1. Excretion – removes cellular waste
Excretory System
Excretion – removes cellular waste
Your excretory system collects wastes produced by cells and removes these wastes from your body. The removal process is known as excretion.

2. Cellular Waste Heat Water – H2O Salts Carbon dioxide - CO2 Urea
W/O excretion poisonous wastes build up in blood, cells, and tissues.
Could lead to serious illness & eventually DEATH!

3. Four Organs of the Excretory System
The lungs excrete CO2 as a waste products
The skin rids the body of wastes through the sweat glands.
The liver excretes bile and converts nitrogenous waste from the break down of proteins into urea.
The kidneys are the major organ in the urinary system.

4. Filters nitrogen out of your blood  UREA
Liver

5. Liver Produces Urea Functions in Excretion Forms Urea
Changes toxic wastes (ammonia – from break down of amino acids) to Urea.
Urea  Blood  Kidneys
Filtered out & excreted in Urine

6. DETOXIFIES the blood (removes toxins such as drugs and alcohol)

7. A liver is about 3 pounds in an average human and it is rubbery to touch.

9. The Main Parts of the Excretory System

10. Kidneys & Urinary System
Two
Fist sized
Bean shaped

11. Each kidney is about 4 ½ inches long
Weight is 4 – 6 ounces
The urine output varies from 1 to 2 liters per day.

12. The ureters are tubes that carry urine from the kidneys to the urinary bladder.
The urinary bladder temporarily stores urine until it is released from the body.
The urethra is the tube that carries urine from the urinary bladder to the outside of the body.
The outer end of the urethra is controlled by a circular muscle called a sphincter.
skin
lungs
kidneys
ureters
urinary bladder
urethra

13. two layers: medulla and cortex
filtering units called nephrons
renal artery and renal vein
cortex
medulla
renal artery
renal vein
ureter
(to bladder)

14. Contains nephrons

15. Nephrons clean the blood and produce urine.
from body
to body
from other nephrons
loop of Henle
There approximately 1 million nephrons in each kidney

16. Nephrons clean the blood in a three-step process.
The first step is filtration of the blood.
FILTRATION
Water, electrolytes, amino acids, glucose, urea, and other small molecules diffuse out of the blood, creating the filtrate. 1
Glomerulus: Network of capillaries
Bowman’s Capsule: Encases the glomerulus
Glomerulus
Bowman’s capsule
The body’s entire volume of blood is filtered every 45 min

17. from body collecting duct to body from other nephrons loop of Henle
The first step is filtration of the blood.
The second step is reabsorption 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

18. 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
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

19. Ureters Narrow muscular tubes Connect Kidney  Bladder Bladder
Muscular sac
Stores Urine
Expand to fill
Sphincter muscle relaxes
Urine squeezed into Urethra

20. Urinary bladder

21. Urinary System - endpoint
Urethra
Tube leading from Bladder  outside of body

22. Produce URINE
Water, salt and urea

29. 2.Which organ produces urea?
1.Identify A, B, and D.
2.Which organ produces urea?
3.What is the function of D?
4.What does organ A excrete?
5.Which organ detoxifies the blood?
Lungs
Urea
Filter urea from the blood.
Liver
CO2, H2O
Kidney
Liver

30. Identify structures A, B, C, and D. Which structure produces urine?
What is the path of urine?
What are the 2 main functions of A?
5. What stores urine?
6. What is the function of D?
Kidney
Kidneys
Kidney, ureters, urinary bladder, urethra
Ureter
Filter the blood
Regulate the amount of H2O in blood.
Urinary bladder
Urinary bladder
Urethra
Transport urine out of body.