3D-HuBEd No.7 -KIDNEY-

The function of the urinary system is to rid the bloodstream of waste and other impurities. It consists of the kidneys, the ureters and the bladder.

Kidneys are about the size of a fist and shaped like beans. Their function is to filter the blood of impurities. There are two of them, one on each side of the spine in the abdomen. Even if one is lost to disease or by surgery, the other would usually provide enough functionality to sustain life.

The waste liquid is called urine, and is carried from the kidneys through ducts called ureters to the bladder. There it is stored, and when the bladder is near full, it is expelled through the urethra.

Refer to chapter 0 for more information on how to use this textbook.

7.1 The Structure of the Urinary System

7.2 The Formation of Urine

7.1 The Structure of the Urinary System

Kidneys are in the abdomen, close to the spine. The left kidney is below the pancreas, and the right kidney is below the liver. The right kidney is usually located slightly higher than the other. They are shaped like beans, about 12cm in height, 6cm across and 3cm thick. Each kidney weighs about 150 grams. On the side close to the spine is a recessed area, where an artery and autonomous nerves go in and a vein and a urethra come out.

Inside the kidneys are small clusters of blood vessels and convoluted tubules. These clusters are called nephrons. There are about one million of them in each kidney. The tiny blood vessels are surrounded by a small sac called the Bowman's capsule. It is in this capsule that the impurities are removed from the blood. The impurities flow into the convoluted tubules. The tubules gather into the ureters, which connect the kidney to the bladder.

the 3-D figure with the name: $HOME/hubed/yyHarakid.tar.gz

7.2 The formation of Urine

The impurities in the blood are removed in the Bowman's capsule, along with water and minerals. As this mixture travels through the tubules, water and minerals are absorbed back into the blood vessels. The resulting liquid is called urine.

The average amount of urine for an adult is about one to two liters per day. This amount varies each day, according to the amount of the water intake, the weather and the amount of the sweat.

the 3-D figure with the name: $HOME/hubed/yyKidney.tar.gz