Exam 3 - Lecture 41 (Regulation of Acid-Base Balance) Flashcards
What is an acid?
Proton donor OR increases [H+] of a solution
What is a base?
Proton acceptor OR decreases [H+] of a solution
What is pH?
Scale to describe how “acid” something is
inverse log of [H+]
What is normal blood pH?
7.35 - 7.45
What pH is acidemia and severe acidemia?
pH < 7.35; severe = pH < 7.2
What pH is alkalemia and severe alkalemia?
pH > 7.45; severe = pH > 7.6
What is acidosis?
Process by which acidemia occurs
What is alkalosis?
Process by which alkalemia occurs
Why is regulation of pH so important?
Bc protons are very reactive
What are 6 clinical features of acidemia?
- Decreased cardiac output and BP
- Insulin resistance
- Metabolic enzyme inhibition
- Impaired ability of brain to regulate volume
- Hypercalcemia
- Hyperkalemia
What are 3 clinical features of alkalemia?
- Neuromuscular dysfunction
- Hypocalcemia
- Hypokalemia
What 3 things determine pH?
- Partial pressure of CO2 (pCO2)
- Strong Ion Difference (SID)
- Weak acid buffers
Why is CO2 an acid?
Because it generates protons
What does ventilation rate do?
Regulates acid-base balance
What occurs when ventilation rate is decreased?
Increased ECF pCO2 –> increased [H+] –> respiratory acidosis
What causes respiratory acidosis?
Increased [H+] due to increased ECF pCO2
What occurs when ventilation rate is increased?
Decreased ECF pCO2 –> decreased [H+] –> respiratory alkalosis
What causes respiratory alkalosis?
Decreased [H+] due to decreased ECF pCO2
What equation determines pH when taking pCO2 into account?
Henderson-Hasselbalch equation
Which of these statements is correct?
A) Increasing ventilation rate will decrease ECF pH
B) Increasing ventilation rate will increase ECF pH
C) Decreasing ventilation rate could cause alkalosis
A) Increasing ventilation rate will decrease ECF pH
What happens to strong ions at physiological pH?
They fully dissociate
What are 4 positively charged strong ions?
- Na+
- K+
- Ca^2+
- Mg^2+
What are 3 negatively charged strong ions?
- Cl-
- Lactate
- SO4^2-
What is strong ion difference?
Difference between all of the positively charged strong ions and negatively charged strong ions.
Which [ion] is greater in normal SID?
Positively charged
What happens in increased SID?
Higher [cation] and/or lower [anion] than normal
What is the normal SID?
40 mEq/L
What happens in decreased SID?
Lower [cation] or higher [anion] than normal
Changing [SID] changes _____ of ECF.
ionic strength
[SID] drives dissociation of _____ to maintain electroneutrality.
water
[SID] drives dissociation of water to maintain _____.
electroneutrality
What does an increased SID need?
more negative charge
What does a decreased SID need?
more positive charge
How does water provide positive or negative charges to maintain normal SID and eletroneutrality?
Dissociates to provide H+ or OH-
Increased [SID] drives increased [___] and decreased [___].
OH-; H+
Decreased [SID] drives increased [___] and increased [___].
H+; OH-
In metabolic alkalosis, [SID] is _____ because _____.
increased bc it drives increased [OH-]
In metabolic acidosis, [SID] is _____ because _____.
decreased bc it drives increased [H+]
An animal has diarrhea and excessively loses ECF Na+ relative to Cl-. What is the effect on SID and therefore the animal’s acid-base status?
A) SID will increase and cause acidosis
B) SID will increase and cause alkalosis
C) SID will decrease and cause acidosis
D) SID will decrease and cause alkalosis
C) SID will decrease and cause acidosis
What do weak acids do at physiological pH?
partially dissociate
What are 2 examples of weak acids?
- Proteins (albumin, globulin)
2. Phosphates
What is Atot?
HA + A- (undissociated WA + dissociated WA)
What occurs when Atot increases?
Increased [H+] and metabolic acidosis
During metabolic acidosis, what happens to Atot and [H+]?
Atot and [H+] increase
What occurs when Atot decreases?
Decreased [H+] and metabolic alkalosis
During metabolic alkalosis, what happens to Atot and [H+]?
Atot and [H+] decrease
Which statement about Atot is correct?
A) It is primarily determined by ECF phosphate concentration
B) It will increase if animal is hypoproteinemic (low ECF protein)
C) It is decreased by proteinuria (protein in urine)
D) [Atot] = [HA] - [A]
C) It is decreased by proteinuria (protein in urine)
What type of mechanism do pCO2, [SID], and Atot utilize and why?
Compensatory; disturbances in one variable are compensated by other variables
Respiratory acidosis is compensated by _____.
metabolic alkalosis
High pCO2 is compensated by _____.
Increased [SID]
What do the lungs use in acid-base regulation?
CO2
What do the tissues use in acid-base regulation?
CO2 and [SID] (strong ions)
What does the gut use in acid-base regulation?
[SID] (strong ions)
What do the kidneys use in acid-base regulation?
[SID] (strong ions)
What does the liver use in acid-base regulation?
Atot (proteins)
What do the kidneys adjust to correct acid-base disturbance?
ECF [SID]
What is the goal if an animal is acidemic?
increase ECF [SID]
If animal is acidemic, renal ___ abs. decreases and ___ increases.
Cl-; Na+
What is the goal if an animal is alkalemic?
Decrease ECF [SID]
If an animal is alkalemic, renal ___ decreases and ___ increases.
Na+; Cl-
