Urinary System

EQ: Diagram the process and organs involved in excretion. ● Process of removing cell waste from cell activity.● NOT removal of undigested food material!

○ Egestion is removal of digestive waste● Cell waste products: CO2 (cell respiration), Nitrogen

(protein digestion), and salts

Why do we need to excrete nitrogen? ● All organisms produce● Nitrogen is toxic and must be removed● Three different types of nitrogen waste

○ Ammonia: very toxic → aquatic animals ○ Urea: Dilute ammonia w/ water → land animals

■ Lose H2O ○ Uric Acid: not toxic, conserves water → birds & insects

Where does excretion occur in humans? ● Excrete: Urea, salt and water● Urinary system: Kidneys, ureter, urethra and bladder● Kidneys

○ Remove waste from blood○ Maintain blood pH○ Control water content of blood

Anatomy of Kidneys● Start at Thoracic

Vertebrae 12● Surrounded in

fat→ protects & holds in place

● Renal hilum: leads into sinus (opening)

Nephron Anatomy● Functional unit of kidney● Each kidney has 1 mil. ● Form urine● Made up of

○ Renal corpuscle- glomerulus (capillaries) & Bowman’s capsule

○ Renal Tubule

Kidney Physiology: 1. Blood enters through renal artery

2. Blood is filtered through millions of nephrons

3. Wastes pass through ureter to the bladder as urine

4. Clean blood returns to body through renal vein

5. Bladder stores urine and passes urine through the urethra

Nephron Physiology1. Renal Corpuscle & Filtration: filter out

water, urea, salt, glucose and amino acids

2. Renal Tubule & reabsorption: reabsorb materials that the body needs (blood plasma, food & water)

3. Tubular secretion: collect wastes as urine and passes to the bladder

→ Kidney’s filter your blood 6x / day

→ 99% H2O reabsorbed

Urine and the Urinary System Anatomy● 95% water, 5% other solutes (urea, Sodium [Na+],

Potassium [K+]) ● Ureter: tubes that carry urine from kidney to bladder

○ If Calcium or Uric Acid Salts crystallize forms kidney stones- if too big blocks urine drainage causing pain as peristalsis occurs in the ureter → surgically removed or use sound waves to break up

Urinary System Anatomy● Bladder: stores urine (up to 1 pt, 12 cm long)

○ When empty collapses into a triangle shape with rugae (folds) ○ Bladder wall has three layers- one is a thick muscular layer called the

detrusor muscle○ Trigone: three openings into the bladder

■ Two for ureters■ One for urethra

*Important because this is the

region where infections occur.

Urinary System AnatomyUrethra: muscular tube drains urine from bladder

○ Between bladder & ureter = internal sphincter (valve) to avoid “leaking”

○ External sphincter: surrounds urethra, skeletal muscle (_______ control)

○ Female urethra- 5 cm long, males: 20 cm long■ Urinary Tract Infections: more common in

females, why?

Micturition a.k.a urinatingThree things must happen simultaneously

1. Detrusor muscle contracts (bladder muscle) 2. Internal sphincter relaxes3. External sphincter relaxes

Micturition reflex: bladder fills → stretch receptors send a message to brain → you become aware bladder is full → you choose to void or not void

Incontinence: inability to control bladder → pregnancy, aging, nervous system problems or emotional problems

Label and Define on Worksheet: ● Kidney Renal Vein● Ureter Nephron● Urinary Bladder Renal Pyramids● Urethra● Renal Capsule● Hilum● Renal Sinus● Renal Pelvis● Calyces● Renal Cortex● Renal Medulla● Renal artery