Lecture: Lymphatic System

Question 1

What are the 3 functions of the lymphatic system?

Answer 1

1) fluid recovery
2) immunity
3) lipid absortion

Question 2

Describe lymph capillaries.

Answer 2

absorb interstitial fluid;
associated with blood capillaries;
highly permeable ECs
-anchored by fine filaments
-EC opened during swelling

Question 3

Give an example of a specialized lymphatic capillary.

Answer 3

lacteals: absorb/transport dietary lipids

Question 4

Contrast lymphatic vessels and veins.

Answer 4

thinner walls

more valves

Question 5

What is the function of lymphatic trunks?

Answer 5

to drain a major portion of the body

Question 6

Name all 6 lymphatic trunks.

Answer 6

1) lumbar
2) intestinal
3) intercostal
4) bronchomediastinal
5) subclavian
6) jugular

Question 7

Explain collecting ducts.

Answer 7

largest lymphatic vessels, located in thoracic region;

1) right lymphatic duct empties into right subclavian
2) left lymphatic duct, or thoracic duct, empties into left subclavian

Question 8

Name 4 mechanisms by which the flow of lymph is promoted.

Answer 8

1) skeletal muscles
2) smooth muscles contractions in vessels
3) breathing
4) pulsing of arteries (share common CT)

Question 9

Name 6 lymphatic cells.

Answer 9

1) natural killer (NK) cells
2) T lymphocytes
3) B lymphocytes
4) macrophages
5) dendritic cells
6) reticular cells

Question 10

Explain lymphatic tissue.

Answer 10

clusters of lymphocytes in CT;

1) diffuse lymphatic tissue
- callled mucosa-associated lymphatic tissue (MALT) in body passages open to the exterior
2) lymphatic nodules (follicles): dense lymphocytes and macrophages
- lymph nodes, tonsils, appendix, Peyer’s patches (small intestine)

Question 11

Define: lymphatic organs.

Answer 11

well-defined anatomical sites with CT capsules separating lymphatic tissues

Question 12

Explain and give 2 examples of primary lymphatic organs.

Answer 12

sites where B and T lymphocytes become immunocompetent (able to recognize and respond to pathogens);
ex. red bone marrow & thymus

Question 13

Explain and give 3 examples of secondary lymphatic organs.

Answer 13

sites where immunocompetent cells migrate after maturation;

ex. lymph nodes, tonsils, spleen

Question 14

Where is red bone marrow located and what is its function within the lymphatic system?

Answer 14

axial skeleton, proximal head of humerus and femur in adults;
function: hemopoesis;
reticular cells secrete colony-stimulating factors that induce formation of leukocytes

Question 15

Describe the composition of the thymus.

Answer 15

2 lobes:
cortex: dense lymphocytes;
medulla: sparse lymphocytes;
reticular epithelial cells: produce thymosin & thymopoietin

Question 16

What are the functions of lymph nodes?

Answer 16

filter lymph;

activate B and T cells

Question 17

Describe the composition of lymph nodes.

Answer 17

2 layers:
cortex
-contains lymphatic nodules with germinal centers where B cells differentiate;
medulla
-branching network of medullary cords composed of lymphocytes, plasma cells, macrophages, and reticular cells

Question 18

Describe tonsils.

Answer 18

lymphatic tissue at the pharynx entrance which guards against ingested and inhaled pathogens;
tonsillar crypts are deep pit in the epithelium which trap bacteria and move it into the lymphatic tissue, where it is destroyed

Question 19

Describe the spleen.

Answer 19

largest lymphatic organ;
parenchyma has 2 types of tissue:
1) white pulp: lymphocytes/macrophages ready for a quick immune response
2) red pulp: engorged erythrocytes- “erythrocyte graveyard”