Lymphatics and the Spleen

Question 1

What tissues make up the reticuloendothelial system?

Answer 1

Monocyte/Macrophage system = Mononuclear phagocytic system

Question 2

What is the purpose of the reticuloendothelial system?

Answer 2

It is a network of phagocytic cells that forms part of the immune system (humoural and cell mediated immunity)

Question 3

What is the purpose of the lymphatic system?

Answer 3

Immune functions (lymphoid cell actions)

Lymphatic fluid (involved in circulation)

Question 4

What determines what macrophages are called?

Answer 4

Their location

Question 5

What are macrophages located in tissue called?

Answer 5

Histiocytes

Question 6

What are macrophages in the CNS called?

Answer 6

Microglia

Question 7

What are sinus histiocytes?

Answer 7

Lymph node macrophages

Question 8

Where are lymph nodes located?

Answer 8

They are typically clustered in regions around joints

Question 9

Basic principles of lymphatic system:

Answer 9

Lymph nodes cluster in regions

Lymph fluid is resorbed interstitial fluid and white blood cells

Lymphatics are similar to capillaries in structure

Lymphatics generally follow veins and fluid is returned to CVS through veins in a generally predictable pathway (Right lymphatic duct draining into right sublavian vein and thoracic duct into left subclavian vein)

Lymph nodes:
Filter lymph
Receive antigen from circulating cells
Stimulate B cells to produce antibodies

Question 10

What blood vessels do lymphatics typically follow?

Answer 10

Veins

Question 11

What blood vessels are lymph vessels structurally similar to?

Answer 11

Capillaries

Question 12

What is the name of the lymph vessel that drains lymph from the abdomen?

Answer 12

Cysterna Chyli

Question 13

Where are efferent vessels of lymph nodes located?

Answer 13

At the hilum

Question 14

Where are afferent vessels of lymph nodes located?

Answer 14

They enter at various points of the capsule

Question 15

What are the structures of the lymph node cortex?

Answer 15

in the cortex:

Follicles (B cells and Dendritic cells located here)

Mantle and Marginal zones

Question 16

What are the types of follicles in a lymph node?

Answer 16

Primary (Quiescent)

Secondary (Active, have germinal centers)

Question 17

What are the structures of the lymph node medulla?

Answer 17

Cords (plasma cells and mature B cells accumulate here where they are matured and able to be released via efferent vessels)

Sinuses

Question 18

Where in the lymph nodes are T cells located?

Answer 18

In the paracortex

Question 19

Where are mantle and marginal zones located?

Answer 19

Around follicles within cortex.

Question 20

What are the types of diseases of lymph nodes? Which ones are most important?

Answer 20

MIDNIGHT

Metabolic

*Inflammatory

Degenerative

• Neoplastic
• Infectious

Genetic/congenital

Haemodynamic

Trauma

Question 21

What is lymphadenopathy?

Answer 21

Multiplication of cells within the node (lymphatic malignancy)

Draining of an increased number of cells

Infiltration of cells from outside the node such as malignant cells

Question 22

What is reactive lymphadenitis?

Answer 22

Inflammation of the lymph nodes

Question 23

What are the changes seen in acute lymphadenitis?

Answer 23

Short time-course and tender nodes

Follicular hyperplasia (B cells) [bacterial infection and some autoimmune disorders]

Paracortical hyperplasia (T cells) [viral infections including glandular fever or shingles]

Sinus histiocytosis [nodes draining chronic infections, abscesses, or cancers]

Question 24

What are the features of a chronic lymphadenitis?

Answer 24

Longer time-course; non-tender

Often non-specific

Can reflect a condition that is chronic (chronic infection for example)

Can also occur idiopathically or in immune mediated disorders

Question 25

What are the types of neoplastic disorders that can affect the lymph nodes?

Answer 25

Primary (haematolymphoid) Secondary (Metastases)

Question 26

What are lymph nodes used for with cancer patients?

Answer 26

They provide diagnostic and prognostic information (they are useful for staging via the TNM method)

Question 27

Where is the spleen located?

Answer 27

Left upper quadrant and size of fist just under ribcage.

Question 28

What is the shape and size of the spleen?

Answer 28

Fist sized and shaped (12cm long and 150 - 200 grams)

Question 29

What surrounds the spleen?

Answer 29

Flexible, fibroelastic capsule

Question 30

What are the relations of the spleen?

Answer 30

Anteriorly (posterior wall of the stomach) Posteriorly: Left part of the diaphragm Inferiorly: Splenic flexure of left colon Medially: Left kidney Hilum is usually in contact with tail of the pancreas

Question 31

How is spleen connected to the stomach and the kidney?

Answer 31

Connected to greater curve of the stomach by the gastrosplenic ligament and to the left kidney by the splenorenal ligament

Question 32

Where does the spleen get its blood supply and how is that important in clinical practice?

Answer 32

The splenic artery goes over the tail of the pancreas to supply the spleen and so removal of the pancreas often means the spleen must also be removed.

Question 33

What are the 4 major functions of the spleen?

Answer 33

Filtering the blood (removing damaged RBCs and bacterial particles via red pulp macrophages) Antibody production (in the white pulp there is presentation of antigens to T lymphocytes) Haematopoiesis (Compensatory in settings where increased haematopoiesis is needed and important for foetal haematopoiesis) Sequestration of blood (in cases of splenomegaly can store a huge amount of blood and platelets to release them when the time is right)

Question 34

What are the 2 functionally and histologically distinct parts of the spleen?

Answer 34

White pulp: Lymphoid aggregates and macrophages Red pulp: Sinusoids and cords of Billroth.

Question 35

What makes up the red pulp?

Answer 35

Sinuses which build up to a major sinus and cords of Billroth.

Question 36

What makes up the white pulp?

Answer 36

Lymphoid aggregates and macrophages

Question 37

What are the types of diseases the spleen can encounter?

Answer 37

Congenital (accessory spleen [common] or hypoplasia/aplasia [uncommon]) Acquired (splenomegaly, trauma, infarct, neoplasms)

Question 38

What are the causes of splenomegaly?

Answer 38

Passive enlargement Secondary to infection or inflammation Hypersplenism [overactive spleen leading to cytopaenias of RBCs and platelets] Growth disorders and tumours [neoplasms, amyloidosis, sarcoidosis] Malaria most common cause Sickle cell disease

Question 39

What kind of neoplasms affect the spleen?

Answer 39

Leukemia Myeloma Lymphoma Also haemangioma/angiosarcoma

Question 40

What are accessory spleens and where are they typically located?

Answer 40

Functional extra spleens located within mesentery. If a patient has hypersplenism then this accessory spleen must also be removed.

Question 41

What happens as a result of hypersplenism?

Answer 41

Overactive spleen Peripheral cytopaenia Primary (idiopathic) Secondary to infection, alcohol, portal hypertension, systemic inflammatory disorders