A&P 2 Chapter 20
Chapter 20-
List the functions of the lymphatic vessels.
The function of the lymphatic vessels, or lymphatic’s, is an elaborate system of drainage vessels that collect the excess protein-containing interstitial fluid and return it to the bloodstream.
Describe the structure and distribution of lymphatic vessels. The lymphatic collecting vessels have the same three tunics as veins, but the collecting vessels are thinner walled, have more internal valves, and anastomose more.
The lymphatic vessels form a one-way system in which lymph flows only toward the heart. This transport system begins in microscopic blind-ended lymphatic capillaries. These capillaries weave between the tissue cells and blood capillaries in the loose connective tissues of the body. They are absent from bones and teeth, bone marrow, and the entire central nervous system
Permeability due to two unique structural modifications:
The endothelial cells forming the walls of lymphatic capillaries are not tightly joined. Instead, the edges of adjacent cells overlap each other loosely, forming easily opened, flap like minivalves. Collagen filaments anchor the endothelial cells to surrounding structures so that any increase in interstitial fluid volume opens the minivalves, rather than causing the lymphatic capillaries to collapse.
Describe the source of lymph and mechanism(s) of lymph transport.
Once interstitial fluid enters lymphatic’s, it is called lymph
Lymphatic capillaries which empty into Lymphatic collecting vessels which empty into Lymphatic trunks and ducts
The lymphatic system lacks an organ that acts as a pump. Lymphatic vessels are low-pressure conduits, and the same mechanisms that promote venous return in blood vessels act here as well—the milking action of active skeletal muscles, pressure changes in the thorax during breathing, and valves to prevent backflow.
Lymph transport is sporadic and slow. About 3 L of lymph enters the bloodstream every 24
List the functions of the lymphatic vessels.
The function of the lymphatic vessels, or lymphatic’s, is an elaborate system of drainage vessels that collect the excess protein-containing interstitial fluid and return it to the bloodstream.
Describe the structure and distribution of lymphatic vessels. The lymphatic collecting vessels have the same three tunics as veins, but the collecting vessels are thinner walled, have more internal valves, and anastomose more.
The lymphatic vessels form a one-way system in which lymph flows only toward the heart. This transport system begins in microscopic blind-ended lymphatic capillaries. These capillaries weave between the tissue cells and blood capillaries in the loose connective tissues of the body. They are absent from bones and teeth, bone marrow, and the entire central nervous system
Permeability due to two unique structural modifications:
The endothelial cells forming the walls of lymphatic capillaries are not tightly joined. Instead, the edges of adjacent cells overlap each other loosely, forming easily opened, flap like minivalves. Collagen filaments anchor the endothelial cells to surrounding structures so that any increase in interstitial fluid volume opens the minivalves, rather than causing the lymphatic capillaries to collapse.
Describe the source of lymph and mechanism(s) of lymph transport.
Once interstitial fluid enters lymphatic’s, it is called lymph
Lymphatic capillaries which empty into Lymphatic collecting vessels which empty into Lymphatic trunks and ducts
The lymphatic system lacks an organ that acts as a pump. Lymphatic vessels are low-pressure conduits, and the same mechanisms that promote venous return in blood vessels act here as well—the milking action of active skeletal muscles, pressure changes in the thorax during breathing, and valves to prevent backflow.
Lymph transport is sporadic and slow. About 3 L of lymph enters the bloodstream every 24