Interactive Blood Cell Model: Every Blood Cell in 3D, Its Job and Its Life
Turn a red cell, the five white cells and a platelet in 3D, watch them flow in their real numbers, follow each one from the bone marrow to the end of its life, then make the blood ill and see what changes.
Press ▶ to let the days run: red cells take weeks to respond, neutrophils hours.
What's in this blood
Lab notebook
Every blood test, donation, condition and measurement is written here with its day. Export a CSV, or turn the session into a PDF lab report.
| # | Day | What | Result |
|---|
Concept library
Click "New problem" to begin.
Click "Start quiz" for 5 questions on the blood cells, their jobs, their numbers, their life cycle and blood disorders.
1 Overview
The model has three views. Blood is an arteriole cut open with the cells flowing in their real numbers and a spun blood sample beside it. Cell shows one cell big, with its parts labeled. Life cycle plays one cell's whole life as a cycle (its Journey): the cell changes shape stage by stage, from a stem cell in the bone marrow, through the blood, to its end in a tissue or the spleen, and back to the marrow. Pick any of the seven cells at the bottom, pause, step with ⏮ ⏭ (or the arrow keys), or click a stage on the ring. Family tree shows where every blood cell comes from. On the right, About describes the selected cell, Blood count is the person's full blood count and Over time graphs it over days. Experiment has five practicals with a lab report; Quiz has practice questions and a 5-question quiz.
2 Looking at the cells
- Pick a cell in the Cells panel or the strip at the bottom of the Cell view, or click any cell in the vessel.
- In 3D, drag to turn the cell; hold Ctrl (⌘ on a Mac) and scroll, or pinch, to zoom. Cut the cell open (View panel) slices it to show the inside.
- Line up all cells to scale puts the seven side by side on a micrometer ruler; drag across a cell to measure it.
- The Look at chips show the cell as it looks in disease: a sickle cell, a small pale cell, a 6-lobed neutrophil, an activated platelet and more.
3 The blood view and the real ratio
For every white cell there are about 700 red cells and 35 platelets, so you may have to wait to see a white cell go by. Tick Show 20× more white cells to see more of them (the census strip says so while it is on). The spun tube shows plasma (about 55 %), the thin buffy coat of white cells and platelets (under 1 %) and the packed red cells (the hematocrit, about 45 %).
4 Conditions and the days
Choose a condition in the Condition panel: the blood is set to that disease's steady state, and every view changes with it. In Body, donate blood, catch an infection, move to altitude or take iron tablets, then press ▶ to run the days (1 day or 1 week per second) and watch Over time. 🧪 Blood test records a full blood count in the notebook.
5 Experiment mode and the lab report
Five labs: the hematocrit of three spun samples, the sizes of the blood cells, CBC detective with mystery patients, recovery after a blood donation, and living at altitude. Each shows its aim, what you need and a safety note; the method ticks off as you work and a conclusion question ends it. Then create a PDF lab report.
6 Quiz and units
The practice quiz covers identifying cells from a picture, their jobs, numbers and sizes, the composition of blood, the life cycle and blood counts in disease, each with a worked solution. SI | US switches hemoglobin between g/L and g/dL, the hematocrit between L/L and %, and counts between ×10⁹/L and per µL. Cell sizes stay in micrometers.
7 Keyboard
- 1–3 pick Blood, Cell or Life cycle; A, C, G pick About, Blood count or Over time; Space runs the days; T takes a blood test; L shows or hides labels; N starts again. Right-click a view to save it as an image.
Types of blood cells: an interactive 3D blood cell model
Blood looks like one red liquid, but it is a living tissue: a pale yellow fluid, plasma, carrying three kinds of cells. This free interactive blood cell model lets you pick each one up in 3D, see them to true scale, watch them flow in a vessel in their real numbers and follow their whole life, from a stem cell in the bone marrow to the macrophage that eats them. One model of the marrow drives every view, so when you choose anemia or leukemia the cells, the spun tube and the blood count all change together.
- Cells
- Red blood cell, neutrophil, lymphocyte, monocyte, eosinophil, basophil, platelet
- Views
- Flowing blood with a spun tube, one cell in 3D, the life-cycle tree, the blood count
- Conditions
- 13, from iron-deficiency anemia and sickle cell disease to leukemia, ITP and polycythemia
- Modes
- Simulate, Experiment (5 practicals with a PDF report) and Quiz
- Price
- Free, no account or download; works on Chromebooks, tablets and phones
The types of blood cells and their functions
| Cell | Size | Number per µL | Lives | Job |
|---|---|---|---|---|
| Red blood cell (erythrocyte) | 7.5–8 µm disc | 4–6 million | ~120 days | Carries oxygen on hemoglobin |
| Neutrophil | 12–15 µm | 1,800–7,700 | ~7 hours in blood | Eats bacteria; first to arrive |
| Lymphocyte | 7–10 µm | 1,000–4,800 | Weeks to decades | Antibodies (B), killing infected cells (T) |
| Monocyte | 15–20 µm | 200–800 | 1–3 days, then a macrophage | Becomes a macrophage that cleans up |
| Eosinophil | 12–17 µm | 50–450 | 8–12 hours in blood | Fights worms; allergy |
| Basophil | 10–14 µm | 0–200 | Hours to days | Releases histamine and heparin |
| Platelet | 2–3 µm fragment | 150,000–450,000 | 7–10 days | Plugs leaks and starts clotting |
The ratio is striking: in a healthy adult there are about 700 red cells and 35 platelets for every white cell. Red cells make up about 99 % of the cells in blood, and with about 25 trillion of them they are around 84 % of all the cells in the human body.
The composition of blood
Spin a tube of blood in a centrifuge and it separates into three layers. On top is plasma, about 55 % of the volume: 92 % water, 7 % proteins (albumin, globulins such as antibodies, and the clotting protein fibrinogen) and 1 % salts, glucose, hormones, urea and dissolved gases. Under it is a thin white buffy coat, under 1 %, made of white cells and platelets. At the bottom are the packed red cells, about 45 %: this fraction is the hematocrit. An adult has about 5 liters of blood, roughly 7 % of body weight.
The life cycle of blood cells (hematopoiesis)
Every blood cell starts as a hematopoietic stem cell in the red bone marrow of the pelvis, spine, ribs, sternum and the ends of the long bones. Its daughters split into two families. The myeloid line makes red cells, platelets, granulocytes and monocytes; the lymphoid line makes B cells, T cells (which finish maturing in the thymus) and NK cells. Growth factors steer the output: erythropoietin (EPO) from the kidneys raises red cell production when oxygen is low, thrombopoietin from the liver raises platelets, and G-CSF raises neutrophils in an infection. A red cell takes about a week to make, loses its nucleus, spends a day in the blood as a reticulocyte, works for about 120 days and is then eaten by macrophages in the spleen and liver, which recycle its iron and turn its heme into bilirubin. Your marrow replaces about 2.4 million red cells every second.
Blood disorders and the complete blood count
A complete blood count (CBC) measures the cells, and the pattern points to the cause. Anemia is a low hemoglobin: small pale cells (low MCV) suggest iron deficiency, large cells (high MCV) vitamin B12 or folate deficiency, and a high reticulocyte count means cells are being destroyed (as in sickle cell disease and malaria) rather than not made. Too many neutrophils suggest a bacterial infection, too many lymphocytes a virus, too many eosinophils worms or allergy. In leukemia immature blasts crowd the marrow, so red cells and platelets fall while the white count may soar; in aplastic anemia every line falls together. This is an educational model with average values: it is not medical advice, and real reference ranges differ between laboratories.
Experiments and course links
| Lab | What you find out | Course links |
|---|---|---|
| Spin the blood: hematocrit | What fraction of blood is cells, and who is anemic | GCSE 4.2.2.3; IGCSE 0610; NCERT 11 |
| How big is a blood cell? | Sizes in micrometers and which cell is largest | NGSS MS-LS1-1; GCSE microscopy |
| CBC detective | Diagnosing mystery patients from their counts | A&P; health science; IB C3.2 |
| After a blood donation | Reticulocytes, EPO and recovery time | NGSS HS-LS1-3; A-level homeostasis |
| Living at altitude | Why athletes train high | GCSE/IGCSE; A&P |
Who uses this blood cell model?
Middle and high school students learning the components of blood (NGSS, GCSE, IGCSE, IB, NCERT Class 11), first-year anatomy and physiology, nursing and health-science students meeting the blood count for the first time, and teachers who want a free, no-login model for a classroom screen, homework or a blood cell model project.
Frequently asked questions
What are the 3 types of blood cells and their functions?
Red blood cells (erythrocytes) carry oxygen from the lungs to the tissues on hemoglobin and help carry carbon dioxide back; there are about 4 to 6 million in every microliter of blood and each lives about 120 days. White blood cells (leukocytes) defend the body against infection; there are only 4,500 to 11,000 per microliter, in five kinds: neutrophils, lymphocytes, monocytes, eosinophils and basophils. Platelets (thrombocytes) are small fragments of megakaryocytes that plug damaged vessels and start a blood clot; there are 150,000 to 450,000 per microliter and each lasts 7 to 10 days. All three are made in the red bone marrow from the same stem cells.
What are the 5 types of white blood cells?
From most to least common: neutrophils (40–70 %, a 3- to 5-lobed nucleus, eat bacteria), lymphocytes (20–40 %, a large round nucleus; B cells make antibodies and T cells kill infected cells), monocytes (2–8 %, the largest, become macrophages in the tissues), eosinophils (1–4 %, a two-lobed nucleus and red-orange granules, fight worms and take part in allergy) and basophils (under 1 %, dark granules of histamine and heparin). The mnemonic Never Let Monkeys Eat Bananas gives the order. Neutrophils, eosinophils and basophils are granulocytes; lymphocytes and monocytes are agranulocytes.
Why do red blood cells have no nucleus and a biconcave shape?
A mature red blood cell pushes out its nucleus (and loses its mitochondria) before it enters the blood, which leaves more room for hemoglobin, about 270 million molecules per cell, and means the cell does not use up the oxygen it carries. The biconcave disc, about 7.8 micrometers across, 2.5 micrometers thick at the rim and under 1 micrometer at the center, gives about 40 % more surface area than a sphere of the same volume and keeps every part of the cell close to the surface, so oxygen diffuses in and out quickly. It also makes the cell flexible enough to fold through capillaries only 3 micrometers wide.
Explore related simulators
Stain a real blood smear and count the white cells under the lenses of the Virtual Microscope. Follow the blood these cells travel in through the Heart Simulator: Blood Flow & Cardiac Cycle, see red cells pick up oxygen in the lungs with the Respiratory System Simulator, and put red cells in salt and sugar solutions in the Osmosis Lab. Blood groups are crossed in the Interactive Punnett Square Calculator.
Sources: Hall & Hall, Guyton and Hall Textbook of Medical Physiology 14th edition, chapters 33–37; OpenStax Anatomy and Physiology 2e, chapter 18; OpenStax Biology 2e, section 40.2; Evans & Fung, Microvascular Research 4 (1972); Sender, Fuchs & Milo, PLOS Biology 14 (2016); Hoffbrand & Moss, Essential Haematology 8th edition; Kiss et al., JAMA 313 (2015). An educational model: not medical advice.
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