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18 Cards in this Set
- Front
- Back
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Osmolality calculation for person who drinks 2L of water
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- Normally 42L of water, 290 mOsm/L
- 42 * 290 = 12180 mOsm - 12180/44L = 278 mOsm/L |
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Vasopressin/ADH production
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- Made in the hypothalamus
- Osmoreceptors and baroreceptors feed into hypothalamus, induce production |
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Arginine vs. Lysine vasopressin
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- Arginine is the human variety
- Lysine vasopressin in other mammals |
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3 factors stimulating AVP release
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1) Cell dehydration (higher osmolarity)
2) Hypovolemia (from barorecptors) 3) Pain, trauma, stress, anesthetics, nicotine, morphine, angiotensin II *** Ethanol and atrial natiuretic hormone decrease AVP |
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Biggest factor in AVP release
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- Plasma osmolarity - even small changes influence [AVP] significantly
- More hyperosmotic = more AVP = more aquaporins = more water reabsorption |
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Blood volume effect on AVP levels
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- Lower blood volume (hemorrhage, etc.) -> significantly higher [AVP]
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Why cold weather/swimming pool makes you pee?
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- Cold diverts blood from capillaries to conserve heat
- Increased volume -> activated baroreceptors -> less AVP release -> less water reabsorption |
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Thirst response stimuli
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- Baroreceptor and osmolarity receptor -> hypothalamus -> thirst response
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Congestive heart failure effect on AVP
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- Maintaining arterial volume = main objective
- CHF arteries "see" less blood coming to them - think volume is low - AVP released, thirst response activated - H2O intake increase, more H2O retained by body - Hyponatremia from diluted plasma - Brain swelling |
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Syndrome of inappropriate ADH/AVP (Schwartz-Barter syndrome)
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- Persistant, unstimulated AVP release
- Excess H2O intake, retention - Treatment = AVP antagonist, limit H2O/Na+ intake |
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Marathon runner excess water drinker problem
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- Take in excess H2O without Na+
- Hyponatremia, brain swelling |
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Diabetes mellitus AVP problem
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- Glucose only reabsorbed at proximal tubule
- After that, will hang out in urine - Glucose in tubules hinders H2O reabsorption |
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Diabetes insipidus AVP problem
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- Impaired AVP production in CNS
- Loss of water reabsorption |
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Glucose osmolarity increase does what to AVP concentration?
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- Decreases it!
- Normally osmolarity increases -> stimulates release of AVP - High glucose concentrations do the opposite... |
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Na+ reabsorption sites
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- Majority (67%) at proximal tubule
- Increasing/decreasing proximal tubule action can mess up downstream fine-tuning |
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Glomerulotubular balance purpose
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- Proximal tubule absorbs 2/3 of Na+
- This protects downstream fine-tuning - If GFR increases -> filtered load increases -> proximal tubule still absorbs 2/3 of increased amount |
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Biggest point about sodium
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- It really controls fluid volume
- Adding Na+ doesn't really increase [Na+] - Fluid shifts to equilibrate |
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150 mmol of Na+ = how much fluid?
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- About 1 liter
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