1. Human Excretory System

2. Human Excretory System
Excretion is the removal of metabolic wastes from the body, including toxic chemicals, excess water, carbon dioxide and salts.
Excretory Organs
Skin—removes water, salts & nitrogen wastes in the form of sweat.
Lungs—eliminate CO2, water vapor & heat in exhaled air
Kidneys—excrete the majority of metabolic waste products from the body
Human Excretory System
Normal metabolic activity generates waste products that must be eliminated to sustain homeostasis. Ammonia (a product of protein metabolism) is converted to urea for elimination. Carbon dioxide, generated from cellular respiration, is removed from the lungs. Excess water and salts must be eliminated in order to maintain osmotic and pH balance.
The skin removes water, salts and nitrogen wastes in the form of sweat.
The lungs eliminate carbon dioxide, water vapor and heat in exhaled air.
The kidneys excrete the majority of metabolic waste products from the body. Each kidney contains about one million functional filtering units called nephrons.
References:
Campbell, N.E. & Reece, J.B. (2002). Biology,(6th ed.). San Francisco: Benjamin Cummings.
Raven, P.H. & Johnson, G.B. (2002). Biology, (6th ed.). McGraw-Hill.

3. The Urinary System
Works with the lungs, skin, & intestines-all of which also
excrete wastes-to keep the chemicals and water in your
body balanced—helps you achieve homeostasis!
Your urine is almost 95% water but also
contains salts & urea (a waste product of
protein metabolism)
Human Excretory System
Normal metabolic activity generates waste products that must be eliminated to sustain homeostasis. Ammonia (a product of protein metabolism) is converted to urea for elimination. Carbon dioxide, generated from cellular respiration, is removed from the lungs. Excess water and salts must be eliminated in order to maintain osmotic and pH balance.
The skin removes water, salts and nitrogen wastes in the form of sweat.
The lungs eliminate carbon dioxide, water vapor and heat in exhaled air.
The kidneys excrete the majority of metabolic waste products from the body. Each kidney contains about one million functional filtering units called nephrons.
References:
Campbell, N.E. & Reece, J.B. (2002). Biology,(6th ed.). San Francisco: Benjamin Cummings.
Raven, P.H. & Johnson, G.B. (2002). Biology, (6th ed.). McGraw-Hill.

4. How the Urinary System Functions
1. During circulation, blood passes through the kidneys in order to deposit water, minerals, salts and urea.
2. The kidneys filter the wastes from the blood, forming a liquid called urine.
3. The kidneys funnel the urine into the bladder along two separate tubes called ureters.
4. The bladder stores the urine until muscular contractions force the urine out of the body through the urethra.
Kidney
Ureter
Urinary
Bladder
Urethra
Human Urinary System
The urinary system, consisting of the kidneys, ureters, urinary bladder and urethra, is responsible for eliminating the majority of metabolic wastes from the body.
The functional unit of the kidney is the nephron. Each nephron is made of a cup-shaped portion called Bowman’s capsule, tubules and a network of capillaries. Blood pressure within a knot of capillaries (called the glomerulus) increases, causing most of the fluid of the blood to enter Bowman’s capsule. This fluid is called filtrate. As the filtrate passes through the tubule portion of the nephron, materials needed by the body are reabsorbed and the remainder of the filtrate becomes urine. Proper functioning of the kidney is essential to maintaining homeostatsis in the body.
References:
Raven, P.H. & Johnson, G.B. (2002). Biology, (6th ed.). McGraw-Hill.
Image References:
LifeART. (1998). Super Anatomy Collection 1-9. Baltimore, MD: Williams & Wilkins, All rights reserved.

5. Kidneys The functional unit of the kidney is the nephron.
There are over a
million nephrons
in each kidney!!
Nephrons filter out
wastes from the
blood—the rest gets
reabsorbed into the
blood stream

6. Inside the Nephron The nephron consists of a cup
shaped capsule containing
capillaries & the glomerulus,
and a long renal tube.
Blood flows into the kidney
through the renal artery, which
branches into capillaries
associated with the glomerulus.

7. Inside the Nephron
Water, urea, and salts filter into the capsule.—blood does not actually enter The filtrate flows through the proximal tubule, which include the loop of Henle, and then into the distal tubule. The distal tubule empties into a collecting duct.

9. What causes problems in the urinary system?
Problems can be caused by aging, illness, or injury. -As you age, kidneys lose some of their ability to remove wastes from the blood. -Also, the muscles throughout your urinary system tend to weaken. -Illness or injury can also prevent the kidneys from filtering the blood completely or block the passage of urine.

10. What happens if the kidneys don’t work properly?
If your kidneys are diseased or don’t work properly, the buildup of waste in your system will eventually lead to death. Some kidney diseases can be with medication. Severe kidney diseases require more intense treatment such as dialysis (a patient’s blood is pumped through a dialysis machine which filters the waste for them—patients can spend up to 60 hours each week on dialysis!!) Eventually, some patients may require a kidney transplant (can be donated since people can live with only one functioning kidney)

11. Interesting Facts
Almost 440 gallons of blood is passed through the kidneys on a daily basis
Adults eliminate almost 1.5L of urine each day
The bladder can hold up to 2 cups of urine comfortably for 2 to 5 hours
Urine is sterile & almost odorless when it leaves the body.
You can die of water intoxication!! In 2007, a woman in California participated in a radio station's contest that involved drinking the maximum water without having to visit the restroom. She won the contest, however, was found dead the next day in her house.

12. Diagram of the Urinary System