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Clinical Chemistry 1 > Lecture 1: Blood Gas Physiology > Flashcards

Lecture 1: Blood Gas Physiology Flashcards

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1
Q

pH of basic and acidic solution?

A

Basic: 7 up
Acidic: 7 below

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2
Q

What is a buffer?

A

solutions that contain a weak acid and its a conjugate base; as such, they can absorb excess H+ions or OH–ions, thereby maintaining an overall steady pH in the solution.

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3
Q

Equation for pH

A

pH = −log[H+]

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4
Q

Examples of body functions that create acidic environment

A

Protein breakdown produces phosphoric acid

Anaerobic respiration of glucose produces lactic acid

Fat metabolism yields organic acids and ketone bodies

Carbon dioxide is also an acid. Transporting CO2 as bicarbonate leads to a release of H+ (an acid)

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5
Q

pH of arterial blood

A

7.4

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6
Q

Intracelluar fluid pH

A

7.0

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7
Q

What are the 3 types of buffering systems and what do they use?

A

1) Respiratory buffering system
Uses bicarbonate

2) Blood buffering system
Uses bicarbonate, phosphate, and protein

3) Renal buffering system
Uses bicarbonate, phosphate, and ammonia

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8
Q

Why do we need buffer systems?

A

Body’s pH drop and if below 6.8 or above 8 then dead as it interferes with enzyme systems and cell activity and electroytes

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9
Q

What are the buffer systems in body fluids?

A

Refer to diagram in lecture and notes

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10
Q

Describe the action of the buffer systems:
CARBONIC ACID BICARBONATE BUFFER

PHOSPHATE BUFFER SYSTEM

PROTEIN BUFFER SYSTEM

A

CARBONIC ACID BICARBONATE BUFFER
Cellular respiration produces carbon dioxide as a waste product.
This is immediately converted to bicarbonate ion in the blood. On reaching the lungs it is again converted to and released as carbon dioxide.

PHOSPHATE BUFFER SYSTEM
Operates in the internal fluids of all cells.
It consists of dihydrogen phosphate ions as the hydrogen ion donor ( acid ) and hydrogen phosphate ion as the ion acceptor ( base ) .

PROTEIN BUFFER SYSTEM
Maintain acidity in and around the cells.
Haemoglobin makes an excellent buffer by binding to small amounts of acids in the blood, before they can alter the pH of the blood.

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11
Q

What is the first line of defence against pH shift?

A

CARBONIC ACID BICARBONATE BUFFER

PHOSPHATE BUFFER SYSTEM

PROTEIN BUFFER SYSTEM

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12
Q

What is the SECOND line of defence against pH shift?

A

Respiratory Mechanism (remove CO2)

Renal Mechanism (H+ excretion)

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13
Q

What is ACIDOSIS:
What is the pH
What causes repsiratory acidosis?
What causes metabolic (kidney) acidosis?

A

pH: 7.35 of body fluids
Respiratory: Caused by inadequate ventilation

Metabolic: Results from all conditions other than respiratory that decrease pH

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14
Q

What is ALKALOSIS:
What is the pH
What causes repsiratory alkalosis?
What causes metabolic (kidney) alkalosis?

A

pH: 7.45

Respiratory: Caused by hyperventilation

Metabolic: Results from all conditions other than respiratory that increase pH

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15
Q

The rule of compensation mechanism

Eg what is the compensation if there is a primary metabolic disorder?

what is the compensation if there is a primary respiratory disorder?

A

When a primary acid-base disorder exists, the body attempts to return the pH to normal via the “other half” of acid base metabolism.

Primary metabolic disorder = Respiratory compensation

Primary respiratory disorder = Metabolic compensation

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16
Q

How does the LUNGS correct too much acid AND OR too basic environment

*assuming NO disorder

A

Acidic (low pH):
Respiratory system will ventilate more (remove CO2) and this will raise pH back toward set point

Basic (high pH):
Respiratory will ventilate less (trap CO2 in body) and this will lower pH back toward set point

17
Q

How does the KIDNEYS correct too much acid AND OR too basic environment

*assuming NO disorder

A

Acidic (low pH):
Intercalated cells will secrete more acid into tubular lumen and make NEW bicarbonate (more base) and raise pH back to set point.

Basic (high pH):
Proximal convoluted cells will NOT reabsorb filtered bicarbonate (base) and will eliminate it from the body to lower pH back toward normal.

18
Q

What is respiratory acidosis?

A

the lungs can’t remove enough of the carbon dioxide (CO2) produced by the body. (elevated CO2 greater than 45mmHg)

Low pH (below 7.35)

19
Q

What causes respiratory acidosis?

A

Depression of respiratory centers via narcotic, drugs, anesthetics
CNS disease and depression, trauma (brain damage)

20
Q

What is respiratory alkalosis?

A

increasedrespirationelevates the blood pH beyond the normal range (7.35–7.45) with a reduction in arterial levels of carbon dioxide. (less than 35mmHg- lowered CO2)

21
Q

What causes respiratory alkalosis?

A

Hyperventilation syndrome/ psychological (fear, pain)
Ascent to high altitudes
Fever

22
Q

What is metabolic acidosis?

A

Reduction in bicarbonate (HCO3−)

23
Q

What causes metabolic acidosis?

A
  • Diarrhea (loss of intestinal bicarbonate)
  • Ingestion, infusion or production of more acids (alcohol)
  • Salicylate overdose (aspirin)
  • Accumulation of lactic acid in severe Diabetic ketoacidosis
  • Starvation
24
Q

What is metabolic alkalosis?

A

increase in serum bicarbonate (HCO3-) concentration.

25
Q

What causes metabolic alkalosis?

A
  • Excessive loss of acids due to loss of gastric juice during prolonged vomiting
  • Excessive bases due to ingestion, infusion, or renal reabsorption of bases
  • Intake of stomach antacids
  • Diuretic abuse (loss of H+ ions)
  • Severe potassium depletion
  • Steroid therapy
26
Q

How can you tell if the acid-base imbalance is from a kidney disorder or a lung disorder?

*In terms of pH, HCO3- and pCO2

A

Acidosis:

  • pH less than 7.4
  • Metabolic: Decreased HCO3- or normal
  • Respiratory: Increased pCO2

Alkalosis:

  • pH above 7.4
  • Metabolic: Increased HCO3-
  • Respiratory: Decreased pCO2 or normal
27
Q

What are the two questions when interreting the arterial blood gas?

A

First Question: Does the patient exhibit acidosis or alkalosis?


Second Question: What is the primary problem? Metabolic? or Respiratory?

28
Q

Determine if the patient is demonstrating an ACIDOTIC or ALKALOTIC AND if it is RESP or METABOLIC

pH below 7.35 and pCO2 greater than 45mmHg

A

Acidotic Resp

29
Q

Determine if the patient is demonstrating an ACIDOTIC or ALKALOTIC AND if it is RESP or METABOLIC

pH above 7.45 and pCO2 below 35mmHg

A

Alkalotic and RESP

30
Q

Determine if the patient is demonstrating an ACIDOTIC or ALKALOTIC AND if it is RESP or METABOLIC

pH lower than 7.35 and HC03- less than 22mEq/L

A

Acidotic and Metabolic

31
Q

Determine if the patient is demonstrating an ACIDOTIC or ALKALOTIC AND if it is RESP or METABOLIC

pH greater than 7.45 and HC03- greater than 26mEq/L

A

Alkalotic and Metabolic

32
Q

Low HCO3- and HIGH CO2 conc

A

Acidosis

33
Q

What is the compensation for metabolic acidosis?

A

Resp

34
Q

What is the compensation for Resp alkalosis?

A

Renal

Clinical Chemistry 1 (9 decks)

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