- Windpipe/ˈwɪndpaɪp/氣管Respiratory
- The trachea is a cartilage-reinforced tube connecting the larynx to the bronchi. Its lining traps dust and bacteria, which tiny hairs called cilia sweep back up towards the throat.
- Because the trachea sits in front of the oesophagus, food that goes the wrong way can block the airway.
- Lungs/lʌŋz/肺Respiratory
- The lungs are the primary organs of respiration. Gas exchange takes place in tiny air sacs called alveoli, where oxygen diffuses into the bloodstream and carbon dioxide diffuses out to be exhaled.
- The surface area of the alveoli in adult lungs is roughly the size of a tennis court.
- Kidneys/ˈkɪdniz/腎臟Urinary
- The kidneys filter roughly 180 litres of blood a day, removing metabolic waste such as urea while returning water, glucose and salts to the bloodstream. They also regulate blood pressure and stimulate red blood cell production.
- When the kidneys fail, patients rely on dialysis to do the filtering for them.
- Liver/ˈlɪvər/肝臟Digestive
- The liver performs hundreds of functions, including filtering toxins from the blood, storing glucose as glycogen, and producing bile for the digestion of fats. It is the only human organ able to regenerate lost tissue.
- Alcohol is broken down in the liver, which is why heavy drinking can cause liver disease.
- Stomach/ˈstʌmək/胃Digestive
- The stomach is a muscular sac that begins protein digestion. Its glands secrete hydrochloric acid and the enzyme pepsin, while a thick layer of mucus stops the acid from digesting the stomach wall itself.
- Stomach acid is strong enough to dissolve metal, yet the mucus lining is replaced fast enough to protect the organ.
- Large intestine/ˌlɑːrdʒ ɪnˈtestɪn/大腸Digestive
- The large intestine reabsorbs water and electrolytes from indigestible food residue and compacts it into faeces. It also hosts trillions of gut bacteria that ferment fibre and synthesise vitamin K.
- A diet high in fibre keeps material moving through the large intestine and supports a healthy gut microbiome.
- Small intestine/ˌsmɔːl ɪnˈtestɪn/小腸Digestive
- The small intestine is where most nutrient absorption occurs. Its inner surface is covered with finger-like projections called villi, which increase the surface area available for absorbing sugars, amino acids and fatty acids.
- Enzymes from the pancreas enter the small intestine to complete the breakdown of carbohydrates and proteins.
- Bladder/ˈblædər/膀胱Urinary
- The bladder is an expandable muscular organ that stores urine delivered by the ureters. Stretch receptors in its wall signal the brain once it is about half full, triggering the urge to urinate.
- The bladder wall contains a muscle called the detrusor, which contracts to expel urine.
- Heart/hɑːrt/心臟Circulatory
- The heart is a four-chambered muscular organ that circulates blood through the body. The right side sends blood to the lungs to collect oxygen, while the left side pumps oxygen-rich blood out into the arteries.
- Regular aerobic exercise strengthens the heart so that it pumps more blood with each beat.
- Brain/breɪn/大腦Nervous
- The brain coordinates the nervous system. It processes sensory information, regulates vital functions such as breathing and heart rate, and is responsible for higher functions like language, reasoning and memory.
- Although it makes up only about 2% of body weight, the brain consumes roughly 20% of the body's energy.