Explore the Blood Flow & Circulatory System Simulator
Follow blood from the heart through arteries, arterioles, capillaries and veins, and see how strongly flow depends on vessel radius.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
Illustration. Open the tool for the real thing.
See it in action
The Blood Flow & Circulatory System Simulator with sample data entered and the result showing.
What is the Blood Flow & Circulatory System Simulator?
Follow blood from the heart through arteries, arterioles, capillaries and veins, and see how strongly flow depends on vessel radius. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
This r⁴ relationship is why blood-pressure medications that dilate arterioles work so powerfully, and why cholesterol plaques that narrow arteries are so dangerous.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Poiseuille's law: flow is proportional to the fourth power of the vessel radius.
Arterioles are the body's main resistance vessels because their radius changes the most.
Blood pressure falls steadily along the vascular tree, dropping fastest across the arterioles.
Halve the arteriole radius and predict the drop in flow before checking.
Raise blood viscosity and compare it with the effect of the same percentage change in radius.
Read the pressure-along-the-tree graph and find where pressure falls fastest.
Used for
Pick one to see how it fits.
Biology learners
Biology students and teachers who want to explore living systems, populations and genetics interactively and safely.
Try it freeTeachers
For teachers: project the Blood Flow & Circulatory System Simulator on the board, let students predict the result, then run it together and test this: Raise blood viscosity and compare it with the effect of the same percentage change in radius. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
Why does a small change in blood vessel radius change flow so much?
Because flow depends on radius to the fourth power, so halving the radius cuts flow to about one sixteenth.
Where does blood pressure fall the most in the circulatory system?
Across the arterioles, which is exactly why the body uses them to control blood pressure and how much blood organs receive.
Is the Blood Flow & Circulatory System Simulator free to use?
Yes. The Blood Flow & Circulatory System Simulator is free, needs no signup or download and runs in your web browser. It is part of the Biology group of AZRS simulations.
Does the Blood Flow & Circulatory System Simulator work on a phone or tablet?
Yes. The Blood Flow & Circulatory System Simulator takes touch input as well as mouse input, so you can use its 4 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Blood Flow & Circulatory System Simulator?
1. In the Blood Flow & Circulatory System Simulator, use the controls to change Arteriole radius, Blood viscosity, Driving pressure (heart), Heart rate. The simulation reacts instantly. 2. In the Blood Flow & Circulatory System Simulator, press "Check flow drop", "Check compensation" to start, reset or change what is happening. 3. Start with this experiment: Halve the arteriole radius and predict the drop in flow before checking. Drag any glowing handle, object or slider with your mouse or finger and the Blood Flow & Circulatory System Simulator responds in real time. 4. Change one setting at a time and watch which readout moves, then compare it with this idea: Poiseuille's law: flow is proportional to the fourth power of the vessel radius.
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Try the Blood Flow & Circulatory System Simulator now
Follow blood from the heart through arteries, arterioles, capillaries and veins, and see. Free to use.
Try it free