The human body
The digestive system
The digestive tract breaks down food, absorbs nutrients and water, and moves waste onward. Accessory organs contribute bile and digestive enzymes.
The tongue
Your tongue is covered in tiny bumps that hold taste buds. They detect five basic tastes (sweet, salty, sour, bitter and umami, a savoury taste), and every part of the tongue can sense all five.
- EstimateAbout 50–150 receptor cells in each taste bud
The oesophagus
A muscular tube about 25 cm long that carries food from the throat to the stomach. Waves of muscle squeeze the food down, so you could even swallow upside down.
The stomach
A muscular chamber between the esophagus and small intestine. It stores and mixes food with acid and enzymes before releasing it into the duodenum.
The liver
A large organ beneath the right side of the diaphragm. It processes absorbed nutrients, produces bile, and synthesizes many proteins carried in the blood.
- MeasuredYoung men: 1,561 g on average (968–1,860 g)
- MeasuredYoung women: 1,288 g on average (603–1,767 g)
The gallbladder
The liver makes bile all the time; the gallbladder, a small pear-shaped bag under the liver, stores and concentrates it. After a fatty meal it squeezes the bile through the bile ducts into the duodenum to help break up fat.
- MeasuredEmpties 76–86% after a fatty meal (one small, older study)
The pancreas
An abdominal organ with digestive and endocrine roles. It supplies enzymes to the small intestine and releases hormones including insulin and glucagon.
- MeasuredReference mass: 140 g in men
The small intestine
The longest part of the gut: about 3 metres with its muscles working, 6–7 metres when relaxed and laid out. Most digestion and nearly all absorption of nutrients happens here.
- MeasuredLength at surgery, relaxed: 690 cm on average (350–1,049 cm)
- EstimateInner width: about 2.5 cm
- MeasuredInner lining: about 30 m² of the whole gut’s 32 m²
- EstimateThe jejunum is about the first two fifths, the ileum the last three
- DrawnIn this model the jejunum and the ileum are one coiled piece
The large intestine
The last part of the gut, about 1.5 metres. It absorbs water and salts and is home to trillions of bacteria that help digestion.
- MeasuredLength: 150.3 ± 18.5 cm (110–196 cm) by CT scan
- MeasuredA little longer in women: 154.3 cm against 147.1 cm in men
- EstimateInner width about 4.8 cm; lining about 2 m²
The appendix
The cecum is the pouch where the large intestine begins. Hanging from it is the appendix, a thin tube about 5–10 cm long. It isn’t useless: it holds immune tissue and may keep a reserve of helpful gut bacteria.
- EstimateAppendix: 5–10 cm long, 0.5–1 cm wide
In Endo-View
In the human atlas you can peel the body layer by layer down to these organs, turn it, take it apart and click any part for its card.
Every number is labelled measured, an estimate or drawn: how we know.
More of the body
The heart and blood vessels The lungs and airways The kidneys and the urinary system The brain and the nervous system
The journey to life
What Happens to Sperm After Ejaculation How Sperm Get Through the Cervix: Cervical Mucus Sperm in the Uterus: The Race and the White Blood Cells Sperm in the Fallopian Tube: Waiting for the Egg The Human Egg Cell: Its Size and Its Layers How Fertilisation Works: Sperm Meets Egg The Zygote and the First Cell Divisions What Is a Blastocyst? Days 3 to 6 How Implantation Works: Days 6 to 12 The Fetus from Week 10 to Week 20 Pregnancy Week by Week: The Fetus to Week 40 How Birth Works: Labour and the First Breath The Embryo Week by Week: Weeks 4 to 10