1. KEY CONCEPT The excretory system removes wastes and helps maintain homeostasis.

2. The excretory system eliminates nonsolid wastes from the body.
Nonsolid wastes are eliminated through lungs, skin, and kidneys.
Lungs exhale carbon dioxide and water vapor.
Sweat glands in skin release excess water and salts.
Kidneys filter and clean the blood to produce urine.
skin
lungs
kidneys
ureters
urinary bladder
urethra

3. The kidneys help to maintain homeostasis by filtering the blood.
cortex
medulla
renal artery
renal vein
ureter
(to bladder)
Kidneys are a pair of bean-shaped organs.
two layers: medulla and cortex
filtering units called nephrons
renal artery and renal vein

4. Kidneys have three basic functions in maintaining homeostasis.
remove waste from blood
help to maintain electrolyte, pH, and fluid balances
release key hormones

5. Nephrons clean the blood and produce urine.
Nephrons are the filtering units in the kidneys.
They clean and rebalance the blood to produce urine.
from body
to body
to body
loop of Henle
from other nephrons

6. Nephrons clean the blood in a three-step process.
The first step is filtration of the blood.
FILTRATION
Water,electrolytes,aminoacids,glucose,urea, and other small molecules diffuse out of the blood,creating the filtrate. 1
Glomerulus
Bowman’s capsule

7. The first step is filtration of the blood.
The second step is reabsorption of materials.
The third step is excretion of materials.
REABSORPTION
As the filtrate enters the rest of the tubule ,most of the materials are reabsorbed into the blood.Materials not reabsorbed make up the urine,which flows into the loop of Henle. 2
from body
collecting duct
EXCRETION
In the loop of Henle,water can be reabsorbed one final time to reduce the volume of urine.The remaining urine flows into a collecting duct that leads to the ureter. 3
to body
from other nephrons
loop of Henle

8. Injury and disease can damage kidney functions.
A kidney transplant can replaced damaged kidney.
recipient and donor tissue must match
drugs prevent tissue rejection
The daughter and son in this photo donated a kidney and liver tissue to their mother.

9. Dialysis can be used to filter and clean the blood.