Water Balance Flashcards

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1
Q

What are the 3 regulatory hormones of body fluid osmolarity?

A
  1. ADH
  2. RAAS
  3. ANP
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2
Q

What are the three man mechanisms of ADH?

A
  1. Increase H20 permeability in late Distal tubule and collecting duct
  2. Increase Urea permeability inner medullary collecting duct
  3. Increase Na+ Reabsorption in thick ascending LOH
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3
Q

What are the three key signs of severe dehydration?

A

Obtundation, sunken eyes, and poor skin turgor

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4
Q

What is normal ECF/ICF fluid osmolarity?

A

280-290 mOsM

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5
Q

What happens to EC/IC fluid after gaining hypotonic fluid?

A

EC: INC Volume, DEC Osmolarity

IC: INC volume, DEC Osmolarity

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6
Q

What happens to EC/IC fluid after gaining hypertonic fluid?

A

EC: INC Volume, INC Osmolarity

IC: DEC Volume, INC Osmolarity

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7
Q

What happens to EC/IC fluid after losing isotonic fluid?

A

EC: Loss of Volume; NO Change in Osmolarity

IC: No change

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8
Q

What happens to EC/IC fluid after losing hypotonic fluid?

A

EC: DEC Volume, INC Osmolarity

IC: DEC Volume, INC Osmolarity

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9
Q

What happens to EC/IC fluid after losing hypertonic fluid?

A

EC: DEC Volume + OSmolarity

IC: DEC Osmolarity + INC Volume

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10
Q

What is the empirical formula for calculating plasma osmolality?

A

PO = 2(N + K) + (BUN/2.8) + (Glucose/18)

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11
Q

Where is ADH produced?

A

Supraoptic nuclei of hypothalamus

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12
Q

How does ADH result in Greater water permeability?

A

Activates insertion of AQP2 on apical membrane

AVP -> V2 —> INC cAMP —> INC AQP2

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13
Q

Why does a solar it’s in the inner medulla increase with ADH despite increased water reabsorption?

A

Urea Recycling

  • ADH H20 reabsorption —>Urea concentration builds ruses and reaches maximum at inner level of medulla
  • ADH enables Urea diffusion into interstitium —> Build up of corticomedullary osmotic gradient —> INC H20 Reabsorption
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14
Q

How do ascending and descending vasa Recta differ anatomically?

A

Ascending are Fenestrated and more permeable to fluids.

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15
Q

What are the main regulators of ADH secretion?

A
  1. Plasma Osmolarity (Most sensitive)
  2. Decrease in ECF volume/pressure (Not very sensitive)
  3. Other hormones (Angiotensin II or ANP)
  4. Temperature and stress
  5. Pain, nausea, vomiting, and ethanol
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16
Q

What is characterized by diuretics, polyuria, polydypsia, hypervolemic shock, and ADH deficiency?

A

Diabetes insipidus

17
Q

What are the two types of diabetes insipidus?

A
  1. Central: insufficient ADH; Head injury, CNS infections, pituitary stroke, cranipharyngioma, etc
  2. Nephrogenic: Decreased renal response to ADH; Abnormal vasopressin receptors or AQP in renal tubule
18
Q

What is SIADH

A
  • Excess ADH —> Water retention
  • Hyponatremia Andi water intoxication
  • Lung disease, CNA disease, or drugs like ecstasy

*** Paradoxical High Urine Osmolarity due to Na+ excretion