Lymphatic System

Question 1

What is the function of the lymphatic system?

Answer 1

1. To return fluid and plasma proteins to blood
2. To return lymphocytes of the circulating pool
3. To add antibodies formed in lymph nodules

Question 2

The ultrafiltrate of blood plasma, lymph, is formed by?

Answer 2

Seepage of blood fluid across capillary walls

Question 3

What lymphatic structure is this?

• less well structured than blood capillaries
• thin-walled vessels lined with endothelium
• variable in size and calibre
• endothelium often very thin, clefts between endothelial cells
• incomplete basement membrane
• end blindly in extracellular spaces, retrieve lymph

Answer 3

Lymph capillary

Question 4

What does the flow of lymphatic vessels depend on?

Answer 4

The pressure from neighboring structures

Question 5

What lymphatic structure is characterized by these:

• relatively larger lumen than blood vessels of comparable size
• thicker wall than lymph capillaries, - intima, media, adventitia present
• valves conspicuous - insure unidirectional flow
• flow depends on pressure from neighbouring structures

Answer 5

Lymphatic vessels

Question 6

Name some lymphatic ducts (trunks)

Answer 6

Right lymphatic duct and thoracic duct

Question 7

What lymphatic structure is similar to veins? Why?

Answer 7

Lymphatic duct

-they posses valves and they have more smooth muscle in media than veins

Question 8

Where do lymphatic ducts drain?

Answer 8

Empty into great veins at the base of the neck

Question 9

What lymphoid tissue is not sharply delineated from the surrounding connective tissue?

Answer 9

Diffuse lymphoid tissue

Question 10

Where can you find diffuse lymphoid tissue underling the epithelial lining?

Answer 10

The digestive and respiratory systems

Also in lymph nodes, spleen and tonsils

Question 11

What lymphoid tissue consist of a network of reticular fibers and reticular cells?

Answer 11

Diffuse lymphoid tissue

Question 12

In diffuse lymphoid tissue, ___ of lymphoid tissue fill the spaces

Answer 12

Free cells

Question 13

What are dense aggregations of lymphoid tissue?

Answer 13

Lymphoid nodules

Question 14

Where are lymphoid nodules found?

Answer 14

In the cortex of lymph nodes and in white pulp in the spleen

(And in tonsils, appendix, under epithelium if digestive and respiratory tract)

Question 15

What is a primary nodule?

Answer 15

A round collection of tightly packed small lymphocytes

Question 16

What is a secondary nodule?

Answer 16

A spherical cluster of larger pale staining cells (germinal centre) surrounded by a cap of small lymphocytes

Question 17

What are small organs that occur along the course of lymphatic vessels?

Answer 17

Lymph nodes

Question 18

What is the function of lymph nodes?

Answer 18

Filter lymph (2k-20k cells cu. mm)
Remove undesirable cells, invading microorganisms, particulate matter
Function in immune system (lymphocyte production)

Question 19

Where are lymph nodes consistently found?

Answer 19

Mesentery, axilla, groin

Question 20

Malt
Balt
Galt

What are these?

Answer 20

Mucosal associated lymphoid tissue

Bronchial associated lymphoid tissue

Gut associated lymphoid tissue

Question 21

What does the cortex of lymph nodes contain?

Answer 21

(Outer) Primary and secondary nodules

Deep: diffuse lymphoid tissue

Question 22

Where is the thymus dependent zone in the lymphoid node?

Answer 22

Mid and deep cortex of lymph node

Question 23

The lymphocyte of the cortex of the lymph node are ____ that are seeded from the thymus.

Answer 23

Chiefly T-lymphocytes

Question 24

Where do the blood vessels of the lymph nodes enter and leave?

Answer 24

At the hilus and run in the trabeculae

Question 25

What are the characteristics of postcapillary venues in the lymph node? (High endothelial venules)

Answer 25

course radially in the deep cortex (i.e. the thymus-dependent zone),

• tall endothelial cells form their wall - no muscular coat is present
• HEV’s are traversed by small lymphocytes from the blood
• they represent the portal of entry from blood into the lymphatic circulation

Question 26

The spleen contains large amount of _____ tissue

Answer 26

Lymphoid

Question 27

What structure is a complex filter of blood which clears the blood of particulate matter and worn out cells

Answer 27

Spleen

Note: it participates in immune defense against blood-borne antigens

Question 28

What are the functions of the spleen?

Answer 28

Storage/destruction of blood cells and platelets

Hemopoiesis- production of lymphocytes
Production of myeloid elements in embryos

Hemoglobin degradation and iron metabolism. Iron is stored in the macrophages

Immune response. Production of antibodies

Question 29

Describe the capsule of the lymph nodes.

Answer 29

A connective tissue covering that thickens at the hilus. It extends into the node as trabeculae