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Physiology credit IV > Class 2 8-10.03.2016 > Flashcards

Class 2 8-10.03.2016 Flashcards

1
Q

The pH of the body is controlled by 3 systems:

A
  1. Acid-base buffering
  2. The respiratory center
  3. The kidneys
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2
Q

Normal range of arterial pH is:

A

Normal range of arterial pH is 7.35 to 7.45

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3
Q

Acidosis pH:

A

If arterial pH is less than 7.35, is called acidosis

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4
Q

Alkalosis

A

If arterial pH is more than 7.45, is called alkalosis

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5
Q

pH range compatible with life:

A

6.8 to 8.0

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6
Q

Relationship between pH and [H+]:

A

Relationship between pH and [H+] is not linear: it’s logarithmic:– Changes in the acidic range reflect larger changes in [H+] than changes in the alkaline range

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7
Q

What happens to pH when H+ increases?

A

As [H+] increases, pH decreases

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8
Q

Respiratory and renal compensation also work to maintain normal pH. What is the difference between renal and respiratory compensation?

A
  • Respiratory compensation working within minutes to hours

- Renal compensation works from hours to days

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9
Q

What is the end product of aerobic metabolism in cells?

A

CO2, carbondioxide

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10
Q

How do we get carbonic acid from carbondioxide? (example of Volatile form (e.g. CO2))

A

When CO2 reacts with water we get carbonic acid (H2CO3)

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11
Q

How do we get fixed acid?

A
  • From breakdown of proteins and lipids (~50 mmole/day fixed acid).
  • Some fixed acids produced during pathophysiological states
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12
Q

From breakdown of proteins and lipids (~50 mmole/day fixed acid)

A
  • Proteins with sulfur generate sulfuric acid

* Phospholipid breakdown generates phosphoric acid

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13
Q

What happens in untreated diabetes mellitus? (fixed acid production)

A

Ketoacids are produced (e.g. β-hydroxybutyric acid, acetoacetic acid)

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14
Q

What happens in hypoxic tissue or during strenuous exercise? (fixed acid production)

A

Lactic acid may be produced

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15
Q

What is produced by ingestion of methanol? (fixed acid production)

A

Formic acid

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16
Q

what will ingestion of ethylene glycol produce? (fixed acid production)

A

Glycolic and oxalic acids

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17
Q

What does overproduction or ingestion of fixed acids cause? (fixed acid production)

A

Metabolic acidosis

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18
Q

Definition of buffer:

A

Buffer is a mixture of a weak acid (HA) and its conjugate base (A-) or a weak base (B) and its conjugate acid (BH+)

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19
Q

How is the pK is different for each buffer pair?

A
  • Strong acids have high equilibrium constants (greater dissociation) and low pKs
  • Weak acids have low equilibrium constants (less dissociation) and high pKs
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20
Q

How is the pK for the best buffers?

A

Best buffers have a pK near the final pH you want

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21
Q

What is the pK for the best physiological buffer?

A

Best physiological buffers have pK within 1 pH unit of 7.4.

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22
Q

What is the most important extracellular buffer?

A

HCO3-/CO2 Buffer

23
Q

What is the Davenport Diagram?

A

It is a nomogram to predict the different “disturbances” in acid base balance, based on the blood pH and the amount of HCO3- in solution.

24
Q

How does the acidosis and alkalosis shift the balance in the Davenport Diagram?

A

Acidosis will shift the balance to the left, and alkalosis will shift it to the right.

25
Q

How are the respiratory acidosis and respiratory alkalosis positioned in the Davenport Diagram

A

Since respiratory disturbances will shift the amount of HCO3- in solution the opposite of CO2, then respiratory acidosis will be in the top left, and respiratory alkalosis in the lower right corner of the nomogram.

26
Q

What causes Metabolic Alkalosis?

A

The abnormal loss of acid (as in vomiting gastric HCl) or addition of a weak base can lead to the condition of Metabolic Alkalosis: increasing pH above 7.4.

27
Q

What causes Metabolic Acidosis?

A

In contrast, abnormal removal of HCO3- or another alkali or addition of acids other than CO2 or H2CO3 (as can happen in renal failure) can lead to Metabolic Acidosis: decreasing pH below 7.35.

28
Q

What does the lungs control?

A

The lungs control CO2.

29
Q

What does the kidneys control?

A

the kidney controls HCO3

30
Q

What are the two ways an acidosic state can exist?

A

The only 2 ways an acidotic state can exist is from either too much pCO2 or too little HCO3.

31
Q

What are the two ways an alkalotic state can exist?

A

The only 2 ways an alkalotic state can exist is from either too little pCO2 or too much HCO3.

32
Q

What is respiratory acidosis?

A

Respiratory Acidosis is the inability of the lungs to eliminate CO2 efficiently; so the equilibrium shifts toward increased H+ and HCO3 -; therefore, pH decreases.

33
Q

What is respiratory alkalosis?

A

Respiratory Alkalosis is excessive loss of CO2 through ventilation driving the equilibrium to the left away from H+ therefore, pH increases.

34
Q

Define respiratory acidosis:

A

Respiratory acidosis is defined as a pH less than 7.35 with a PaCO2 greater than 45 mm Hg.

35
Q

What causes acidosis?

A

Acidosis is caused by an accumulation of CO2 which combines with water in the body to produce carbonic acid, thus, lowering the pH of the blood.

36
Q

Any condition that results in hypoventilation can cause ____________

A

respiratory acidosis

37
Q

Define respiratory alkalosis:

A

Respiratory alkalosis is defined as a pH greater than 7.45 with a PaCO2 less than 35 mm Hg.

38
Q

What are the conditions that can result in repiratory alkalosis?

A
  • Psychological responses, such as anxiety or fear
  • Pain
  • Increased metabolic demands, such as fever, sepsis, pregnancy, or thyrotoxicosis
  • Medications, such as respiratory stimulants
  • Central nervous system lesions
39
Q

Any condition that causes hyperventilation can result in _______________.

A

respiratory alkalosis

40
Q

How is the patient presenting respiratory alkalosis?

A

Patients presenting with respiratory alkalosis have dramatically increased work of breathing and must be monitored closely for respiratory muscle fatigue. When the respiratory muscles become exhausted, acute respiratory failure may ensue.

41
Q

Define metabolic acidosis:

A

Metabolic acidosis is defined as a bicarbonate level of less than 22 mEq/L with a pH of less than 7.35.

42
Q

What causes metabolic acidosis?

A

Metabolic acidosis is caused by either a deficit of base in the bloodstream or an excess of acids, other than CO2. Diarrhea and intestinal fistulas may cause decreased levels of base.

43
Q

Causes of increased acids include:

A
  • Renal failure
  • Diabetic ketoacidosis
  • Anaerobic metabolism
  • Starvation
  • Salicylate intoxication
44
Q

What is metabolic alkalosis defined as?

A

Metabolic alkalosis is defined as a bicarbonate level greater than 26 mEq/liter with a pH greater than 7.45.

45
Q

What causes metabolic alkalosis?

A

Either an excess of base or a loss of acid within the body can cause metabolic alkalosis.

46
Q

What does excess of base occure from? (metabolic alkalosis)

A
  • Excess base occurs from ingestion of antacids, excess use of bicarbonate, or use of lactate in dialysis.
47
Q

What does loss of acid occure from? (metabolic alkalosis)

A
  • Loss of acids can occur secondary to protracted vomiting, gastric suction, hypochloremia, excess administration of diuretics, or high levels of aldosterone.
48
Q

What line does the lungs represent in the line of regulation of pH.

A

The LUNGS represent the second line of regulation of pH.

49
Q

What does increased pCO2 will lead to a decrease in pH?

A

Increased pCO2 will lead to a decrease in pH.

50
Q

How does the lungs regulate the pH?

A

The lungs ability to release CO2 from the blood allows it to regulate pH, as increased ventilation will vent CO2, increase pH by adjusting the [H+].

51
Q

What stimulates the ventilation rate?

A

The ventilation rate is directly stimulated by the pO2 because the pH directly affects the solubility of blood for O2 . Increased pH decreases O2 and reflexively increases ventilation rate to increase O2 intake, thereby venting out CO2.

52
Q

How does the kidneys control acid-base balance?

A

The kidneys control acid-base balance by excreting either an acidic or basic urine.

53
Q

How does the kidney remove the base from the blood?

A

The kidney filters large volumes of HCO3- and the extent to which they are either excreted or reabsorbed determines the removal of “base” from the blood.

54
Q

How does the kidneys remove the H+ from the blood?

A

The kidney secretes large numbers of H+ into the tubule lumen, thus removing H+ from the blood.

Physiology credit IV (3 decks)

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