spleen
 Products of digestion are mainly reused by the body as nutrients
- Often for making new blood cells.

Question 9

Where can large phagocytic endothelial cells be found in abundance?

Answer 9

In the pulp

- Venous sinuses are lined with similar cells

Question 10

What is the function of the spleen reticuloendothelial cells?

Answer 10

Rapidly remove debris, parasites and bacteria when blood is infected by an infectious agent.

Question 11

What is splenic enlargement in chronic infection?

Answer 11

•In many chronic infectious processes, the spleen enlarges in the same manner that lymph nodes enlarge and then performs its cleansing function even more avidly.