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SAQ3-DUKE=1/GIGU MIDTERM #2(part 2) > Renal Mechanism of Acid Base Balance > Flashcards

Renal Mechanism of Acid Base Balance Flashcards

1
Q

Acid-Base Balance

  • Acid-base balance is one of the most important of the body’s _______ mechanisms
  • Acid-base balance refers to regulation of __________ ion concentration in body fluids
  • Precise regulation of ___ at the cellular level is necessary for survival
  • Slight pH changes have dramatic effects on cellular metabolism
A

homeostatic

hydrogen

pH

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2
Q

Acid-Base Balance

• Achieved by:
– Utilization of chemical buffers in ECF & ICF
– Respiratory mechanisms that excrete ____
– Renal mechanisms that reabsorb ___________ and secrete hydrogen ions
• Normal range of arterial pH is____-_______

A

CO2

bicarbonate

7.37 – 7.42

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3
Q

Acid Production in the Body

  • CO2 - end-product of aerobic metabolism; ___________ acid
  • Fixed Acid – non-volatile
A

volatile

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4
Q

Buffer Mechanism

  • Buffers – are substances that prevent marked change in pH of solution when an acid or base is added to it; consist of weak acid (or its acid salt) and basic salt of that acid
  • Buffer pairs present in body fluids – mainly _________ ______, proteins, hemoglobin, acid phosphate, and sodium and potassium salts of these weak acids
A

carbonic acid

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5
Q

Buffer Mechanism-1
Action of buffers to prevent marked changes in pH

Nonvolatile acids, such as hydrochloric acid, lactic acid, and ketone bodies, buffered mainly by _______ __________

A

sodium bicarbonate

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6
Q

Buffer Mechanism-2
Action of buffers to prevent marked changes in pH

Volatile acids, chiefly carbonic acid, buffered mainly by _______ salts of hemoglobin and oxyhemoglobin

A

potassium

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7
Q

Buffer Mechanism-3
Action of buffers to prevent marked changes in pH

The _____ shift makes it possible for carbonic acid to be buffered in the red blood cell and then carried as bicarbonate in the plasma

A

chloride

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8
Q

Buffer Mechanism-4
Action of buffers to prevent marked changes in pH

Bases are buffered mainly by ______ ________(when homeostasis at pH 7.4 exists)

A

carbonic acid

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9
Q

Buffer Mechanism-5
Action of buffers to prevent marked changes in pH

The Henderson-Hasselbalch equation is a mathematical formula that explains the relationship between __________ ion concentration of body fluids and the ratio of base bicarbonate to ______ ______

A

hydrogen

carbonic acid

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10
Q

Mechanisms of Hydrogen Ion Regulation

A. [H+] is precisely regulated at (pH range 7.2 - 7.4)

1. Body fluid chemical buffers
 (rapid but \_\_\_\_\_\_\_\_\_\_) 
1- bicarbonate 
2- ammonia
3- proteins
4 - phosphate

B. Lungs (____, eliminates CO2)

C. Kidneys (_______, powerful); eliminates non-volatile acids

  • secretes H+
  • reabsorbs HCO3-
  • generates new HCO3-
A

temporary

rapid

slow

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11
Q

Buffer Systems in the Body x 4

___________ : most important ECF buffer
____________ : important renal tubular buffer
_________ : important renal tubular buffer #2
___________ : important intracellular buffers

A

Bicarbonate

Phosphate

Ammonia

Proteins

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12
Q

(____-______% of buffering is in the cells)

A

60-70

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13
Q

Importance of Buffer Systems

Normal H+ concentration = 0.00004 mmol/L
Amount of non-volatile acid produced ~ 60-80 mmol/day 80 mmol/42 L = 1.9 mmol/L
= 47,500 times > normal H+ concentration

A

Know

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14
Q

Bicarbonate Buffer System

Effectiveness of buffer system depends on:

  1. concentration of ___________
  2. pK of system and pH of body fluids
A

reactants

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15
Q

Respiratory Regulation of Acid-Base Balance

Feedback Gain = 1.0 to 3.0 (corrects 50 to ___%)

A

75

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16
Q

Bicarbonate Buffer System

Is the most important buffer in ________
fluid even though the concentration of the components are low and pK of the system is 6.1, which is not very close to normal extracellular fluid pH (7.4).

Reason: the components of the system (CO2 and HCO3-) are closely regulated by the _____ and the _________

A

extracellular

lungs

kidneys

17
Q

Urinary Mechanism

  1. Reabsorption of HCO3-
  2. Excretion of fixed H+ produced from ________ and phospholipid catabolism
A

protein

18
Q

Bicarbonate Reabsorption-1

Effect of filtered load of HCO3-
– ________ HCO3- exceeds the reabsorptive capacity

A

Excess

19
Q

Bicarbonate Reabsorption-2

Effect of ECF volume
– ECF volume expansion ________ HCO3- reabsorption
– ECF volume contraction _________ HCO3- reabsorption
– Angiotensin II mechanism

A

inhibits

stimulates

20
Q

Bicarbonate Reabsorption-3

Effect of CO2
– Increase in pCO2 = _________ in HCO3- reabsorption
– Decrease in pCO2 = _________ in HCO3- reabsorption

A

increase

decrease

21
Q

Excretion of H+ as NH4+–1

Effect of acidosis on NH3 synthesis
– Acidosis increases _________ metabolism

A

glutamine

22
Q

Excretion of H+ as NH4+—2

Effect of plasma K+ concentration on NH3
synthesis
– Hyperkalemia _______ NH3 synthesis, causing type 4 renal tubular acidosis
– Hypokalemia _________ NH3 synthesis

A

inhibits

stimulates

23
Q

Acid-Base DISORDERS

  • _________ acid-base disorders – primary disorders involving HCO3-
  • _______ acid-base disorders – primary disorders involving CO2
  • Therefore, there are four simple acid-base disorders.
  • There can also be mixed acid-base disorders.
A

Metabolic

Respiratory

24
Q

Plasma Anion Gap-1

  • A measurement useful in diagnosis of acid- base disorders
  • Based on principle of ________________
  • Unmeasured anions = gap
  • Normal range: 8-16 mEq/L
A

electroneutrality

25
Q

Plasma Anion Gap-2

  • Useful primarily in the differential diagnosis of ___________ diagnosis
  • If HCO3- is replaced by unmeasured anions, the calculated anion gap is __________
  • If HCO3- is replaced by Cl-, the calculated anion gap is normal
A

metabolic

increased

26
Q

Anion Gap as a Diagnostic Tool

In body fluids: total ________ = total anions

Anion Gap – is defined as the difference between unmeasured anions and unmeasured cations

Normal anion gap = 8 - 16 mEq / L

A

Cations

27
Q

Plasma Anion Gap-3

• Metabolic acidosis with ______ anion gap

– Diabetic ketoacidosis
– Lactic acidosis
– Salicylate poisoning
– Methanol poisoning
– Ethylene glycol poisoning – Chronic renal failure
A

increased

28
Q

Plasma Anion Gap-4

• Metabolic acidosis with _______ anion gap
• No organic anion is accumulated
– Diarrhea
– Renal tubular acidosis

A

normal

29
Q

Renal Compensation for Acidosis

Increased addition of HCO3- to body by kidneys (increased H+ loss by ________)

This can increase to as high as 500 mmol/day

A

kidneys

30
Q

Renal Compensation for Alkalosis

HCO3- excretion can ______ markedly in alkalosis

A

increase

31
Q

Renal Compensations for Acid-Base Disorders

  1. Acidosis:
    - _________ H+ excretion
    - increased HCO3- reabsorption - production of new HCO3-
  2. Alkalosis:
    - ___________ H+ excretion
    - decreased HCO3- reabsorption - loss of HCO3- in urine
A

increased

decreased

32
Q

Acid-Base Disturbances

Respiratory ________ :

  • brain damage
  • pneumonia
  • emphysema
  • other lung disorders
A

Acidosis

33
Q

Acid-Base Disturbances

Respiratory __________:

  • high altitude
  • psychic (fear, pain, etc)
A

Alkalosis

34
Q

Acid-Base Disturbances

Metabolic __________:

  • increased base intake (e.g. NaHCO3) - vomiting gastric acid
  • mineralocorticoid excess
  • overuse of diuretics (except carbonic anhydrase inhibitors)
A

Alkalosis

SAQ3-DUKE=1/GIGU MIDTERM #2(part 2) (5 decks)

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