1. URINE FORMATION

2. 2. Reabsorption
1. Filtration
3. Secretion

3. GLOMERULAR FILTRATION
180 liters per day filtered (4X total body water)
Filters water & dissolved substances (plasma)
Hydrostatic pressure forces substances out of capillaries
As osmotic pressure increases in the capillaries, filtration decreases

4. Con’t
Filtration is also regulated by changes in blood pressure or blood volume or by vasodilation
Renin (enzyme) regulates filtration by reacting to
a. Drop in blood pressure
b. Sympathetic stimulation
c. Decrease in ions (Na+, K+, Cl-)

5. TUBULAR REABSORPTION
Substances are transported out of the tubular fluid & into intersticial fluid
PURPOSE: reclaim materials body needs & remove waste
MOVEMENTS:
A. Lipid soluble
B. Channel proteins
C. Active transport

6. CON’T Most absorption takes place in the proximal convoluted portion
Examples of substances that get reabsorbed: proteins, water, vitamins, amino acids, glucose, creatin, uric acid, urea, Na+, K+
Water is reabsorbed by osmosis
As Na+ reabsorption increases, so does water reabsorption

7. Primary substances UREA: Byproduct of amino acid metabolism
URIC ACID: byproduct of organic base (in nucleic acids) metabolism

8. TUBULAR SECRETION
Substances move from capillaries into tubule to be secreted out of body
Active transport
Examples of substances secreted: K+, H+, creatine, histamines, antibiotics, narcotics, ammonia
Secretion of H+ ions regulate body fluid pH

9. URINE COMPOSITION 95% Water Urea Uric acid Trace amts of amino acids,
electrolytes

10. URINE PRODUCTION Produce 0.6-2.5 liters urine per day AFFECTED BY:
a. Fluid intake
b. Environment: temp/humidity
c. Emotional condition
d. Body temperature/respiration

11. Urine tells a lot about your body!
Cloudy urine indicates high # of RBC, WBC, bacteria, food pigments, or poisons
Urine pH ranges 4.5-8; a urine pH out of this range could be result of diet or infection (urinary tract infection)

12. CON’T Calcium crystals can result in kidney stones
Bilirubin can indicate liver disease
Too much sugar (glucose) indicates diabetes
Too much protein in urine can indicate pregnancy or high protein diet; high protein can also be an indication of bone cancer