© LECTURE NOTES – ANATOMY & PHYSIOLOGY II (A. IMHOLTZ) LYMPHATIC P1 OF 4
Includes: lymph, lymphatic vessels, lymphatic tissue, lymphatic nodules, and lymphatic
organs (lymph nodes, tonsils, the spleen, and the thymus).
Major functions of the lymphatic system are fluid balance, fat absorption, and defense
Return excess tissue fluid to the vascular system.
As blood flows thru systemic capillaries, a small amt of fluid is exuded into the
This fluid loss maintains the presence and composition of
tissue and intracellular fluid, but too much fluid loss is bad.
Return approximately 3L of fluid to the vascular system per day.
Ensures that blood volume is sufficient.
Also return any leaked plasma proteins back to the bloodstream.
Fluid within lymphatic vessels is known as lymph.
Lymph is similar to plasma except it
contains fewer proteins. It contains water, nutrients, ions, gases, wastes, and hormones.
1-way system flowing toward the heart.
Types of lymphatic vessels include: lymphatic capillaries, lymphatic collecting vessels,
lymphatic trunks, and lymphatic ducts.
Blind capillaries found almost everywhere blood capillaries are found, i.e., everywhere
tissue fluid is formed.
Areas w/o lymphatic capillaries include bones, teeth, and CNS.
Little ISF is found w/i
bones and teeth.
CNS ISF drains into the cerebrospinal fluid.
Composed of simple squamous epithelial cells that overlap and are loosely attached to
This makes the lymphatic capillaries quite permeable (much more so than blood
capillaries) and ensures that fluid is able to enter but not leave.
Fluid enters easily, as do
proteins, WBCs, pathogens, and cancer cells.
Specialized lymphatic capillaries, known as lacteals, are present in the intestinal mucosa
where they assist in absorption of dietary fat. Lymph within lacteals is known as chyle.
Lymphatic collecting vessels
Receive lymph from lymphatic capillaries.
Similar to veins (tunics with similar proportions) but contain more valves.
Superficial and deep lymphatic collecting vessels.
Pass thru lymph nodes, where lymph is “cleaned” of pathogens and cancer cells.
Formed by the union of the largest lymphatic vessels forms lymphatic trunks.
Jugular trunks drain the head and neck
Subclavian trunks drain the upper limbs, superficial thoracic wall, and mammary glands
Bronchomediastinal trunks drain thoracic organs and the deep thoracic wall
Intestinal trunks drain the intestines, stomach, pancreas, spleen, and liver
Lumbar trunks drain the lower limbs, pelvic and abdominal walls, pelvic organs, gonads,
kidneys, and adrenal glands.