Biology · Anatomy
Human Body
Build body systems and bones, open a four-chamber heart, explore muscle movement and sections, breathe with a 3D chest and alveolus, follow a bite through the gut, fire a neuron, trace brain pathways, and slice a CT/MRI volume.
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The course
19 worlds · 134 lessons
World 1 · Cells & Tissues
FREEThe building blocks of the body- 01What anatomy studiesStructure and function · 6 min
- 02The cellThe smallest unit of life · 6 min
- 03Inside the cellOrganelles and their jobs · 7 min
- 04Energy in the cellFuel + oxygen → energy · 6 min
- 05From cells to tissuesCells working together · 6 min
- 06The four tissue typesEpithelial, connective, muscle, nervous · 8 min
- 07Organs and systemsTissues build organs · 6 min
- 08Staying in balanceHomeostasis · 7 min
World 2 · Skeletal System
FREEBones, joints, and the body’s frame- 01The skeletonThe body’s framework · 7 min
- 02Bone as living tissueStructure, growth, and minerals · 7 min
- 03The axial skeletonSkull, spine, and rib cage · 7 min
- 04The appendicular skeletonArms, legs, and girdles · 7 min
- 05JointsWhere bones meet · 7 min
- 06Cartilage and ligamentsThe skeleton’s connective support · 6 min
- 07Growth and repairHow bone renews itself · 7 min
World 3 · Muscular System
PROHow the body creates movement- 01Three kinds of muscleSkeletal, smooth, cardiac · 7 minPRO
- 02Inside a skeletal muscleFibers and contraction · 7 minPRO
- 03How muscles move bonesPulling in pairs · 7 minPRO
- 04Muscle energy and fatigueWhy movement makes you breathe · 7 minPRO
- 05Posture and core musclesHolding the body up · 6 minPRO
- 06Muscle and the whole bodyA system that depends on the rest · 6 minPRO
World 4 · Cardiovascular System
PROThe heart, vessels, and blood- 01The heartA four-chambered double pump · 7 minPRO
- 02The cardiac cycleOne heartbeat, step by step · 6 minPRO
- 03Blood vesselsThe delivery network · 7 minPRO
- 04Lab: build the circulatory systemPlace the organs, then run · 8 minPRO
- 05BloodWhat it’s made of · 7 minPRO
- 06Pulse and blood pressureReading the pump · 7 minPRO
World 5 · Respiratory System
PROBreathing and gas exchange- 01The airwayFrom nose to lungs · 6 minPRO
- 02The lungs and alveoliWhere air meets blood · 7 minPRO
- 03The mechanics of breathingMuscles that move air · 7 minPRO
- 04Gas exchange and transportOxygen in, carbon dioxide out · 6 minPRO
- 05Controlling your breathAutomatic, with an override · 6 minPRO
- 06Lab: build the respiratory systemTrachea and both lungs · 8 minPRO
World 6 · Digestive System
PROTurning food into fuel- 01The digestive systemOne long processing line · 6 minPRO
- 02Mouth to stomachThe first steps · 6 minPRO
- 03The small intestineWhere absorption happens · 7 minPRO
- 04The liver, pancreas, and gallbladderThe accessory organs · 7 minPRO
- 05The large intestineReclaiming water · 6 minPRO
- 06Nutrients and metabolismWhat absorbed food becomes · 7 minPRO
- 07Lab: build the digestive systemFollow the food · 8 minPRO
World 7 · Urinary System
PROFiltering the blood, balancing fluids
World 8 · Nervous System
PROThe body’s fast control network- 01The nervous systemThe body’s wiring · 6 minPRO
- 02NeuronsCells built to signal · 7 minPRO
- 03SynapsesHow one neuron talks to the next · 6 minPRO
- 04The brainThe control centre · 7 minPRO
- 05The spinal cord and reflexesFaster than thought · 7 minPRO
- 06The autonomic nervous systemFight, flight, and rest · 7 minPRO
- 07Lab: build the nervous systemBrain, cord, and nerves · 8 minPRO
World 9 · Endocrine System
PROChemical messengers and glands- 01Hormones and glandsChemical messengers · 6 minPRO
- 02The pituitary glandThe "master gland" · 7 minPRO
- 03The thyroidSetting the body’s pace · 6 minPRO
- 04Adrenal glands and the pancreasStress and blood sugar · 7 minPRO
- 05Hormone feedback loopsSelf-correcting chemistry · 6 minPRO
- 06Two ways to communicateNervous vs endocrine · 6 minPRO
World 10 · Immune & Lymphatic System
PRODefence and fluid balance- 01The lymphatic systemA second circulatory network · 7 minPRO
- 02Innate immunityThe body’s first responders · 6 minPRO
- 03Adaptive immunityA targeted, learning defence · 7 minPRO
- 04Inflammation and feverDefence you can feel · 6 minPRO
- 05Immune memoryWhy past exposure matters · 6 minPRO
- 06Fluid balance and the whole bodyThe lymphatic system’s quiet role · 6 minPRO
World 11 · Integumentary System & Senses
PROSkin, and windows to the world- 01The skinThe body’s largest organ · 7 minPRO
- 02Hair, nails, and glandsSkin’s add-ons · 6 minPRO
- 03Regulating temperatureSkin and homeostasis · 6 minPRO
- 04SightThe eye · 7 minPRO
- 05Hearing and balanceThe ear · 7 minPRO
- 06Taste and smellThe chemical senses · 6 minPRO
- 07Touch and painSensing through the skin · 6 minPRO
World 12 · Reproductive System
PROGrowth, hormones, and new life- 01The reproductive systemA system with a different job · 6 minPRO
- 02The male reproductive systemOrgans and hormones · 7 minPRO
- 03The female reproductive systemOrgans and hormones · 7 minPRO
- 04The menstrual cycleA monthly hormonal rhythm · 7 minPRO
- 05PubertyHormones driving change · 6 minPRO
- 06Fertilization and early developmentFrom two cells to many · 7 minPRO
- 07One connected bodyEvery system, working together · 7 minPRO
World 13 · Structure, sections & movement
PROBuild bones, open the heart and inspect musculoskeletal sections- 01Assemble the key bonesPlace all 16 selected skeletal pieces in their correct locations. · 6 minPRO
- 02Open four heart chambersOpen the anterior section to at least 80%, select each of the four chambers and record it. · 6 minPRO
- 03Trace the double circulationTrace all 15 blood stations in order; record the completed route and each of the four valve phases. · 6 minPRO
- 04An antagonistic muscle pairRecord elbow poses at 20° and 120° flexion and compare both attachment distances. · 6 minPRO
- 05Read an upper-arm sectionAt a section height between 40% and 60%, select and record biceps, triceps and humerus. · 6 minPRO
- 06Inside a long-bone shaftAt a section height between 40% and 60%, record cortical bone and the medullary cavity. · 6 minPRO
World 14 · Lungs & breathing
PRODiaphragm, pressure and gas exchange in a 3D chest- 01Boyle’s law in the chestExpand the chest with the airway shut · 8 minPRO
- 02Inhale and exhaleSmall pressure differences move the tidal volume · 8 minPRO
- 03When the pleural seal breaksAn open pneumothorax on one side · 8 minPRO
- 04Gas exchange in an alveolusDiffusion down partial-pressure gradients · 8 minPRO
World 15 · Digestive journey
PROFollow a bite from mouth to intestine; switch enzymes on and off- 01Where protein digestion startsPepsin, acid and a back-up in the small intestine · 9 minPRO
- 02Fat, lipase and bileSwitch off lipase or bile and follow the fat · 9 minPRO
- 03Why amylase stops in the stomachpH, denaturing and a second amylase · 9 minPRO
- 04Villi and surface areaFolds, villi and microvilli multiply the absorbing surface · 9 minPRO
World 16 · Neurons & action potential
PROIon channels, the travelling spike, myelin and the synapse- 01Threshold: all or noneFind the smallest stimulus that fires the axon · 10 minPRO
- 02The refractory periodTwo pulses: when can the axon fire again? · 10 minPRO
- 03Myelin and saltatory conductionCompare conduction speed with and without myelin · 10 minPRO
- 04Synapses: summation and TTXMake the postsynaptic cell fire, then block it · 10 minPRO
World 17 · Neuroanatomy
PROBrain regions, cranial nerves, the visual pathway and the long tracts- 01Brain regions and their jobsFind the part of the brain behind each function · 12 minPRO
- 02Cranial nervesExamine three patients and find the damaged nerve · 12 minPRO
- 03The visual pathwayPlace a lesion and see what part of the visual field is lost · 12 minPRO
- 04Long tracts and where they crossLesions in the brain and spinal cord · 12 minPRO
World 18 · Medical imaging
PROSlice a CT volume, set the window, weight an MRI and rebuild a CT slice from projections- 01A body made of voxelsSlice a 3D volume in three planes to find two findings · 10 minPRO
- 02CT numbers and the windowChoose window settings that make each tissue readable · 10 minPRO
- 03MRI contrast: T1 and T2Set TR and TE to make fluid dark, then bright · 10 minPRO
- 04How CT builds a sliceRebuild an axial slice from X-ray projections · 10 minPRO
World 19 · Practice Exams
PRO30 themed exams across every body system- 01Cells & Tissues BasicsThe building blocks of life · 8 minPRO
- 02Skeleton & MusclesFrame and movement · 8 minPRO
- 03The Heart & CirculationA double pump and its vessels · 8 minPRO
- 04Respiratory SystemBreathing and gas exchange · 8 minPRO
- 05Blood & ImmunityWhat's in blood, and how it defends you · 7 minPRO
- 06Nervous System BasicsThe body’s wiring · 7 minPRO
- 07The Brain & Spinal CordControl centre and main cable · 7 minPRO
- 08Reflexes & ReactionsFaster than thought · 6 minPRO
- 09The Senses OverviewWindows to the world · 6 minPRO
- 10Sight: The EyeHow you see · 6 minPRO
- 11Hearing & Balance: The EarSound and equilibrium · 6 minPRO
- 12Touch, Taste & SmellThe skin and chemical senses · 6 minPRO
- 13Digestive TractBreaking food down · 7 minPRO
- 14The Liver & Accessory OrgansThe chemical factory · 6 minPRO
- 15Kidneys & Urinary SystemFiltering the blood · 6 minPRO
- 16Endocrine GlandsChemical messengers · 6 minPRO
- 17Skin & the Integumentary SystemThe body's largest organ · 6 minPRO
- 18Cell Biology Deep DiveInside the cell · 7 minPRO
- 19Tissues in DepthThe four tissue types · 6 minPRO
- 20The Skeleton in DepthBone, structure, and support · 6 minPRO
- 21Joints & MovementWhere bones meet · 6 minPRO
- 22Muscles in DepthHow muscles create motion · 7 minPRO
- 23Reproductive SystemProducing offspring · 6 minPRO
- 24The Lymphatic SystemDraining fluid, defending the body · 6 minPRO
- 25Homeostasis & FeedbackStaying in balance · 6 minPRO
- 26Growth, Development & AgingThe body over a lifetime · 6 minPRO
- 27Nutrition & MetabolismFuel for the body · 6 minPRO
- 28Blood Vessels & Blood PressureArteries, veins, and pressure · 6 minPRO
- 29Anatomical Terms & Body PlanesThe language of position · 7 minPRO
- 30Whole-Body Mixed ReviewEverything, all at once · 9 minPRO
Read first
All guides →Guides for Human Body
Exam prepGeneticsAP and IB Biology: Cells and Genetics Study GuidePlan your revision of cell structure and Mendelian genetics for AP and IB Biology, with free interactive lessons, common pitfalls and a simple weekly study plan.
ExplainerHuman BodyHow the Human Body Is Organized: Cells, Tissues, BonesSee how cells build tissues, tissues build organs, and how the skeleton works as a living frame of bones, joints, cartilage and ligaments. With a live 3D lab.
ExplainerGeneticsPunnett Squares Explained: Mendel’s Rules of InheritanceLearn alleles, dominant and recessive traits, genotype versus phenotype and how to fill a Punnett square, then breed virtual creatures in a live 3D lab.