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32.4 Excretory System
• Hand-in worksheet on the Excretory/Urinary System
32.4 Excretory System
KEY CONCEPTThe excretory system removes wastes and helps maintain homeostasis.
32.4 Excretory System
32.4 Excretory System
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 bladderurethra
32.4 Excretory System
• Kidneys have three basic functions in maintaining homeostasis.– remove waste from blood– help to maintain electrolyte, pH, and fluid balances – release key hormones
32.4 Excretory System
The kidneys help to maintain homeostasis by filtering the blood.
• Kidneys are a pair of bean-shaped organs.– two layers: medulla and
cortex– filtering units called
nephrons – renal artery and renal
vein
cortex
medulla
renal artery
renal vein
ureter
(to bladder)
32.4 Excretory System
Nephrons clean the blood and produce urine.
• 4. Glomerulus-filters and cleans the blood• 5. Bowman’s Capsule-holds the filtrate, molecules are
reabsorbed into the capillaries to balance the blood chemically
• 6. Loop of Henle-
Water is reabsorbed.
7. Collecting ducts-
collect urine from
nephrons and
send it to the
ureter.
from body
to body
to body
from other nephrons
loop of Henle
32.4 Excretory System
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
from other nephrons
loop of Henle
32.4 Excretory System
• 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
32.4 Excretory System
• The first step is filtration of the blood. • The second step is reabsorption of materials.• The third step is excretion of materials.
from body
to body
collecting duct
from other nephrons
loop of Henle
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
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
32.4 Excretory System
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.
32.4 Excretory System
• 1st-finish lab analysis• 2nd-collect research from Fri.• 3rd-finish handout on Excretory system• 4th – new work handout “The Urinary System”
• TEST WED.
32.4 Excretory System
• Dialysis can be used to filter and clean the blood.
