Biology and Anatomy, Step by Step
The body, the cell and the ward, drawn so you can walk through each one a step at a time, or press any part to see what it does. Every label leads to its dictionary entry.
The Human Body
11 diagramsOrgans and systems, and how they work: the heart, the brain, the senses, breathing, digestion and the kidney.
Human Anatomy · Structure
Human Heart
The parts of the human heart and what each does: the four chambers, the four valves, the septum, the wall and the great vessels that carry blood in and out.
Open the diagram18 partsPhysiology · Pathway
Blood Flow Through the Heart
The path blood takes through the heart, in order: from the venae cavae through the right side to the lungs, then back through the left side to the aorta.
Open the diagram11 stepsNeuroscience · Structure
Human Brain
The human brain from the side: the four lobes, the cerebellum, the brainstem and the cortex areas for movement, touch, speech, hearing and sight.
Open the diagram18 partsHuman Anatomy · Structure
Human Eye
The parts of the human eye and what each does: the cornea, iris, lens and ciliary body, the three coats, the retina with its fovea, and the optic nerve.
Open the diagram16 partsHuman Anatomy · Structure
Human Ear
The parts of the human ear and what each does: the auricle, ear canal, eardrum, ossicles, cochlea, semicircular canals and the nerve to the brain.
Open the diagram16 partsHuman Anatomy · Structure
Digestive System
The organs of the digestive system and what each does, from the mouth, stomach and intestines to the liver, gallbladder and pancreas.
Open the diagram17 partsHuman Anatomy · Structure
Respiratory System
The parts of the respiratory system and what each does, from the nose and trachea to the bronchi, the lobes of the lungs and alveoli.
Open the diagram20 partsHuman Anatomy · Structure
Skin
The layers of the skin and what each does: epidermis, dermis and hypodermis, with hair, glands, blood vessels, nerves and touch receptors.
Open the diagram19 partsNeuroscience · Structure
Neuron
The parts of a neuron and what they do: dendrites, cell body, axon hillock, axon, myelin sheath, nodes of Ranvier, axon terminals and the synapse.
Open the diagram15 partsPhysiology · Process
Nephron
How a nephron makes urine: filtration at the glomerulus, reabsorption along the tubule, the loop of Henle, and the hormones that set the final volume.
Open the diagram9 stepsNeuroscience · Process
Action Potential
How a neuron fires: from rest at −70 mV to threshold, sodium rushing in, potassium flowing out, the undershoot and back, the spike itself over in 1 to 2 ms.
Open the diagram9 steps
Cells and Molecules
9 diagramsInside the cell: its parts, how it divides, how DNA is copied and read, and the pathways that power it.
Cell Biology · Structure
Plant Cell
The parts of a plant cell and what each does: the cell wall, chloroplasts, the central vacuole, the nucleus, the ER and more.
Open the diagram15 partsCell Biology · Structure
Animal Cell
The parts of an animal cell and what each does: the nucleus, the endoplasmic reticulum, the Golgi apparatus, mitochondria, lysosomes and more.
Open the diagram14 partsMolecular Biology · Structure
DNA Structure
The structure of DNA: nucleotides, the sugar-phosphate backbone, base pairs and hydrogen bonds, antiparallel strands and the grooves.
Open the diagram14 partsBotany · Process
Photosynthesis
How a chloroplast turns light, water and carbon dioxide into sugar and oxygen: the light-dependent reactions and the Calvin cycle.
Open the diagram10 stepsCell Biology · Process
Mitosis
The stages of mitosis, from prophase to telophase and cytokinesis: how one cell's copied chromosomes are shared equally between two new cells.
Open the diagram8 stepsMolecular Biology · Process
Protein Synthesis
How a cell makes a protein: a gene is transcribed into mRNA in the nucleus, processed and exported, then translated by a ribosome.
Open the diagram10 stepsMolecular Biology · Process
DNA Replication
How a replication fork copies DNA: helicase opens the helix, primase lays primers, and DNA polymerase builds a leading and a lagging strand.
Open the diagram10 stepsBiochemistry · Pathway
Krebs Cycle
The Krebs cycle breaks the acetyl group of acetyl-CoA down to carbon dioxide and keeps its energy as NADH, FADH₂ and GTP, in eight steps.
Open the diagram10 stepsMolecular Biology · Process
PCR
How PCR copies one stretch of DNA: heat the strands apart, cool so primers bind, let Taq build new strands, and repeat until the copies number billions.
Open the diagram7 steps
Medicine and Nursing
4 diagramsThe diagrams of the ward and the exam: the ECG, clotting, lab values in shorthand and how infection spreads.
Physiology · Process
Cardiac Conduction System
How the heart's electrical impulse travels from the SA node to the Purkinje fibres, and the stage of the beat behind each ECG wave: P, QRS and T.
Open the diagram9 stepsPhysiology · Pathway
Coagulation Cascade
How the coagulation cascade turns fibrinogen into fibrin: the intrinsic, extrinsic and common pathways, the PT and aPTT, and the drugs that act on it.
Open the diagram10 stepsMedicine · Structure
Lab Values Fishbone
How to read the lab values fishbone: the BMP (Chem 7) and CBC shorthand written on clinical notes, with each value's normal adult range.
Open the diagram14 partsEpidemiology · Process
Chain of Infection
The six links of the chain of infection, from infectious agent to susceptible host, and how hand hygiene, PPE, cleaning and vaccination break each one.
Open the diagram8 steps