278 Student Notebook for The Human Body: Concepts of Anatomy and Physiology
Structurally, lymphatic vessels are similar to veins of the cardiovascular system.
Both lymphatic vessels and veins have the same (how many?) layers of tissue.
Both lymphatic vessels and veins have valves to prevent the of fluids.
Lymphatic vessels converge into small organs known as lymph nodes.
Lymph Trunks and Collecting Ducts
Lymphatic trunks are formed by the merging of numerous lymphatic vessels. There are two major
lymphatic trunks.
1. Thoracic duct drains lymph from the LEFT side of the head, neck, and thorax, LEFT upper limb, and
the ENTIRE body below the diaphragm. It empties into the left vein, with which it unites.
valve prevents blood from entering the thoracic duct.
2. Right lymphatic duct drains lymph from the RIGHT side of the head, neck and thorax, and the
RIGHT upper limb. It empties into the right
Movement of Lymph
What factors influence the pressure gradients that affect the flow of lymph through the lymphatic
network?
Proteins in the fluid
muscle contraction
Breathing movements
Lymph Formation
How do proteins get into interstitial fluid? Smaller proteins can leak through the capillary wall at the arterial
end and join the interstitial fluid. They may not reenter the venous end of the capillary when most
interstitial fluid is reabsorbed. Osmotic pressure rises when proteins accumulate in the interstitial fluid.
What is osmotic pressure?.
What is typically housed in interstitial fluid? Interstitial fluid contains water and dissolved substances in
addition to small escaped from the blood.
How does interstitial fluid enter the lymphatic capillaries? Osmotic pressure in the interstitial fluid rises when
solutes or proteins accumulate in the interstitial environment. When osmotic pressure rises, reabsorption
into the venous end of the capillary slows due to a decrease in the pressure difference. The increased
osmotic pressure forces open the lymphatic capillary pores and interstitial fluid moves into the lymphatic
capillary.
At what point is the interstitial fluid called lymph?
Flow of Lymph
LEARNING OBJECTIVE 3. Describe the pathway of lymph by identifying the structures through which it passes.
As pressure increases in the interstitial space, fluid flows into lymphatic capillaries along
a PRESSURE GRADIENT Once inside the lymphatic capillaries, the pressure provides the force
needed to move the lymph along. Beyond this point, other forces assist the movement of lymph.
-pump: Skeletal muscles contract and act as a pump to squeeze both
blood vessels and lymph vessels.
pump: Breathing rhythmically squeezes and opens vessels as the
diaphragın pushes visceral organs.
Valves in lymphatic vessels allow the flow of lymph toward the heart.
