50 free Lymphatic System trivia questions with answers — science & nature quiz, new questions added Aug 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 50 questions with answers and explanations. Play the quiz
Q 01The lymphatic system is considered part of which other body system?
Immune
It works alongside the circulatory system, returning fluid to the blood while filtering out bacteria and damaged cells.
Q 02Unlike the closed circulatory system, the lymphatic system is described as what kind of system?
Open
Lymph starts as fluid that leaks out of blood capillaries into the tissues and is only later collected by blind-ended lymph vessels.
Q 03Lymph originates from which fluid that leaks out of blood into the tissues?
Interstitial
That fluid delivers nutrients to cells and collects waste, bacteria and damaged cells before draining into the lymph vessels.
Q 04Roughly how many litres of blood does the circulatory system filter through capillaries daily?
20
About 17 litres are reabsorbed straight back into the blood vessels, and the lymphatic system returns the remaining 3.
Q 05About how many litres of fluid a day does the lymphatic system return to the blood?
3
It is the leftover after most filtered plasma is reabsorbed directly, so the lymphatics act as an accessory return route.
Q 06Lymph is described as very similar to which component of blood?
Plasma
Like plasma it carries waste products, cellular debris, bacteria and proteins; its cells are mostly lymphocytes.
Q 07Where in the body are lymphocytes initially generated?
The bone marrow
B cells mature there too, while T cell precursors leave for the thymus to finish their training.
Q 08Mature naive lymphocytes are maintained and activated in which class of lymphoid organ?
Secondary
The lymph nodes and spleen are the classic examples; activation there leads to clonal selection and affinity maturation.
Q 09What does the acronym MALT stand for?
Mucosa-associated lymphoid tissue
It is the loosely organised lymphoid tissue found in mucosal linings such as the gut, tonsils and adenoids.
Q 10The large left lymphatic duct draining most of the body is known by what name?
Thoracic
The much smaller right lymphatic duct drains only the right upper side of the body.
Q 11The lymph ducts empty into which veins to return lymph to the bloodstream?
Subclavian
Those veins sit just under the collarbones, which is why the ducts finish their journey at the base of the neck.
Q 12With no central pump, what mainly moves lymph through the human body?
Muscle contractions
Some vertebrates, unlike humans, have a dedicated lymph heart that pumps lymph into the veins.
Q 13In which century was the lymphatic system first described as a system?
17th
Olaus Rudbeck and Thomas Bartholin worked independently, and their near-simultaneous claims led to a bitter priority dispute.
Q 21Which part of the spleen synthesises antibodies and houses its lymphocytes?
The white pulp
The other pulp, the red one, is where macrophages clear aged red blood cells and pathogens.
Q 22A 2009 mouse study found the spleen holds what fraction of the body's monocytes in reserve?
Half
Those reserve monocytes move to injured tissue such as the heart and become dendritic cells and macrophages.
Q 23Until which month of prenatal development does the human spleen make red blood cells?
Fifth
After birth the bone marrow takes over blood cell production entirely.
Q 14Which two organs make up the primary lymphoid organs where lymphocytes are produced?
Thymus and bone marrow
Secondary lymphoid organs such as the lymph nodes and spleen are where mature lymphocytes later meet their antigens.
Q 15Birds have an extra primary lymphoid organ that mammals lack. What is it called?
Bursa of Fabricius
It sits near the cloaca and is where B cells were first identified; the 'B' in B cell traces to this organ.
Q 16Developing T cells undergo positive selection in which part of the thymus?
The cortex
Only T cells able to recognise self-MHC molecules survive; those that bind too weakly die off before reaching the medulla.
Q 17Roughly what share of developing T cells survive both selection tests and reach maturity?
Less than 5%
Positive selection keeps cells that recognise self-MHC; negative selection removes those that bind self-antigens too strongly.
Q 18During which life stage does the thymus begin to atrophy and fill with fatty tissue?
Adolescence
Some T cell production continues throughout adulthood, but the gland's most active years are the neonatal and pre-adolescent periods.
Q 19Where in the body is the thymus located?
Lower neck and upper chest
Its lobules are divided by septa and built from epithelium, which is unusual for a lymphoid organ.
Q 20What does the absence of the thymus result in?
Severe immunodeficiency
Without it, T cells never become immunocompetent, leaving the body highly susceptible to infection.
Q 24What does the spleen do during acute blood loss?
Contracts, releasing stored red cells
It can store up to a quarter of the body's lymphocytes too, ready for an emergency.
Q 25The spleen breaks down haemoglobin from old red cells into what reusable building blocks?
800
The spleen recycles some erythrocyte components and discards others.
Q 26Roughly how many lymph nodes are in the human body?
About 800
Around 300 of them are packed into the head and neck alone.
Q 27What is the depression on a lymph node's surface, where the efferent vessel exits, called?
The hilum
It is what makes an otherwise spherical lymph node look bean-shaped; the node's arteries and veins pass through it too.
Q 28Vessels that bring lymph INTO a lymph node are described by which adjective?
Afferent
Several of them feed each node, but only a single efferent vessel carries the filtered lymph out again.
Q 29In which part of a lymph node does the selection of B cells take place?
Germinal centre
Lymph follicles swell dramatically when they encounter a foreign antigen.
Q 30Lymphocytes enter lymph nodes through what specialised blood vessels in the paracortex?
High endothelial venules
The paracortex surrounds the medulla and holds a mix of immature and mature T cells.