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Physiology Fall 21' > CH. 19 Urinary System: Fluid and Electrolyte Balance > Flashcards

CH. 19 Urinary System: Fluid and Electrolyte Balance Flashcards

1
Q

What needs to occur for balance to occur?

A

input + production = utilization + output

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2
Q

What is the function of the kidneys?

A

regulate solute and water content which also determines volume
- regulate acid-base balance

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3
Q

What is a positive solute or water balance?

A

solute or water enters plasma faster than it exits

- quantity increases

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3
Q

What is a positive solute or water balance?

A

solute or water enters plasma faster than it exits

- quantity increases

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4
Q

What is a negative solute or water balance?

A

solute or water exits plasma faster than it enters

- quantity decreases

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5
Q

What cells in the late distal tubules and collecting ducts regulate balance?

A

principal cells
- water electrolytes

intercalated cells
- acid-base balance

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6
Q

What accounts for water intake?

A

gastrointestinal tract and metabolism (generating water as anything is synthesized

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7
Q

What accounts for water output?

A
  1. insensible loss
  2. sweating
  3. gastrointestinal tract
  4. kidneys
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8
Q

What is normovolemia, hypervolemia, and hypovolemia?

A

Normovolemia: normal blood volume
Hypervolemia: high blood volume due to positive water balance (more than 42L)
Hypovolemia: low blood volume due to negative water balance

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9
Q

In which direction does water move in regard to solute concentration?

A

water moves from area of low solute concentration to area of high solute concentration

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10
Q

What is the osmolarity of body fluids?

A

300 mOsm (300 mOsm of solute per liter of plasma

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11
Q

How do kidneys compensate for changes in osmolarity of ECF?

A

regulating water reabsorption

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12
Q

What is it that regulates water reabsorption in the distal tubules and collecting ducts?

A

ADH (vasopressin) secreted by posterior pituitary gland

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13
Q

What is the primary solute in which water reabsorption follows?

A

sodium; establishes an osmotic gradient for water reabsorption when transported across basolateral membrane

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14
Q

What level of osmolarity of interstitial fluid can be found at the cortex vs. renal pelvis of the renal medulla?

A

lower osmolarity near cortex

greater osmolarity near renal pelvis

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15
Q

What establishes the osmotic gradient?

A

countercurrent multiplier: currents go in opposite direction

- ascending limb vs. descending limb

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16
Q

What are the differences between the ascending limb and the descending limb?

A

Ascending limb:

  • impermeable to water
  • active transport of sodium, chlorine, and potassium

Descending limb:

  • permeable to water
  • no transport of sodium, chlorine, or potassium
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17
Q

In order to set up the countercurrent multiplier, what needs to be established first?

A

ascending limb

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18
Q

How does urea contribute approximately 40% of the osmolarity of the gradient?

A

transport of urea through UTA from filtrate to peritubular fluid

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19
Q

What is the role of the vasa recta in the establishment of the medullary osmotic gradient?

A

anatomical arrangement of vasa recta capillaries prevent the diffusion of water and solutes from dissipating the medullary osmotic gradient

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20
Q

What occurs in the descending limb of the vasa recta? and what is its milliosmolarity?

A

water leaves capillaries by osmosis and solutes enter by diffusion through their ion channels
- 300 mOsm

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21
Q

What occurs in the ascending limb of the vasa recta? and what is its milliosmolarity?

A

water moves into plasma and solutes move into interstitial fluid
- 325 mOsm; higher due to lack of urea transporters

22
Q

What is water permeability dependent on?

A

water channels

  1. aquaporin-3: present in basolateral membrane always
  2. aquaporin-2: present in apical membrane only when ADH present in blood
23
Q

What occurs when the membrane of the late distal tubule and collecting duct is impermeable to water?

A
  1. water cannot leave the tubules
  2. no water reabsorption
  3. more water is excreted in urine
24
Q

What does the maximum amount of water reabsorbed depend on?

A

length of loop of Henle

25
Q

What does ADH stimulate in the distal tubule and collecting duct?

A

the insertion of water channels (aquaporin-2) into apical membrane

26
Q

What is an effect that ADH has on water reabsorption?

A
  1. regulates permeability of late distal tubules and collecting ducts
27
Q

Where is ADH released?

A

released from terminals in the posterior pituitary from cell bodies originating in the hypothalamus

28
Q

What two receptors is ADH affected by?

A

baroreceptors and osmoreceptors

29
Q

What occurs when blood pressure drops to less than 80 mmHg?

A
  1. decrease in GFR
  2. decrease in water filtered
  3. decrease in water excretion
30
Q

What occurs when blood pressure increases to more than 180 mmHg?

A
  1. increase in GFR
  2. increase in water filtered
  3. increase in water excretion
  4. occurs only in pathological circumstances
31
Q

What is hypernatremia and hyponatremia?

A

hyper: high plasma sodium
hypo: low plasma sodium

32
Q

What is the primary solute in ECF and what is it critical for?

A

sodium

  • critical for normal osmotic pressure
  • critical to function of excitable cells.
33
Q

What does freely filtered refer to?

A

100% of substance is moved from glomerulus to bowman’s capsule

34
Q

What regulates sodium reabsorption and where does it occur?

A

aldosterone and ANP

- regulated at principal cells of distal tubules and collecting ducts

35
Q

What is the effect of aldosterone and what secretes it?

A

increases sodium reabsorption and secreted from adrenal cortex

  • increase number of sodium/potassium pumps on basolateral membrane
  • increases number of open sodium and potassium channels on apical membrane
36
Q

What 3 ways is renin release stimulated?

A
  1. decreased pressure in afferent arteriole
  2. renal sympathetic nerve activity
  3. decreases in sodium and chlorine in distal tubule filtrate
37
Q

How does atrial natriuretic peptide increase GFR?

A

dilation of afferent arteriole and constriction of efferent arteriole

38
Q

How does ANP decrease sodium reabsorption?

A

closing sodium channels in apical membrane; increased sodium excretion

39
Q

What is hyperkalemia and hypokalemia?

A

hyper: high plasma potassium
hypo: low plasma potassium

40
Q

What does potassium in plasma directly stimulate?

A

aldosterone release; potassium increase leads to more aldosterone release

41
Q

What is hypercalcemia and hypocalcemia?

A

hypercalcemia: high plasma calcium
hypo: low plasma calcium

42
Q

Why is calcium balance critical?

A
  1. triggers exocytosis in neurons
  2. triggers secretion
  3. triggers muscle contraction
  4. increases contractility of cardiac and smooth muscle
43
Q

Where is reabsorption of calcium regulated?

A

in loops of henle and distal tubules

44
Q

What is considered acidosis and alkalosis?

A

acidosis: pH < 7.35
alkalosis: pH > 7.45

45
Q

What 5 complications can lead to an acid-base disturbance?

A
  1. conformation change in protein structure
  2. changes in excitability of neurons
  3. changes in potassium balance
  4. cardiac arrhythmias
  5. vasodilation
46
Q

What can lead to metabolic acidosis?

A
  1. high protein diet
  2. high fat diet
  3. heavy exercise
  4. severe diarrhea
  5. renal dysfunction
47
Q

What can lead to metabolic alkalosis?

A
  1. excessive vomiting
  2. consumption of alkaline products
  3. renal dysfunction
48
Q

What are the three lines of defense against acid-base disturbances?

A
  1. buffering of hydrogen ions
  2. respiratory compensation
  3. renal compensation
49
Q

What is the quickest defense against changes in pH?

A

buffering

50
Q

How does respiratory compensation work in acting against acid-base disturbances?

A

increased ventilation -> decreased carbon dioxide

decreased ventilation -> increased carbon dioxide

51
Q

How does renal handling of hydrogen and bicarbonate ions occur in the proximal tubule and distal tubule and collecting duct?

A

proximal tubule: bicarbonate reabsorption coupled to hydrogen ion secretion

distal tubule and collecting duct: secretion of hydrogen ions coupled to synthesis of new bicarbonate ions

52
Q

When does glutamine come into play in acid-base disturbances?

A

severe acidosis; glutamine metabolism produces new bicarbonate and secretes hydrogen in the form of ammonium

Physiology Fall 21' (15 decks)

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