Urinary System!

I. Functions A.  Maintains homeostasis by removing

organic waste from blood, maintains blood volume and pressure, stabilizes pH, regulates ion concentration in blood plasma, and conserves valuable nutrients. "

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B. Organs of Urinary System

1.  Kidneys!2.  Renal arteries

(unfiltered blood)!3.  Renal veins

(filtered blood)!4.  Ureter!5.  Bladder!6.  Urethra!

C. Kidney 1.  Located on either side of the spinal column in your

lower back behind the pancreas and liver are the organs that function as the filtration system for your body."

2.  Each is 4-5 inches, weighs 6 oz (200g) and filters 150 liters of blood per day."

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150 Liter Fish Tank

3.  On top of each kidney are the adrenal glands which secret several hormones to help regulate our chemical balance, metabolism, and fight or flight situations by secreting epinephrine (adrenaline) into the bloodstream."

4.  Many things like anxiety, caffeine, lack of sleep, etc. can put a lot of stress on our adrenal glands and effect their function. "

D. Blood Flow in Kidneys 1.  Unfiltered blood enters through the renal arteries

branching off the aorta so urea, excess water and other waste can be removed "

2.  Filtered blood leaves the kidney through the renal veins that connect to the inferior vena cava"

3.  Kidneys filters all blood every 45 minutes.""

E. Kidney Anatomy 1.  The cortex or

outer part contains nephrons the functional unit of the kidney that filters blood."

2.  The medulla or inner part contains the loops of Henle !

II. Urine Formation A.  Purpose of urine is to maintain homeostasis by

regulating volume and composition of blood."

B.  Main metabolic waste products in urine:"1.  Urea (waste from amino acid breakdown)!2.  Creatinine (waste from creatine phosphate breakdown)!3.  Uric Acid (waste from RNA breakdown)!4.  Ammonia!5.  Excess minerals!

C.  These wastes must be secreted in water. ADH hormone regulates concentration."

1.  ADH = more concentrated urine = less water loss"2.  No ADH = less concentrated urine = more water loss"

D.  Kidney stones are hard mineral deposits that form in kidneys usually from overly concentrated urine. Stones must be passed through ureters and urethra and may be painful. Increasing water intake helps prevent stones from forming. "

E. Kidney performs 3 processes to maintain water balance and ensure vital nutrients are not lost."

III. Filtration (Step 1) A.  Blood from the renal arterioles is forced into the

glomerulus, a capillary network in the nephron."B.  The Bowman’s capsule surrounds the glomerulus and

fluid from the blood, called filtrate, filters in."C.  The filtrate contains" water, urea, glucose, " salts, amino acids and" some vitamins!D.  Big cells like proteins ! and platelets are " left behind"E. Major declines in blood pressure can stop filtration. " Hemorrhaging, shock or dehydration can cause deadly " reductions to renal function."

IV. Reabsorption (Step 2) A. Occurs in the convoluted tubules and

loops of Henle. "B.  60-70% of the water moves into the

peritubular capillaries via osmosis, most ions and small nutrients diffuse back into the blood."

C. Amino acids, fat and protein are moved via active transport back into the blood. "

D. The loops of Henle create a concentration gradient to control the concentration of urine to regulate blood volume and pressure. "

V. Secretion (Step 3) A.  Leftovers from the filtrate and any

excess ion, acids, drugs, and toxins are secreted into a the remaining fluid called urine enter the collecting duct."

B.  Urine is about 95% water, urea, salts and other substances."

C.  Urine passes through the ureter and is stored in the bladder!

D.  It is released through a tube called the urethra."

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