BIOL 142 Study Guide - Midterm Guide: Gastrointestinal Tract, Endothelium, Extracellular Fluid
4 Jul 2018
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Production of Lymph
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Content of Lymph
The transport of lymph begins in microscopic blind-ended lymphatic capillaries. From
the lymphatic capillaries, lymph flows through successively larger and thicker channels -
first collecting vessels, then trunks, and finally the largest of all, the ducts.
Movement of Lymph into Lymphatic Capillaries
The transport of lymph 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. Although similar to blood capillaries, lymphatic capillaries are so
remarkably permeable that they were once thought to be open at one end like a straw.
Structure of Lymphatic Capillaries
Lymphatic capillaries are widespread but are absent from bones and teeth, bone
marrow and the entire central nervous system (where the excess tissue fluid drains into
the cerebrospinal fluid)
Location of Lymphatic Capillaries
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Function of Lymphatic Capillaries
1. 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,
flaplike mini-valves
2. 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.
What structural characteristics of lymphatic capillaries are responsible for the
permeability?
A special set of lymphatic capillaries called lacteals transports absorbed fat from the
small intestine to the bloodstream. Lacteals are so called because of the milky white
lymph that drains through them. This fatty lymph, called chyle ("juice"), drains from the
fingerlike villi of the intestinal mucosa.
Lacteals
Collecting lymphatic vessels have the same three tunics as veins, but the collecting
vessels have thinner walls and more internal valves, and they anastomose more. In
general, lymphatic a in the skin travel along with superficial veins, while the deep
lymphatic vessels of the trunk and digestive viscera travel with the deep arteries.
Lymphatic Vessels vs. Small Veins
The right lymphatic duct drains lymph from the right upper limb and the right side of the
head and thorax
Regions drained by the right lymphatic duct
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Document Summary
From the lymphatic capillaries, lymph flows through successively larger and thicker channels - first collecting vessels, then trunks, and finally the largest of all, the ducts. The transport of lymph 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. Although similar to blood capillaries, lymphatic capillaries are so remarkably permeable that they were once thought to be open at one end like a straw. Lymphatic capillaries are widespread but are absent from bones and teeth, bone marrow and the entire central nervous system (where the excess tissue fluid drains into the cerebrospinal fluid) Function of lymphatic capillaries: the endothelial cells forming the walls of lymphatic capillaries are not tightly joined. A special set of lymphatic capillaries called lacteals transports absorbed fat from the small intestine to the bloodstream. Lacteals are so called because of the milky white lymph that drains through them.
