Circulatory System Crossword

Print a criss-cross vocabulary crossword on the circulatory system: the heart, the vessels, the blood and how it all flows.

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Circulatory System Crossword

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Answer key: Circulatory System Crossword

1FO2PUL3SEUT4ORG5AN6HERET7WATERAHERO8R9CIRCUITSHYBCY10VEOTAAPH11BLOODSTREAMV12VEIN

Across 2 PULSE · 4 ORGAN · 7 WATER · 9 CIRCUIT · 11 BLOODSTREAM · 12 VEIN

Down 1 FOUR · 3 STETHOSCOPE · 5 ARTERY · 6 HEARTBEAT · 8 RHYTHM · 10 VALVE

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The Heart 27

  • Aortic Word for the one-way gate between the left lower chamber and the largest outgoing vessel
  • Apex Lowest point of the heart, aimed toward the left
  • Atrium Chamber of the heart that pumps blood down into the chamber below it
  • Cardiac Word that means of the heart, as in ___ muscle
  • Chest Part of the body where the heart sits, near the lungs
  • Contract To squeeze, as heart muscle does when an electric message reaches it
  • Coronary Left ___ and right ___: the two supply lines of the heart's own muscle
  • Cusp One of the flaps that swing apart and shut in time with the pumping
  • Endocardium Thin inner lining of the heart chambers
  • Fist A hand squeezed shut, roughly as big as the heart
  • Four Number of hollow chambers in the human heart
  • Involuntary Word for muscle, like the heart's, that works without your deciding
  • Mediastinum Region that holds the heart, level with the fifth to eighth vertebrae of the upper back
  • Mitral Named for a bishop's headdress: the two-flap gate on the left side of the heart
  • Myocardium The heart's muscle layer, between the inner lining and the outer sac
  • Node Sinoatrial ___, or SA ___: the starting point of each beat
  • Organ The heart is one, at the center of the circulatory system
  • Pacemaker Word for the cells in the right upper chamber where each beat begins
  • Pericardium Sac that surrounds the heart and holds it in place
  • Pulmonary Word shared by one heart gate, one outgoing vessel and the vessels back from the lungs
  • Relax What the lower chambers do after pumping, before the next beat starts
  • Septum Partition inside the heart, between its two halves
  • Strings Heart ___: everyday name for the cords that anchor two of the one-way gates
  • Three Number of tissue layers that make up the heart
  • Tricuspid The one-way gate between the right upper and lower chambers
  • Valve The lub and the dub are the sounds of these shutting
  • Ventricle Chamber of the heart; the left one pushes blood to the whole body

Blood Vessels 25

  • Aorta Large vessel that carries blood out of the heart to the rest of the body
  • Arteriole Small vessel with muscular walls that leads on to the smallest vessels of all
  • Artery Kind of vessel you press at the inner wrist to feel your beats
  • Branch To split into smaller and smaller vessels, as a tree limb does
  • Capillary Tiny vessel where blood and body tissue trade oxygen and wastes
  • Carotid Vessel on each side of the neck where a beat can be felt
  • Endothelium Inner coat of a vessel, one cell deep, in touch with the passing blood
  • Femoral Word for the large outgoing vessel of the thigh
  • Five Number of kinds of blood vessel in the body
  • Jugular Internal or external: neck vessel on the return route to the heart
  • Lumen The hollow where the blood actually runs; plural lumina
  • Narrowing What vasoconstriction means for a blood vessel
  • Network Web of blood vessels that reaches all areas of the body
  • Portal Hepatic ___: vessel whose blood reaches the liver from the pancreas and the gallbladder
  • Radial Word for the large forearm vessel that runs to the wrist
  • Renal Word for the vessel that supplies blood to a kidney
  • Saphenous Great ___: leg vessel that returns blood from the foot to the top of the thigh
  • Smooth Kind of muscle that tightens or loosens to change a vessel's width
  • Subclavian Word for the vessels that take blood from the arch above the heart to the arms
  • Tunic Name for each of the 3 layers of a vessel wall, like the old word for a garment
  • Umbilical ___ cord: lifeline of an unborn baby, normally holding 3 blood vessels
  • Vasodilation The loosening of muscle in vessel walls, which makes more room for blood
  • Vein Kind of vessel with small one-way flaps inside to stop blood sliding back
  • Vena cava Its two parts, superior and inferior, empty into the right upper chamber
  • Venule Very small vessel that collects blood on its way back toward the heart

The Blood 29

  • Antibody Protein built of chains that form a Y
  • Antigen Marker on a red cell, such as A or B, that a blood group is named for
  • Bloodstream The flow of blood around the body, taken as a whole
  • Bright ___ red: the color of blood when it is rich in oxygen
  • Carbon dioxide Gas with the formula CO2, unloaded by the blood in the lungs
  • Clot Plug that forms when blood changes from a liquid to a gel
  • Disk Biconcave ___: the flexible, dented shape of a mature red blood cell
  • Donor The giver at a blood drive
  • Erythrocyte Formal name for a red blood cell, from the Greek erythros, red
  • Fibrin Fibrous protein involved when blood sets into a gel
  • Hematocrit Red cells as a share of the whole, given as a percent
  • Hemoglobin Red cells can be viewed as sacks of this
  • Hormone Chemical made in a gland and released into the blood to control other body functions
  • Iron Metal in the oxygen-binding molecule of red cells
  • Leukocyte One of the cells that guard the body against foreign invaders
  • Lymph Fluid of a second vessel system that works beside the blood
  • Marrow Bone filling that turns out about 500 billion new blood cells a day
  • Nucleus Cell part that a mature human red blood cell lacks
  • Phagocyte Cell whose Greek name means one that eats
  • Plasma Part of blood left when the cells are taken away
  • Platelet Tiny part of blood that reacts to bleeding by clumping together
  • Rhesus Monkey whose name gives the Rh in Rh factor
  • Serum The liquid of blood with all cells and all gel-forming factors removed
  • Seven Percent of a human's body weight that is blood
  • Spleen Blood filter that removes old red cells and holds a reserve of blood
  • Transfusion What a hospital does with a stored bag of blood for a patient
  • Type A, B, AB or O
  • Universal People with O, Rh D-negative blood are often called this kind of giver
  • Water The liquid part of blood is 92% this by volume

How Blood Circulates 25

  • Amphibian Animal such as a frog, whose heart has 3 chambers
  • Circuit Round trip; blood makes one through the lungs and one through the body
  • Closed Kind of circulatory system in which blood never leaves the vessels
  • Cycle Everything the heart does from the start of one beat to the start of the next
  • Deoxygenated Word for the darker blood that comes back from the body to the right side of the heart
  • Diastole Part of each beat when the chambers of the heart are refilling
  • Double Kind of circulatory system, like ours, with one path to the lungs and another to the body
  • Exchange Trade of substances between blood and tissue across the thinnest vessel walls
  • Faster How your heart beats when you exercise
  • Gills Where a fish's blood picks up oxygen
  • Heartbeat It makes a lub-DUB sound
  • Hemolymph Body fluid of insects, spiders and other arthropods, comparable to blood
  • Loop A fish's blood makes a single one: heart, breathing surfaces, body and back
  • Nutrients Along with oxygen, what your blood carries around the body
  • Open Kind of circulatory system of many invertebrates, with fluid returning via the body cavity
  • Output Volume of blood that one lower chamber pumps in a minute: the heart's ___
  • Oxygenated Freshly supplied with O2 in the lungs
  • Pressure Blood ___: the push of blood against vessel walls as the heart pumps
  • Pulse Tapping felt at the inner wrist, just below the thumb
  • Rate Heart ___: the number of beats in one minute
  • Rhythm Steady pattern of beats, kept by the heart's electrical system
  • Signal With each beat an electric one travels from the top of the heart to the bottom
  • Systemic Word for the round trip that takes blood from the left side of the heart to the body
  • Systole Part of each beat when chambers of the heart squeeze after refilling
  • Whale Sea mammal with the largest heart known: 180 kg in one blue specimen

Tools and Discoveries 21

  • Auscultation Medical word for listening to the sounds inside the body
  • Cardiology Field of the heart specialist
  • Cuff Armband that is pumped full of air to take a blood reading
  • Diastolic Word for the lower number of an arm reading, taken between beats
  • ECG Short name for a recording of the electrical activity of the heart
  • Electrode Small sensor placed on the skin to pick up the heart's electrical activity
  • Fingers Index and middle ___: what to rest on the inner wrist to feel the beats
  • Flute Wooden instrument a French doctor carved, a skill that led to his 1816 listening tube
  • Galen Ancient physician whose view that the liver makes the blood was challenged in 1628
  • Harvey William ___, English physician whose book of 1628 described the circulation of the blood
  • Laennec René ___, French doctor who invented the listening tube in 1816
  • Landsteiner Karl ___, who discovered the ABO blood groups in 1901
  • Malpighi Marcello ___, who in 1661 described the tiny links between outgoing and returning vessels
  • Mercury Liquid metal in mmHg, the unit on a blood monitor
  • Microscope Tool that the Italian anatomist who described the tiniest vessels worked with
  • Nobel Prize given in 1930 for the discovery of the ABO blood groups
  • Oximeter Fingertip clip that shines light through the skin to read blood oxygen
  • Padua Italian university that made the author of the 1628 circulation book a doctor in 1602
  • Stethoscope You can hear the lub-DUB through one
  • Systolic Word for the higher number of an arm reading, taken as the lower chambers pump
  • Thirty Seconds to count beats before multiplying by 2

How this list was compiled: Clues written for this site for grades 5 to 8 science, in five sets: the heart, blood vessels, the blood, how blood circulates, and tools and discoveries. Facts were checked against How the Heart Works, pages of the National Heart, Lung, and Blood Institute (nhlbi.nih.gov), and English Wikipedia (CC BY-SA 4.0), in October 2026. Heart and Blood are clue words, never answers. Anatomy only: a study aid, not health advice. Licence: own work

How it works

This circulatory system crossword prints on Letter or A4 with its answer key. The first puzzle has 12 easy words, among them Artery, Vein, Valve, Pulse and Heartbeat. "The lub and the dub are the sounds of these shutting" is Valve.

Read the full guide

Five sets after the easy one

The Heart has Atrium, Ventricle, Septum and Pacemaker. Blood Vessels has Capillary, Aorta, Carotid and Jugular. The Blood has Plasma, Platelet, Hemoglobin and Marrow. How Blood Circulates has Systole, Diastole, Pressure and Circuit. Tools and Discoveries has Stethoscope, Cuff, Mercury and Microscope.

Fish, amphibian and whale hearts

How Blood Circulates looks beyond people: Gills and Loop for a fish, whose heart has two chambers, Amphibian for a heart with three, and Whale for the largest heart known, 180 kg in one blue whale.

  • Print Tools and Discoveries on the day the class counts a pulse: Fingers and Thirty are answers they have just acted out.

Questions and answers

What grade is the circulatory system crossword for?

Easy Circulatory System Words suits grades 4 to 6, with answers such as Artery, Vein, Fist and Chest. The five themed sets use unit vocabulary for grades 6 to 9, such as Myocardium and Hematocrit. These bands are our judgment, not a published standard.

Can I save the circulatory system crossword as a PDF?

Yes. Press Print and choose Save as PDF in the print window. The puzzle and its answer key are saved together, and the key is the last sheet. It is free, with no sign-up.

What are the three main parts of the circulatory system?

The heart, the blood vessels and the blood. The heart pumps; arteries take blood away from it, veins bring blood back, and capillaries link the smallest arteries to the smallest veins.

How many chambers does the heart have?

Four: two upper chambers called atria and two lower chambers called ventricles. A wall called the septum divides the right side from the left. Atrium, Ventricle, Septum and Four are all answers.

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