The Urinary System

Function Remove nitrogenous wastes Maintain electrolyte, acid-base, and fluid balance of blood Homeostatic organ Acts as blood filter Release hormones: calcitriol & erythropoietin

Kidneys as Filters Diuretic- loose water; coffee, alcohol Antidiuretic- retain water; ADH Aldosterone- sodium & water reabsorption, and K+ excretion GFR= 180 liters (50 gal) of blood/day 178-179 liters are reabsorbed back into blood Excrete a protein free filtrate

Organs of the Urinary System kidneys ureters urinary bladder urethra

A Kidney Blood and waste enter through renal artery Filtered blood leaves through renal vein Excess water and toxic waste leaves through ureter as urine

The Urinary System

General Functioning of the Kidney

Nitrogenous Wastes Proteins Amino acids COOH -NH2 Ammonia Urea Uric Acid

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

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

DCT PCT Glomerulus Collecting duct Peritubular capillaries Loop of Henle To renal pelvis

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

Composition of Glomerular Filtrate Water Small Soluble Organic Molecules Mineral Ions

Proximal Convoluted Tubule Reabsorbs: water, glucose, amino acids, and sodium. 65% of Na+ is reabsorbed 65% of H2O is reabsorbed 90% of filtered bicarbonate (HCO3-) 50% of Cl- and K+

Loop of Henle Creates a gradient of increasing sodium ion concentration towards the end of the loop within the interstitial fluid of the renal pyramid. 25% Na+ is reabsorbed in the loop 15% water is reabsorbed in the loop 40% K is reabsorbed in the loop

Distal Convoluted Tubule Under the influence of the hormone aldosterone, reabsorbs sodium and secretes potassium. Also regulates pH by secreting hydrogen ion when pH of the plasma is low. only 10% of the filtered NaCl and 20% of water remains

Collecting Duct Allows for the osmotic reabsorption of water. ADH (antidiuretic hormone)- makes collecting ducts more permeable to water-- produce concentrated urine

Urine Water- 95% Nitrogenous waste: urea uric acid creatinine Ions: sodium potassium sulfate phosphate From the original 1800 g NaCl, only 10 g appears in the urine

Urinary Bladder ureters urethra internal sphincters external sphincters

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

Urinalysis Why do doctors ask for a urine sample? characteristics: smell- ammonia-like pH- 4.5-8, ave 6.0 specific gravity– more than 1.0; ~1.001-1.030 color- affected by what we eat: salty foods, vitamins

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

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

Specific Gravity Water: s.g. = 1g/liter; Urine: s.g. ~ 1.001 to 1.030 When urine has high s.g.; form kidney stones Diabetes insipidus- urine has low s.g.; drinks excessive water; injury or tumor in pituitary

pH- range 4.5-8 ave 6.0 vegetarian diet- urine is alkaline protein rich and wheat diet- urine is acidic

Normal Constitutes of Urine

Normal Constitutes of Urine

Abnormal Constitutes of Urine  Glucose Indicative of: Excessive carbohydrate intake Stress Diabetes mellitus

Abnormal Constitutes of Urine Albumin

Abnormal Constitutes of Urine Ketone RBC Hemoglobin Bile WBC Casts

INQUIRY List several functions of the kidneys. What does the glomerulus do? What are several constitutes you should not find in urine? What is specific gravity? What two hormones effect fluid volume and sodium concentration in the urine? Where are the pyramids located in the kidney? What vessel directs blood into the glomerulus? Where does most selective reabsorption occur in the nephron?

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