Kidneys and Excretory System

How Urination works

• http://health.howstuffworks.com/adam-200032.htm

Excretion

• The process of excretion involves the removal of metabolic waste.

• If wastes build up in the body, they become toxic.

• There are 4 main organs that work to remove waste from the body.

Excretion con’t

1. The skin - removes waste heat, some urea, and other

materials found in sweat2. The lungs - removes C023. The large intestine - removes solid wastes of the digestive process4. The kidneys - removes urea, uric acid, extra water and salts

Anterior View of the Urinary System

Posterior View of the Urinary System

Questions page 380 1-3

1. List 3 main functions of the kidney.

a. Eliminates wastes

b. regulation of water balance

- Also regulation of pH

- Also regulates blood pressure and is involved in the production of red blood cells.

Questions page 380 1-3 con’t

2. What is deamination and why is it an important process?

- Deamination is the removal of the amino groups from a protein (organic compound)

- Amino groups = 2 H + 1 N

Questions page 380 1-3 con’t

2 con’t

- Deamination occurs in the liver

- Important to convert excess amino acids into carbohydrates and other nutrient compounds

Questions page 380 1-3 con’t

3. How does the formation of urea prevent poisoning?- Deamination produces ammonia, a water soluble gas.

- Ammonia is extremely toxic and cannot be stored in the body.

- The liver combines two molecules of ammonia with carbon dioxide to form urea.

- Urea is 1000 times less toxic than ammonia.- Animals can store urea for short periods of time in their

bodies- Permits the controlled excretion of urine

Questions page 383 4-5

4. State the function…

Bowman’s capsule: The filtration of water and dissolved solutes happens as blood is forced from the glomerulus to the Bowmen’s capsule

Proximal tubule: Selective reabsorption of nutrients from filtrates back into the blood

Loop of Henle: Reabsorption of water and salt

Distal Tubule: secretion of substances from the blood to the urine

Collecting duct: Urine formation

• The urethra is the only part of the urinary system that differs between males and females. It is longer in males.

Questions page 319 4-5 con’t

5. List and describe the 3 processes involved in urine formation.

a. Filtration – involves the movement of fluids from the Bowman’s capsule to the glomerulus.

b. Reabsorption – involves the movement of fluids from the nephron into the interstitial fluid and eventually the capillary net.

c. Secretion – involves the selective transport of fluids from the capillary net into the nephron.