Introduction to the Lymphatic System

Question 1

Describe the major components and functions of the lymphatic system.

Answer 1

Functions to return tissue fluid back to bloodstream, transport fat from intestines to bloodstream and immune defense.
Components- Lymph (fluid), lymphatic vessels and lymphatic tissues/organs

Question 2

Explain the general process of lymph formation and the return of tissue fluid to the bloodstream.

Answer 2

Pressure in capillary beds pushes plasma out and osmotic pressure is only able to take 85% back into capillaries. 15% stays in tissue as interstitial fluid. Extra IF makes its way to lymph capillaries as lymph. Lymphatic vessels carry it to either Right Lymph Duct or Thoracic Duct to re-enter blood.

Question 3

Describe the general characteristics and functions of lymph, lymphatic capillaries and lymphatic vessels.

Answer 3

Lymph is colorless fluid that is similar to blood plasma with less proteins.
Lymphatic capillaries- single overlapping endothelial cells anchored throughout highly vascularized body tissues; carry lymph to larger vessels and fat.
Lymphatic vessels- similar to vein (one way valve) three layers thick they connect with lymph nodes and bring lymph to either one of the two main channels of delivery to bloodstream.
3 Lymphatic vessel Layers:
1. tunica interna - endothelium and valves
2. tunica media - elastic fibers and smooth muscle
3. tunica externa - thin outer layer

Question 4

Explain the steps in the flow of lymph from tissues back to the bloodstream.

Answer 4

Lymphatic capillaries -> collecting vessels (lymph vessels) -> 6 lymphatic trunks -> 2 collecting ducts (right lymphatic and thoracic) -> subclavian veins (either right or left from respective duct)

Question 5

Compare and contrast the lymphatic drainage of the thoracic duct and right lymphatic duct.

Answer 5

Right lymphatic duct- drains the upper right quadrant of the body
Thoracic duct- drains the rest of the body: lower half and upper left quadrant

Question 6

Explain the major factors that influence the flow of lymph.

Answer 6

• Smooth muscle in lymph vessels
• Compression of vessels by muscle contraction
• Negative pressure in thorax due to respiratory movements
• Arterial pulsations
• Gravity

Question 7

Describe the role of the lymphatic system in the absorption and transport of fats.

Answer 7

Lacteals (specialized lymph caps) are found in villi in the mucosa of small intestine.
Lacteals absorb fat and fat soluble vitamins.
Lymph in lacteals with fat is called chyle which is carried to left subclavian vein.

Question 8

Describe the structural and functional characteristics of lymph nodes.

Answer 8

Structure- multiple afferent vessels carry lymph to nodule. One efferent vessel leaving. Enclosed by fibrous capsule.
Function- acts as a filter and houses lymphocytes for immune response