Get this page’s printable bonus free, by email.
Going back to school? You may qualify for a Pell Grant of up to $7,395 a year toward a certificate or degree.
Check my grant optionsAnatomy & physiology · Study page
The lymphatic system
What it does, the route of lymph in 7 steps, the two ducts, the primary and secondary lymphoid organs and the parts of a lymph node, then 12 practice questions with every answer explained. Free, and for study only.
- 7-step lymph route
- Ducts and organs
- 12 practice questions
- No sign-up needed
CollegeCompass360 is an independent education resource. We are not a school, a testing company or a government agency.
1 · What it does
The lymphatic system in three jobs
Returns fluid to the blood
Some fluid leaves the blood capillaries and bathes the tissues. The lymphatic vessels collect the part that does not return by itself and carry it, as lymph, back into the bloodstream.
Absorbs dietary fat
Special lymph capillaries in the villi of the small intestine, called lacteals, take up fats and fat-soluble vitamins and carry them toward the blood.
Supports the immune response
Lymph is filtered as it passes through lymph nodes and other lymphoid tissue, where immune cells meet whatever the fluid has picked up.
2 · The route of lymph
From tissue fluid back to the blood, in 7 steps
Interstitial fluid
Fluid in the spaces between cells is the starting point. Once it enters a lymph capillary it is called lymph.
Lymph capillaries
Tiny vessels that begin as closed ends. Their wall cells overlap like shingles and act as one-way flaps, so fluid can get in but not back out.
Lymphatic vessels
Larger vessels with valves, like the veins. There is no pump: squeezing from nearby skeletal muscles, breathing movements and the valves keep lymph moving one way, toward the neck.
Lymph nodes
Several nodes lie along the way. Lymph goes in through afferent vessels, is filtered, and leaves through an efferent vessel.
Lymph trunks
The vessels merge into larger trunks named for the region they drain: jugular, subclavian, bronchomediastinal, intercostal, lumbar and intestinal.
Two collecting ducts
The trunks empty into the thoracic duct or the right lymphatic duct.
Subclavian veins
Each duct empties into a subclavian vein near the base of the neck, and the lymph is back in the blood.
3 · The two ducts
Which duct drains what
Thoracic duct
The left side of the head, neck and chest, the left arm and everything below the ribs on both sides, which is most of the body. It begins as a sac called the cisterna chyli.
Empties into: Left subclavian vein
Right lymphatic duct
The right side of the head, neck and chest and the right arm.
Empties into: Right subclavian vein
4 · Lymphoid organs
Primary and secondary lymphoid organs
Primary organs are where lymphocytes form and mature. Secondary organs are where mature lymphocytes meet what the body has picked up.
| Organ | Type | Where | What it does |
|---|---|---|---|
| Red bone marrow | Primary | Inside flat bones and the ends of long bones | Where all blood cells, including lymphocytes, are made. B cells mature here. |
| Thymus | Primary | In the chest, behind the sternum and above the heart | Where T cells mature. It is largest and most active early in life and shrinks with age. |
| Lymph nodes | Secondary | In clusters along lymphatic vessels, such as the neck (cervical), armpit (axillary) and groin (inguinal) | Filter lymph and give immune cells a place to meet what the lymph carries. |
| Spleen | Secondary | Upper left of the abdomen, behind the stomach | Filters blood, not lymph. Removes worn-out red blood cells and stores platelets. It has no afferent lymphatic vessels. |
| Tonsils | Secondary | Around the throat: pharyngeal (adenoids), palatine and lingual | Rings of lymphoid tissue that meet what is breathed in or swallowed. |
| Peyer’s patches | Secondary | Wall of the small intestine, mainly the ileum | Lymphoid tissue in the gut lining, part of mucosa-associated lymphoid tissue (MALT). |
| Appendix | Secondary | Attached to the start of the large intestine | Contains lymphoid tissue and counts as part of MALT. |
5 · Inside a lymph node
Afferent in, efferent out
Shape and capsule
A bean-shaped organ wrapped in a connective-tissue capsule.
Afferent vessels
Several of them bring lymph in on the curved (convex) side. “Afferent” means carrying toward.
Efferent vessel
Usually one vessel carries lymph out at the hilum, the indented side. “Efferent” means carrying away.
Cortex and medulla
The node has an outer cortex and an inner medulla, packed with lymphocytes. Macrophages and dendritic cells line the channels the lymph passes through.
6 · Practice questions
12 practice questions
Functions, the route of lymph, the two ducts, the lymphoid organs and the parts of a node, multiple choice, one at a time. Every answer is explained, and your score is free: no sign-up needed.
Question 1 of 12
What is the fluid inside lymphatic vessels called?
Bonus · unlocks with your email
The printable one-page lymphatic sheet and 10 more questions
- A one-page sheet you can print: the 7-step route of lymph, the two ducts and where each empties, and every primary and secondary lymphoid organ in one table.
- 10 more practice questions, every answer explained: the cisterna chyli, the sides of a node, lymph trunks, MALT and the node groups.
Enter your email in the box above and the bonus opens right here, and stays open on this browser.
More free study tools
Next on the same shelf
Sources
Where the facts come from
Every fact on this page is reworded from this free open college textbook. Check anything important against your course materials.
Questions
Common questions
It returns fluid from the tissues to the blood, absorbs dietary fats through the lacteals of the small intestine, and gives immune cells places to meet what the lymph has picked up.
The thoracic duct drains the left upper body and everything below the ribs, which is most of the body, and empties into the left subclavian vein. The right lymphatic duct drains the right side of the head, neck and chest and the right arm, and empties into the right subclavian vein.
Primary organs are where lymphocytes form and mature: the red bone marrow and the thymus. Secondary organs are where mature lymphocytes meet what the body has picked up: the lymph nodes, spleen, tonsils and mucosa-associated lymphoid tissue such as Peyer’s patches and the appendix.
No. The spleen filters blood. It removes worn-out red blood cells and stores platelets, and it has no afferent lymphatic vessels.
Afferent vessels carry lymph toward a lymph node and enter on its curved side. The efferent vessel carries lymph away and leaves at the hilum.
No. This is a study aid for people in anatomy and physiology courses and healthcare programs. It describes textbook structure and normal function; it does not diagnose, treat or say anything about any person’s health. Your textbook and your instructor come first.
The whole reference and the 12 practice questions with your score are free with no sign-up. An email unlocks the bonus: the printable one-page lymphatic sheet and 10 more questions.
Your next step
Studying for a program? See if grant money may help pay for it.
Answer a few quick questions about the program you want, and we will show you schools and ways to pay. Pell Grants of up to $7,395 a year may be available to students who qualify. Most students receive less, and your FAFSA and the school you attend decide.
Check my optionsCollegeCompass360 is an independent service. We are not a school and not a government agency, and we do not award aid. Whether you qualify, and for how much, is decided by your FAFSA and the school you attend.