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Water Balance

Water Balance. Urine Output. more water in usually means more urine out Increased water intake = increased urine output Decreased water intake = decreased urine output some liquids encourage increase urine excretion – diuretics frequency of urination dependent on hormonal signals.

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Water Balance

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  1. Water Balance

  2. Urine Output • more water in usually means more urine out • Increased water intake = increased urine output • Decreased water intake = decreased urine output • some liquids encourage increase urine excretion – diuretics • frequency of urination dependent on hormonal signals

  3. Three Effects of Urine • Osmotic Pressure • Blood Pressure • pH Balance

  4. Osmotic Pressure • osmotic pressure (osmolarity) – water pressure due to presence of solutes • The more concentrated a solution, the higher its osmotic pressure (osmolarity) • antidiuretic hormone (ADH) – regulates blood osmotic pressure through kidneys • a short peptide hormone

  5. Osmotic Pressure What type of situation would cause increased osmotic pressure of our blood/interstitial fluid? • sweating / dehydration • causes increased ADH production • increase water reabsorption • dilutes blood • concentrates urine COLLECTING DUCT OF THE NEPHRON INTERSTITIAL FLUID/BLOOD NaCl Urea Water

  6. osmoreceptors in hypothalamus detect increased osmotic pressure  sends signals to pituitary gland ADH produced in hypothalamus and is transported to the pituitary gland for release

  7. Osmoreceptors in hypothalamus Thirst Hypothalamus Drinking reduces blood osmolarity to set point ADH Increased permeability Pituitary gland Distal tubule H2O reab- sorption helps prevent further osmolarity increase STIMULUS: The release of ADH is triggered when osmo- receptor cells in the hypothalamus detect an increase in the osmolarity of the blood Collecting duct Homeostasis: Blood osmolarity

  8. Osmotic Pressure increased osmotic pressure osmoreceptors pituitary gland; release ADH decreased osmotic pressure increased sensation of thirst increased water reabsorption by kidney

  9. ADH Animation The following animation will contain some terminology not covered. Animation

  10. Blood Pressure • blood pressure – increase force of blood on blood vessels • aldosterone – hormone which increases Na+ reabsorption in kidneys • increased H2O in blood • increased blood pressure

  11. Blood Pressure • aldosterone produced in adrenal gland, above kidney

  12. Blood Pressure

  13. Blood Pressure What part of the kidney would be affected by low blood pressure? • glomerulus; high blood pressure needed for filtration • decreased blood pressure detected by juxtaglomerular apparatus (JGA) • receptors next to the glomerulus http://www.youtube.com/watch?v=lYugtoRwBLY

  14. Blood Pressure • the enzyme renin, is released angiotensinogenangiotensin renin

  15. Blood Pressure Two important functions of angiotensin: • causes blood vessel constriction • stimulates aldosterone release

  16. Homeostasis: Blood pressure, volume Increased Na+ and H2O reab- sorption in distal tubules STIMULUS: The juxtaglomerular apparatus (JGA) responds to low blood volume or blood pressure (such as due to dehydration or loss of blood) Aldosterone Arteriole constriction Adrenal gland Angiotensin Distal tubule Angiotensinogen JGA Renin production Renin

  17. Blood Pressure renin-angiotensin-aldosterone axis low blood pressure cells to release renin; produce angiotensin juxtaglomerular apparatus blood pressure increases constrict blood vessels induce aldosterone release; increase Na+ reabsorption http://www.youtube.com/watch?v=bY6IWVgFCrQ

  18. pH Balance How do living systems regulate the amount of acid / base in their systems? • buffers – conjugate acid-base pairs H3PO4 H2PO4- + H+

  19. bicarbonate ion carbonic acid pH Balance • conversion of CO2 to other compounds help regulate blood pH H2O + CO2 H2CO3 HCO3- + H+ • Bicarbonate ions eliminate excess H+ ions, thus preventing a change in pH • HCO3- is reabsorbed in the proximal and distal tubules

  20. Classwork/Homework • Section 7.5 – Pg. 352 #1 – 7 • Section 7.6 – Pg. 356 #1-8, 10 • Section 7.7 – Pg. 362 #1 – 10

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