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Human Physiology: an interactive course on the body

Published 8 Nov 20265 min read

Human Physiology is an interactive human physiology course about how the body's systems keep you alive. Its 25 short sections cover cells, tissues and organs, the heart and cardiac output, arteries, veins and capillaries, blood, breathing and gas exchange, neurons and reflexes, the brain, digestion and enzymes, defending the body and vaccination, and homeostasis and blood glucose.

It opens with the double circulation loop and a heart-rate slider that updates the cardiac output live, and finishes by linking every system together during a run.

What the course covers

Sections	Topic	What you do
1 to 5	Cells to organs, the heart and cardiac output	Label the heart, then work out cardiac output
6 to 9	Blood vessels and what blood is made of	Sort features into artery, vein or capillary, then match the parts of blood
10 to 12	Breathing and gas exchange in the alveoli	Pick what each part does when breathing in and out
13 to 15	Neurons, reflexes and the brain	Put the steps of a reflex arc in order
16 to 18	Digestion and digestive enzymes	Match enzymes to their food, products and where they are made
19 to 21	Defending the body and vaccination	Sort defences into barriers, phagocytes and lymphocytes
22 to 24	Homeostasis and blood glucose	Read a glucose level, then pick the hormone and what the liver does
25	Systems working together	Link the systems during a run

Transport

The heart is a four-chambered pump: the atria take blood in and the ventricles pump it out, to the lungs on the right and the body on the left. Arteries carry blood away at high pressure, veins bring it back with valves to stop backflow, and thin capillaries let substances pass to and from cells. Our heart guide labels every part.

\text{cardiac output}=\text{stroke volume}\times\text{heart rate}

Gas exchange, nerves and digestion

In the alveoli, oxygen diffuses into the blood and carbon dioxide out. Neurons carry electrical impulses, and reflexes skip the conscious brain for speed. Digestion uses enzymes to break big food molecules into small ones the blood can absorb.

Defence and control

Skin and mucus keep most pathogens out; white blood cells engulf them or make antibodies, and vaccination trains the immune system in advance. Homeostasis keeps conditions steady, such as blood glucose, controlled by insulin and glucagon from the pancreas.

Try a question from the course

Cardiac output is how much blood one ventricle pumps each minute. If each beat pushes out a stroke volume of 70 ml and the heart beats 70 times a minute, the cardiac output is 70 × 70 = 4,900 ml, about 4.9 litres per minute.

Now work out a new cardiac output, then press Mark to check your answer in the course.

Press Mark to have your answer marked in the Human Physiology course.

Who this course is for

GCSE biology students revising organisation, circulation, gas exchange, the nervous system, disease and homeostasis.
Students heading for A-level biology, sport science, nursing or medicine who want the systems clear in their heads.
Anyone who wants to know what happens in their body when they exercise, eat or fight off a cold.

What you need to know first

The course page suggests Cell Biology first: diffusion, osmosis, enzymes and specialised cells come up throughout. The calculations are short multiplications and readings off a scale.

How long it takes

There are 25 sections and most take a few minutes. Learners without a plan can open two sections of a course a day, in order, so the whole course takes 13 days. A plan removes the daily limit and lets you go straight to any system, such as the immune system.

Guided courseGenetics & DNAFrom organs to genes: how traits are inherited and how gene editing treats disease.

Common questions

Is this human physiology course free?

You can take every section without paying, two sections a day, in order. A plan removes the daily limit and opens any section straight away.

What is the difference between arteries, veins and capillaries?

Arteries carry blood away from the heart at high pressure and have thick, stretchy walls. Veins bring blood back at low pressure and have valves. Capillaries are tiny vessels, one cell thick, where substances pass between blood and cells.

How do you calculate cardiac output?

Multiply the stroke volume, the blood pumped per beat, by the heart rate in beats per minute. 70 ml per beat at 70 beats a minute gives 4,900 ml per minute.

What happens in a reflex arc?

A receptor detects a stimulus, a sensory neuron carries the impulse to the spinal cord, a relay neuron passes it on, and a motor neuron carries it to an effector such as a muscle, all without waiting for the conscious brain.

How does vaccination work?

A vaccine shows your immune system the antigens of a pathogen without causing the disease. White blood cells make the matching antibodies and memory cells, so a real infection is fought off fast.

What is homeostasis?

Keeping conditions inside the body steady, such as temperature, water and blood glucose, so cells can work well.

Revision cards

Say the answer first, then flip the card to check it.

Where to go next

Learn it
Human Physiology
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