The human body
The kidneys and the urinary system
The kidneys filter blood and regulate fluid, electrolyte, and acid–base balance. Urine travels through the ureters to the bladder and exits through the urethra.
The kidneys
Two bean-shaped organs at the back of the abdomen. Together they filter about 120–180 litres of blood plasma a day, keeping what the body needs and making urine of the rest.
- MeasuredNephrons: 0.9–1 million per kidney on average (about 200,000 to over 2.5 million)
- MeasuredYoung men: right 129 g, left 137 g; young women: right 108 g, left 116 g
- MeasuredLength on CT: right 108.5 ± 12.2 mm, left 111.3 ± 12.6 mm
The bladder
A muscular reservoir in the pelvis that stores urine arriving from the kidneys through the ureters.
- EstimateHolds 1.5–2 cups, about 350–475 mL
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 digestive 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