Chapter 30.4:Excretory System

Role of the Excretory System- Removes waste from the body

- Excretion is the process by which metabolic wastes are eliminated to maintain homeostasis

Structures of the Excretory System

- Skin- Excretes water and salts

- Lungs- Excrete carbon dioxide

- Liver- Converts nitrogen waste into urea

Structures of the Excretory System

- Kidneys- Filter excess water, urea and

metabolic waste from blood

- Ureters- Transport urine from kidneys to

bladder

- Urinary bladder- Stores urine

- Urethra- Releases urine outside the body

Homeostasis and the Kidneys- When waste builds up in the

blood, it increases filtration by the kidneys

- The pituitary gland releases antidiuretic hormone (ADH) if blood fluid levels are low, causing the kidneys to reabsorb more water into the blood

Kidney Disorders- Kidney stones

- Calcium, magnesium, and other salts can crystallize in the kidney

- Kidney damage- High blood pressure can harm

the filtering mechanism of the kidney

- Kidney failure- Occurs when kidneys can no

longer filter the blood, and will lead to death if untreated

Kidney Disorder Treatment

- Dialysis- Uses a machine to filter wastes

from the blood

- Kidney Transplant- Leaves damaged kidneys in place

unless they are secreting toxins- Adds donor kidney and ureter

below old kidney- A human can function with only one

kidney