The Excretory System The system includes organs that eliminate NON-SOLID wastes from the body

 Specialized cells work together to: –Store waste –Remove waste  Major Organs of this system include: -Kidneys -Bladder -Ureters -Urethra The Excretory System Song!

Vocabulary  Kidneys – filter wastes and excess water from the blood.  Urea: a nitrogen waste product formed when proteins are used by the body.  Ureters: long narrow tubes that carry urine to the bladder  Bladder: a muscular pouch that stores urine –An adult bladder can stretch to hold about 2 cups of urine

Vocabulary (Con’t)  Sphincter: ring like muscle that prevents urine from leaking out of the bladder and is controlled by nerves sending messages to the brain  Urethra: a muscular tube that leads the urine out of the body  Nephron: tiny, tube-shaped structures inside each kidney that are used as filters

I. The Kidneys  The kidneys are a pair of fist-sized organs located on either side of the spinal column near the lower back.  You can live with only 1 kidney!  Kidneys excrete urea, minerals and excess water.  Kidneys regulate the amount of water we need to maintain in our bodies.

The Kidneys…  Every drop of blood in your body is filtered by your kidneys more than 300 times per day!  The kidneys produce and excrete a waste product known as urine.

The Flow… 1. Waste products from cells diffuse into the blood. 2. This waste must be removed ASAP 3. Blood flows through Liver where excess proteins are changed into ammonia (toxic) then into urea (less toxic) 4. Urea diffuses into bloodstream

The Flow… 5. Blood moves out to the kidneys where all liquid waste is filtered out *1 liter of blood every minute! 6. Each kidney is made of millions of tiny tubules called nephrons 7. Inside the nephrons, the waste mixes with water and moves to the ureter 8. The Ureter is connected to the bladder which stores the waste as urine.

Nephrons  There are over 1 million nephrons in each kidney!!  See it! See it!

Interactive Body Systems…  How do the kidneys clean the blood?  As waste-laden blood enters the kidney through the renal artery, the kidney removes urea, excess water and minerals, and other waste products.  The clean, filtered blood leaves a kidney through the renal vein and returns to circulation.

Did you know?  Urine or “Pee” is… –95% water –2% urea –1% salts –<1% chemicals (poisons, pigments, etc)

Excretory isn’t just pee!  Lungs –Remove carbon dioxide as a part of respiration  Skin –Excretes sweat through glands all over your body Helps maintain salt levels in the body Mainly a process to help temperature control

The Skin  The skin excretes excess water, salts, and a small amount of urea in sweat through small holes in your skin called pores.  By releasing sweat in very small amounts, this process eliminates wastes even when you may not think you’re sweating.

Control of Kidney Function  The activity of the kidneys is controlled by the composition of the blood itself.  For example, if you eat salty food, the kidneys will respond to the excess salt levels in your blood by returning less salt to your blood during reabsorption.

Kidney Function and Hydration  The color of your urine is an indicator of how hydrated you are.  A pale yellow color indicates that you are well-hydrated because your kidneys are releasing a good amount of water.  A darker color indicates that the water level in your blood is low, causing your kidneys to conserve water.

II. Signs of Disease Doctors analyze urine for disease;  Normal urine contains water, urea and trace minerals.  Sugar in urine indicates Diabetes  Protein in urine indicates the kidneys are not working and the person, or animal, is very sick.

Kidney Disorders-Kidney Stones  Substances such as calcium, magnesium, or uric acid salts in the urine can crystallize and form kidney stones.  When kidney stones block a ureter, they cause pain.  Kidney stones are often treated using ultrasound waves, which pulverize the stones into smaller fragments that are eliminated in the urine.

Kidney Disorders- Kidney Failure  When kidneys can no longer cleanse the blood and maintain homeostasis, a person is said to be in kidney failure.  A patient with kidney failure must receive dialysis or undergo a kidney transplant.  During dialysis, a machine performs the role of the kidneys. The patient’s blood is pumped through the machine, cleansed, and pumped back into the body.