Health 10-3

How is dialysis used to treat kidney failure?

During dialysis, a machine is used to filter wastes form the blood. Tubes carry blood form the body through the machine. The machine removes wastes and excess water. Then the blood is returned to the body. Dialysis must be performed three times a week for three to five hours. Many complications can arise.

glomerulus

During the first stage of waste removal, blood enters the kidneys. Here, the blood flows through smaller and smaller blood vessels until it reaches a cluster of tiny blood vessels in a nephron called glomerulus. Urea, salts, glucose, and some water are filtered form the glomerulus into a thin-walled capsule. Blood cells and most protein molecules usually remain in the blood because they are too large to pass through the walls of the glomerulus.

nephrons

Each kidney contains about a million nephrons, tiny filtering units that remove wastes and produce urine.

urea

The liver converts impurities and poisons in the body to less harmful substances. For example, the liver forms urea from a harmful waste product of protein breakdown. Urea can be safely transported via blood to the kidneys.

What is the body's main organ of excretion? What are other organs in the excretory system?

The major organs of excretion are the kidneys, which are part of the body's excretory system. The other organs of the excretory system include the ureters, bladder, and urethra.

Briefly describe the process of filtration and urine production that occurs in the nephrons.

The nephrons filter wastes in stages. First, both needed materials and wastes are filtered from the blood. Then, most needed materials are returned to the blood, and the wastes are eliminated from the body.

urine

The wastes are eliminated in urine, a watery fluid produces by the kidneys that contains urea and other wastes. Urine flows form the kidneys, through the other organs of the excretory system, and out of the body.

What are two ways that you can help keep your excretory system healthy?

To help your kidneys function at their best, it is important to drink plenty of water and to see a doctor if you have symptoms of an infection.

kidneys

the major organs of the excretory system, which filter urea and other wastes from the blood.

Excertion

the process by which the body collects and removes wastes.