1. The Excretory system

2. Functions of the Excretory System
Removal of waste products from the body

3. Parts of the Excretory System
Kidneys-remove waste products from the blood; maintain blood pH; regulate water content in blood and regulates blood volume
Ureters- carries urine to the bladder from the kidneys
Bladder- sac-like organ that collects urine
Urethra-tube that allows urine to pass from the body

4. Parts of the Excretory System
Renal Artery
Kidneys
Ureters
Bladder
Urethra

5. Functional Units of the Kidney
Nephrons-Cells in Kidney Tissue
Small independent processing unit
Each has its own blood supply

6. Filtration Passing a liquid or gas through a filter to remove waste
Filtration of blood mainly takes place in the glomerulus (enclosed by bowman's capsule)
Glomerulus

7. Filtration Cont.
Materials filtered from the blood are called filtrate. (water, salts, vitamins)

8. Reabsorption
The process in which liquid is taken back to the blood is called reabsorption.
Amino acid, fat, glucose and most water is removed from the filtrate and returned to the blood.

9. Reabsorption Cont.
Urine, which contains urea, excess salts and water, is concentrated in the loop of Henle.
Loop of Henle

10. Reabsorption Cont.
Filtered blood is returned to the blood stream and urine moves to the urinary bladder through the ureters.
The bladder holds the urine until it is excreted from the body through the urethra.

11. Control of Kidney Function
The kidney’s job is to maintain the composition of the blood.
Kidney activity is largely controlled by the composition of the blood.

12. Feedback Mechanisms in the Excretory System
If the amount of water in the blood is high then less water will be returned to the blood stream and more water will be secreted in the urine.
Stimulus: ____________
Response:____________
Feedback: ___________

13. Feedback Mechanisms in the Excretory System
If the amount of salt in the blood is high then less salt will be returned to the blood stream and more salt will be excreted in the urine. Stimulus:____________ Response:___________ Feedback:___________

14. Homeostasis by Machine
If kidney function is disrupted due to damage or disease serious medical problems can arise.
If one kidney is damaged or diseased a person can survive with just one.
If both kidneys are damaged one of two things need to happen for a person to be able to survive.

15. Homeostasis by Machine Cont.
The person can receive a kidney transplant or
The person can receive dialysis.

16. Dialysis is where blood is filtered through a machine that filters out waste products and then returned to the body.