Acid base homeostasis

Question 0

normal human pH is

PaCO2 normal valve is

Answer 0

pH is 7.35 to 7.45

PaCO2 is 36 to 44 mmHg (adults)

Question 1

Arterial blood gas ( ABG)

Answer 1

useful indicators of acid-base statue of ECF.

• PaCO2 is for respiratory function ( partial pressure in an artery)
• HCO3 is for renal ( metabolic function )
• pH indicates net results of normal acid base regulation, any dysfunction, body’s compensatory responses, DOESN’T reflect pH inside cell or CSF

Question 2

Buffers

Answer 2

1st line of defense against pH changes in all body fluids, it is a chemical that help control pH of body fluids
-weak acid that release hydrogen ions when fluid is too alkaline

Question 3

Buffer system in ICF and ECF

Answer 3

ICF: phosphate
ECF: carbonic acid bicarbonate into plasma protein

ICF and ECF: are protein into hemoglobin (RBC) and amino acid ( all proteins)

Question 4

Bicarbonate buffer system

Answer 4

primary defense against acid-base disorders, most important in ECF

• base is HCO3
• weak acid is carbonic acid (H2CO3)
• normal ratio of 20:1 ( bicarbonate to carbonic acid) for maintenance of normal pH, chemical equilibrium in ECF

Question 5

Respiratory contribution

Answer 5

second defense against acid base disorders

• lungs excrete CO2 and water from body to get rid of carbonic acid in body
• changes in rate and depth of respiration:
• stimulates chemoreceptors that sense PaCo2 and pH in blood
• exert an influence on and serve to alter the amount of PaCo2 and carbonic acid in blood

Question 6

respiratory compensation

Answer 6

respiratory response to an imbalance of any metabolic acid ( EXCEPT carbonic acid)

• doesn’t corrrect pH disorder
• deficit of any acid except carbonic acid- solution is hypoventilation
• excess of any acid except carbonic acid- solution is hyperventilation
• compensation begins any minutes but takes several hours for full effectiveness

Question 7

renal contribution

Answer 7

third defense against acid base disorder, kidney

• can excrete any acid from body EXCEPT carbonic acid ( in lungs only)
• excrete metabolic acids produced continuously during metabolism

HIGH excretion of hydrogen- more production of ammonia, excreted in urine

LOW excretion of hydrogen- less production of ammonia, reabsorb hydrogen into blood, excrete bicarbonate

Question 8

bicarbonate in plasma

Answer 8

LOW bicarbonate:

• indicates excess of metabolic acids in the blood
• buffered by bicarbonate

HIGH bicarbonate:

• indicates deficit of metabolic acids in blood
• excess of base

Question 9

Renal compensation

Answer 9

HIGH carbonic acid levels means INCREASE secretion of metabolic acids of hydrogen ions

LOW carbonic acid levels means DECREASE secretion ( kidney and liver failure) of metabolic acids of hydrogen ions, excrete bicarbonate ions

Requires several days to be fully operative