The Urinary System

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Function 1.Remove nitrogenous wastes 2.Maintain electrolyte(ions), pH (acid-base), and fluid balance of blood 3.Homeostatic organ 4.Acts as blood filter 5.Release hormones What does this mean? It regulates the water and salt in the body. So… whatever excess we have, it helps us get rid of it.

Kidneys as Filters Average kidney filtration rate = 180 liters (50 gal) of blood/day liters are reabsorbed back into blood

Nitrogenous Wastes ammonia urea uric acid

Organs of the Urinary System kidneys ureters urinary bladder urethra

Check your kidney diagram Calyx Renal column Medullary pyramid Pelvis Fibrous capsule Renal cortex

renal capsule renal cortex renal medulla renal pelvis renal pyramids ureter Kidney Anatomy

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Kidney Anatomy renal artery renal vein nephron Nephron = functional unit of kidney Each kidney contains > 1,000,000 nephrons.

urine blood filtration tubular reabsorption and secretion Nephron Functioning “refreshed” blood

vein artery afferent arteriole efferent arteriole glomerulus peritubular capillaries Bowman’s capsule proximal convoluted tubule distal convoluted tubule loop of Henle collecting duct

renal cortex renal medulla Collecting duct Loop of Henle PCT DCT Glomerulus Each kidney contains over 1 million nephrons and thousands of collecting ducts

Glomerular Filtration afferent arteriole glomerulus efferent arteriole Bowman’s capsule Filters blood; proteins can’t pass through

Add ARROWS TO Figure 15-3: Diagram of a NEPHRON.

Label NEPHRON diagram 1. Glomerular capsule 2. Afferent arteriole 3. Efferent arteriole 4. Cortical radiate artery 5. Cortical radiate vein 6. Arucate artery 7. Arcuate vein 8. Interlobar artery 9. Interlobar vein 10. Loop of Henle (nephron loop) 11. Collecting duct 12. Distal convoluted tubule 13. Proximal convoluted tubule 14. Peritubular capillaries 15. glomerulus

Composition of Glomerular Filtrate (1,15) Water Small Soluble Organic Molecules (i.e. amino acids, glucose) Mineral Ions

Proximal Convoluted Tubule (13) Reabsorbs: water, glucose, amino acids, and sodium.

Loop of Henle (10) Descending – reabsorbs H2O Ascending – reabsorbs Na+ and Cl-

Distal Convoluted Tubule (12) ABSORBS - H 2 0 Ca++ PO 4 (phosphates) Na+ SECRETES - H+ K+

Collecting Duct (11) Allows for the osmotic reabsorption of water.

Urine Water- 95% Nitrogenous waste: urea uric acid Creatinine (waste product of muscle cell metabolism) Ions: sodium potassium sulfate phosphate

Urinary Bladder ureters internal sphincters external sphincters urethra Draw & label

Internal urethral sphincter: Smooth muscle Involuntary control External Urethral sphincter: Skeletal muscle Voluntary control Sphincter Muscles on Bladder

When bladder fills with 200 ml of urine, stretch receptors transmit impulses to the CNS and produce a reflex contraction of the bladder (PNS) Diuresis

Distension of the Urinary Bladder Micturition – voiding; eliminating urine

Why do doctors ask for a urine sample? Urinalysis characteristics: smell- ammonia-like pH , ave 6.0 specific gravity– more than 1.0; ~ color- affected by what we eat: salty foods, vitamins

odor- normal is ammonia-like diabetes mellitus- smells fruity or acetone like due to elevated ketone levels diabetes insupidus- yucky asparagus--- Odor

pH- range ave 6.0 vegetarian diet- urine is alkaline protein rich and wheat diet - urine is acidic

Color- pigment is urochrome Yellow color due to metabolic breakdown of hemoglobin (by bile or bile pigments) Beets or rhubarb- might give urine a pink or smoky color Vitamins- vitamin C- bright yellow Infection- cloudy Color

Glucose- when present in urine condition called glycosuria (nonpathological) [glucose not normally found in urine] Indicative of: Excessive carbohydrate intake Stress Diabetes mellitus Abnormal Contents of Urine