The Urinary System. Function 1.Remove nitrogenous wastes 2.Maintain electrolyte, acid-base, and...
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Transcript of The Urinary System. Function 1.Remove nitrogenous wastes 2.Maintain electrolyte, acid-base, and...
Function1. Remove nitrogenous wastes2. Maintain electrolyte, acid-base,
and fluid balance of blood3. Homeostatic organ4. Acts as blood filter5. 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
A KidneyBlood and waste enter through renal artery
Filtered blood leaves through renal vein
Excess water and toxic waste leaves through ureter as urine
ureter
Kidney AnatomyKidney Anatomy
renal cortex
renal pelvisrenal medulla
renal pyramids
renal capsule
nephron
renal cortex
renal medulla
Each kidney contains over 1 million nephrons and thousands of collecting ducts
Collecting duct
Loop of Henle
PCT
DCTGlomerulus
Glomerular FiltrationGlomerular Filtrationafferent arteriole glomerulus
efferent arteriole
Bowman’s capsule
Filters blood; proteins can’t pass through
Composition of Glomerular Filtrate• WaterWater• Small Soluble Organic Small Soluble Organic
MoleculesMolecules• Mineral IonsMineral Ions
Proximal Convoluted Tubule
Reabsorbs: water, glucose, Reabsorbs: water, glucose, amino acids, and sodium.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 Creates a gradient of increasing sodium ion concentration towards sodium ion concentration towards the end of the loop within the the end of the loop within the interstitial fluid of the renal pyramid.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 Under the influence of the hormone aldosterone, reabsorbs sodium and aldosterone, reabsorbs sodium and secretes potassium. Also regulates secretes potassium. Also regulates pH by secreting hydrogen ion when pH by secreting hydrogen ion when pH of the plasma is low.pH of the plasma is low.
• only 10% of the filtered NaCl and 20% of water remains
Collecting Duct
Allows for the osmotic Allows for the osmotic reabsorption of water.reabsorption of water.
ADH (antidiuretic hormone)- makes collecting ducts more permeable to water-- produce concentrated urine
From the original 1800 g NaCl, only 10 g appears in the urine
UrineWater- 95%Nitrogenous waste:
• urea• uric acid• creatinine
Ions:• sodium• potassium• sulfate• phosphate
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 (Micturition)
When is incontinence normal?
Why do doctors ask for a urine sample?
Urinalysis
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- normal is ammonia-like
diabetes mellitus- smells fruity or acetone like due to elevated ketone levels
diabetes insupidus- yucky
asparagus---
Odor
Color- pigment is urochromeYellow 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 yellowbright yellow
Infection- cloudy
Color
Water: s.g. = 1g/liter; Urine: s.g. ~ 1.001 to 1.030
Specific Gravity
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
Glucose
Indicative of:• Excessive carbohydrate intake• Stress• Diabetes mellitus
Abnormal Constitutes of Urine
INQUIRY1. List several functions of the kidneys.2. What does the glomerulus do?3. What are several constitutes you should not
find in urine?4. What is specific gravity?5. What two hormones effect fluid volume and
sodium concentration in the urine?6. Where are the pyramids located in the
kidney?7. What vessel directs blood into the
glomerulus?8. Where does most selective reabsorption occur
in the nephron?