1. Ch. 8.2
The Excretory System

2. 1. systems that form the excretory system
digestive system- undigested food leaves through large intestine
respiratory system- carbon dioxide and water out
skin- salt and organic substances leave through sweat
urinary system- water, metabolic wastes, and salts out in urine

3. 2. urinary system rids the blood of wastes made by the cells
controls blood volume by removing extra water made by body cells during respiration
2. urinary system

4. 3. regulating fluid levels
hypothalamus- in brain, monitors the amount of water in the blood
too much water in blood, hypothalamus releases a hormone that tells kidneys to return less water to blood and release more as urine
specific amount of water is important for movement of gases and excretion of solid waste
also balances the amounts of salts
3. regulating fluid levels

5. 4. kidneys 5. nephrons made of about 1 million nephrons
-filter blood that contains wastes collected from cells, all blood in body passes through in 5 minutes
made of about 1 million nephrons
4. kidneys
filtering units in the kidneys
made of a cuplike structure and a tubelike structure called a duct
5. nephrons

6. 6. stages of filtering in kidneys
stage 1: water, sugar, salt and wastes from blood pass into cuplike structures, red blood cells and protein are left in blood, water is squeezed into a narrow tubule
stage 2: most water, sugar and salt reabsorbed and returned to blood and purified blood returned to body through renal vein, wastewater becomes urine

7. average sized person makes 1 liter of urine per day
leaves kidneys through ureters and go into bladder
carried out of body through urethra
7. urine
8. ureters
- tubes that lead from each kidney to the bladder

8. 9. bladder
an elastic, muscular organ that holds urine until it leaves the body
can hold about 0.5 liters of urine
10. urethra
- a tube that carries urine from the bladder to the outside of the body

9. 11. other organs of excretion
liver- filters the blood to remove wastes
extra amino acids changed to urea that leaves in urine
hemoglobin from broken down red blood cells becomes part of bile

10. 12. What happens if wastes are not removed?
wastes can build up and act as poison
extra water can cause ankles and feet to swell
fluid can build up around the heart, causing it to work harder to move blood to the lungs
unbalance of salts can cause kidney damage
infections in bladder can spread to kidneys
blockages in ureters or urethra
12. What happens if wastes are not removed?

11. 13. detecting urinary diseases
change in urine color- kidney or liver problems
high levels of glucose- diabetes
high levels of protein called albumin- kidney disease or heart failure
- an artificial kidney machine used to filter blood if both kidneys fail
14. dialysis