Human Body Systems Explorer
Tap any organ on a labelled body diagram to learn what it does, watch food, blood, air and nerve messages travel through the body, then test yourself with labelling games and quizzes.
The human body is studied as six main organ systems: digestive, circulatory, respiratory, skeletal, nervous and excretory. Food travels mouth, oesophagus, stomach, small intestine, large intestine, rectum and anus; the heart pumps about 5 litres of blood through a double circulation; and an adult skeleton has 206 bones.
System
Organs
Journey
Label test
Pick a label, then click that part on the diagram. Score a point for each label you place right first time.
Body systems quiz
10 multiple-choice questions, shuffled every time. Choose a system or mix them all.
Your best scores
Review
See how your body works together
Every organ belongs to a team called an organ system. Explore six systems from the NCERT syllabus — from chewing your food to filtering your blood.
Choose a system
Digestive, circulatory, respiratory, skeletal, nervous or excretory.
Tap the organs
Hover or tap any part to read its job, key facts, a fun fact and the class that studies it.
Watch the journey
Follow food, blood, air, a nerve message or urine step by step through the body.
Test yourself
Place the labels on the diagram, then take a 10-question quiz with instant feedback.
Digestion in order
Mouth → oesophagus → stomach → small intestine → large intestine → rectum → anus. The liver, gall bladder and pancreas add juices but food never passes through them.
Starch → sugar · Proteins → amino acids · Fats → fatty acids + glycerol
Double circulation
Blood passes through the heart twice in one round: body → right side of heart → lungs → left side of heart → body. The septum keeps oxygen-rich and oxygen-poor blood apart.
Breathing vs respiration
Breathing moves air in and out of the lungs. Respiration happens in every cell:
Glucose + Oxygen → Carbon dioxide + Water + Energy
The reflex arc
Receptor → sensory nerve → spinal cord (relay neuron) → motor nerve → muscle. Reflexes skip the thinking part of the brain, which is why they are so fast.
Human Body Systems Explorer — your questions
What are the main organ systems in the human body?
The six studied in school are the digestive system, which breaks down food; the circulatory system, which carries oxygen and nutrients; the respiratory system, which takes in oxygen and removes carbon dioxide; the skeletal system, which gives shape and protection; the nervous system, which controls and coordinates; and the excretory system, which removes liquid waste.
What is the correct order of the human digestive system?
Mouth, oesophagus, stomach, small intestine, large intestine, rectum and anus. The liver, gall bladder and pancreas are digestive glands that pour juices into the canal, but food never passes through them. Starch becomes sugar, proteins become amino acids and fats become fatty acids and glycerol. The whole alimentary canal is about 9 m long.
What is double circulation?
Blood passes through the heart twice in one complete round. Oxygen-poor blood goes from the body to the right side of the heart and on to the lungs, then returns oxygen-rich to the left side of the heart and out to the body. The septum keeps the two kinds of blood from mixing, which keeps the oxygen supply efficient.
What is the difference between breathing and respiration?
Breathing is the physical movement of air in and out of the lungs, carried out by the diaphragm and rib muscles about 15 to 18 times a minute at rest. Respiration is the chemical process inside every cell: glucose plus oxygen gives carbon dioxide, water and energy. Breathing supplies the oxygen that respiration uses.
What is a reflex arc?
A reflex arc is the short nerve pathway that produces an automatic response. A receptor in the skin detects the stimulus, a sensory nerve carries the message to the spinal cord, a relay neuron passes it straight to a motor nerve, and the muscle acts. Because the message does not wait for the thinking part of the brain, the response is very fast.
How many bones are there in the human body?
An adult has 206 bones. A newborn baby has many more, around 300, because several bones are still in separate pieces that fuse as the child grows — a baby's skull has soft spots that close up later. Bones meet at joints: fixed in the skull, hinge at the elbow and knee, ball-and-socket at the shoulder and hip, and pivot at the neck.
How do the kidneys clean the blood?
Blood enters each kidney through the renal artery and is filtered in millions of tiny units called nephrons. Useful substances such as glucose, salts and most of the water are reabsorbed into the blood, and the remaining waste leaves as urine. Urine flows down the ureters to the urinary bladder and is passed out through the urethra.