Lymphatic System Trivia
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89 free Lymphatic System trivia questions with answers — science & nature quiz, new questions added Oct 2026.
This lymphatic system trivia quiz covers the body's open drainage network from end to end: where lymph comes from, how it moves without a pump, the lymph nodes and ducts it passes through, and the organs that build and train its lymphocytes, including the thymus, the spleen, the tonsils and red bone marrow. It also reaches into the clinic and the history books: lymphedema and lymphoma, the lacteals that carry fat from the gut, Hippocrates' one-sentence mention, Gaspare Aselli's dogs, Jean Pecquet's thoracic duct and the bitter 17th-century priority dispute between Olaus Rudbeck and Thomas Bartholin. The early questions suit an anatomy or biology classroom; the later ones reward anyone who has sat through a physiology course. Every answer was checked against encyclopaedia entries before publishing.
30 of 89 questions with answers and explanations. Play the quiz
Q 01The lymphatic system is considered part of which other body system?
Immune
Immune. The vessels that drain leaked fluid back to the blood double as highways for infection-fighting white cells, and the nodes along the route act as checkpoints where invaders are trapped.
Q 02Like veins, lymph vessels are fitted along their length with which structures?
Valves
Valves. They keep lymph flowing one way, and they sit so close together that lymph vessels look like strings of beads.
Q 03Lymph originates from which fluid that leaks out of blood into the tissues?
Interstitial
Interstitial fluid bathes every cell, and lymph is the very same liquid under a new name: it only becomes lymph at the moment it slips inside a lymph capillary.
Q 04Which of these vitamins travels from the gut in the lymph, with dietary fat, rather than straight into the blood?
Vitamin D
Vitamin D. Like vitamins A, E and K it dissolves in fat, so it hitches a ride with digested fat into the gut's lymph vessels instead of going straight into the bloodstream.
Q 05About how much leaked fluid does the lymphatic system return to the bloodstream each day?
3 litres
3 litres. Around 20 litres of fluid seep out of the blood capillaries every day; the capillaries take 17 straight back, and the lymphatic system has to collect the rest.
Q 06Lymph is described as very similar to which component of blood?
Plasma
Plasma. Lymph begins as the liquid part of blood seeping out through the capillary walls, and because the red cells are too big to follow, it runs clear and colourless instead of red.
Q 07Where in the adult body do all lymphocytes begin life?
The bone marrow
The bone marrow. Every lymphocyte starts there as a stem cell, but only B cells stay to grow up: future T cells leave early and finish their training in the thymus.
Q 08Which clusters of lymphoid tissue in the wall of the small intestine are named after a 17th-century Swiss anatomist?
Peyer's patches
Peyer's patches. Their surface is studded with M cells, which grab samples of whatever is passing through the gut and hand them to the lymphocytes waiting underneath.
Q 09What does the acronym MALT stand for?
Mucosa-associated lymphoid tissue
Mucosa-associated lymphoid tissue guards the moist linings where germs most often get in, such as the airways and the gut. Unlike a lymph node it has no capsule: just loose clusters of lymphocytes under the surface.
Q 10The large left lymphatic duct draining most of the body is known by what name?
Thoracic
Thoracic. The body's lymph drainage is lopsided: this single duct serves both legs, the abdomen and the whole left side, while its partner handles only the right arm and the right side of the head and chest.
Q 11The lymph ducts empty into which veins to return lymph to the bloodstream?
Subclavian
Subclavian. The two lymph ducts join these veins at the base of the neck, one on each side; if the fluid never made it back to the blood there, the body's tissues would swell with it.
Q 12With no central pump, what mainly moves lymph through the human body?
Muscle contractions
Muscle contractions. Lymph is squeezed along from outside by the body's ordinary movements, breathing included, and from inside by muscle in the walls of the larger vessels themselves.
Q 13Which epidemic disease is named from the Greek word for groin, after the swollen lymph nodes it causes there?
Bubonic plague
Q 21A 2009 mouse study found the spleen holds a reserve army of which white blood cells?
Monocytes
Monocytes. More of them wait in the spleen than circulate in the blood, and when the heart is damaged they pour out together, travel to the injury and help it heal.
Q 22Which of these animals has dedicated "lymph hearts" that beat to pump lymph into its veins?
Frogs
Frogs. Amphibians and reptiles have small beating lymph hearts spaced along their lymph vessels to push the fluid on, but mammals, people included, have none at all.
Q 23How does the spleen release its reserve of red cells during acute blood loss?
It contracts
It contracts. The same squeeze happens when you hold your breath: the spleen shrinks and pushes extra red cells into the blood, a trick humans share with diving seals.
Bubonic plague. Bacteria from a flea bite travel along the lymph vessels to the nearest node and multiply there until it balloons into a painful swelling called a bubo.
Q 14Where in the lymphatic system do deep pits, called crypts, deliberately trap germs so the body can learn to fight them?
The tonsils
The tonsils. The pits are no design flaw: they invite germs in on purpose, giving a child's defences an early look at common infections at the very spot where food and air enter the body.
Q 15Which extra primary lymphoid organ, absent in mammals, do birds have?
Bursa of Fabricius
Bursa of Fabricius. B cells were first worked out in birds, where they mature in this small sac off the gut, and the B in their name has stood for bursa ever since.
Q 16Developing T cells undergo positive selection in which part of the thymus?
The cortex
The cortex. Here each young T cell is tested on whether it can recognise the body's own identity tags at all; only then does it move inward to the medulla for the opposite test, of whether it reacts to them too strongly.
Q 17During which life stage does the thymus begin to atrophy and fill with fatty tissue?
Adolescence
Adolescence. The thymus does most of its work in childhood; from puberty it slowly shrinks and turns to fat, which is thought to be why the body makes fewer new T cells as it ages.
Q 18Where in the body is the thymus located?
Lower neck and upper chest
Lower neck and upper chest. The thymus sits just behind the breastbone, in front of the heart, and it is where T cells mature, which is how they came by the T in their name.
Q 19Which infection, spread in saliva and common in teenagers, typically brings swollen lymph nodes in the neck?
Mononucleosis
Mononucleosis. Saliva is how it earned the nickname 'the kissing disease', and the 'glands' behind its British name, glandular fever, are those same swollen lymph nodes.
Q 20Which part of the spleen synthesises antibodies and houses its lymphocytes?
The white pulp
The white pulp, named for looking paler than the tissue around it, wraps the spleen's small arteries like a lymph node built into the bloodstream. The red pulp around it does the filtering of worn-out blood cells.
Q 24The spleen breaks down haemoglobin from old red cells into which reusable building blocks?
Amino acids
Amino acids. They are sent off to help build brand-new red cells, and the iron at the heart of each haemoglobin molecule is saved and reused as well.
Q 25Roughly how many lymph nodes does the human body contain?
Several hundred
Several hundred. Textbooks cannot agree on the exact figure, with counts running from about 450 to about 800, but you can feel a few of them for yourself in the neck, armpit and groin when they swell.
Q 26What is the indentation on one side of a lymph node, which gives it its bean shape, called?
The hilum
The hilum. It is the node's only way out: lymph arrives through several vessels around the rim but leaves by this one notch, where the node's blood vessels also pass in and out.
Q 27Vessels that carry lymph into a lymph node are described by which adjective?
Afferent
Afferent. Several of these vessels feed each node around its outer curve, so lymph trickles in from many directions at once but is funnelled out again through just one.
Q 28In which part of a lymph node does the selection of B cells take place?
Germinal centre
Germinal centre. It forms only once an invader has been spotted: B cells multiply there at speed and shuffle their antibody genes, and the ones whose antibodies grip the invader best are the ones kept.
Q 29Lymphocytes enter lymph nodes through what specialised blood vessels in the paracortex?
High endothelial venules
High endothelial venules. The name describes their lining: the cells are tall and plump instead of flat, which lets lymphocytes squeeze straight out of the bloodstream and into the node.
Q 30Which gut organ has a colon-like lining that is heavily infiltrated with lymphocytes?
The appendix
The appendix. Its lining is crowded with lymphocytes that sample whatever the gut sends past, and when its narrow opening gets blocked, the reaction they set off can turn into appendicitis.