Lecture 20: Acid/Base Physiology (Final Exam) Flashcards
For the purposes of A&P, what is normal pH?
7.4
What occurs to serum proteins when excess hydrogen ions are present?
Conformational change of the protein occurs.
What are volatile compounds?
Give examples.
Compounds that can escape to a gaseous phase easily.
Ex. CO₂ , VAA’s
Whats an example of a bodily acid that is non-volatile?
How is this compound removed from the body?
- Lactic acid
- Renal excretion
The majority of acid in the body is found in the form of ____.
CO₂
Where do the components of CO₂ come from?
- O₂ from respiration
- C from food diet
What is the central acid/base formula?
What enzyme converts H₂CO₃ to CO₂ and H₂O ?
Carbonic Anhydrase.
Excess CO₂ would push the acid/base formula to the _____.
right
What cell membrane pump is adversely affected by acidosis?
Na⁺ K⁺ ATPase Pump
What is the result of a dysfunctional Na⁺K⁺ATPase pump due to acidosis?
Why does this occur?
- Hyperkalemia
- Occurs due to excessive ICF H⁺ causing efflux of H⁺ and K⁺ to the ECF.
What organ deals with acidosis in the short term?
What organ deals with acidosis in the long term?
- Short term = Lungs
- Long term = Kidneys
pH is a _______ scale. This means that small changes in pH equate to ______ changes in [H⁺].
logarithmic ; large
Strong acids dissociate into ______ conjugate bases.
weak
Weak acids dissociate into _____ conjugate bases.
strong
What does H₂CO₃ dissociate into?
H⁺ : acid
HCO₃⁻ : conjugate base
How is pH calculated?
pH = -log[H⁺]
or
pH = pK + log (A⁻ ÷ HA)
What is a product of abnormal metabolism?
Lactate
Ketones are _______ and therefore have to be ______ excreted.
non-volatile ; renally
How are H⁺ excreted in the urine?
NH3 + H⁺ → NH₄⁺
What is a normal serum HCO₃⁻ level?
24 mOsm/L
What occurs to hemoglobin when around excess hydrogen ions?
O₂ will dissociate off the Hb molecule
What is the primary protein buffer necessary for normal HCO₃⁻ activity?
Hemoglobin
If the PCO₂ is excessively high, then a commensurate increase in what is needed to prevent acidosis?
HCO₃⁻
What is the most important blood buffer?
What is necessary for this buffer to be effective?
HCO₃⁻ is most important buffer but requires normal serum protein concentrations.
What is the lowest possible pH on the 20mmHg PCO₂ isobar?
What about the highest?
Lowest ≈ 7.36 w/ a HCO₃⁻ of almost 10 mmol/L
Highest ≈ 7.75 w/ a HCO₃⁻ of around 24 mmol/L
Given the graph below, how would a stronger buffer change the graph?
The buffer line would be more steep.
Polycythemia would result in a __________ buffering capacity.
Why?
Increased buffering capacity
This is due to excess Hb capacity to “capture” excess H⁺.
Anemia would result in a ________ to buffering capacity.
decrease
Name the other buffering compounds aside from plasma proteins and bicarbonate.
- Sulfur compounds
- Phosphate compounds
- Ammonia compounds
What buffer compounds are found primarily intracellularly?
- Sulfur
- Phosphate
What two phosphate buffer compounds were mentioned in lecture?
- ATP
- H₂PO₄ → H⁺ + HPO₄⁻
What is the general pK of phosphate compounds?
pK ≈ 6.8
What is the normal pH of urine?
≈ 5
How many ATP molecules are produced via glycolysis?
2 ATPs
How many ATP molecules are produced via the Krebs cycle (citric acid cycle)?
34 ATPs
How many ATP molecules are produced via combined glycolysis and citric acid cycle?
36 ATPs
What occurs with “uncoupled metabolism” ?
Excess H⁺ (or something else) inhibits proteins in the glycolysis/Krebs cycle → increase glucose usage w/ decreased ATP formation.
Possible anaerobic metabolism and excess lactate formation.
Why is acute respiratory acidosis more acidotic than chronic respiratory acidosis?
Kidneys haven’t had time to increase HCO₃⁻ production to accommodate excess CO₂.
When is metabolic acidosis seen?
When the kidneys don’t produced enough HCO₃⁻ to compensate for acidosis.
Which of the following conditions is a result of hyperventilation?
Acute Respiratory alkalosis
↓PCO₂ → ↓CBF
Differentiate the clinical presentations of early and late COPD patients.
Early: pink puffer, ↑PCO₂
Late: Blue bloater, ↑PCO₂ & ↓PO₂
What famous textbook writer developed polio?
What did this prevent him from becoming?
Guyton developed Polio and was unable to become a cardiac surgeon.
How was polio contracted?
What charity group was originally created to combat polio?
- Swimming pools
- March for Dimes
What drug class, mentioned in class, when combined with alcohol will lead to severe consequences and possible death?
Barbiturates
Which two commonly used anesthetics won’t cause depression of the central nervous system?
Ketamine and Dexmedetomidine
What is the common pathophysiology of someone with an impact injury who had “the wind knocked out of them” ?
Phrenic nerve spasm
Is the respiratory system affected with a C6 injury?
Yes; diaphragm is innervated by C3-C5 but accessory muscles can still be affected.
Phrenic nerve injury, Eton-Lambert syndrome, sarcoidosis, extreme obesity, and pulmonary parenchymal disease are all examples of conditions that can cause _______ ________.
Respiratory acidosis
What effects will high altitude have on PO₂ and respiratory drive?
High altitude = ↓PO₂ and ↑Respiratory drive
What drug class can cause respiratory alkalosis?
Salicylates (ex. aspirin; stimulate the breathing centers of the CNS)
Progesterone, encephalitis/meningitis, anxiety, salicylates, and asthma are examples of conditions that can cause _______ ________.
Respiratory Alkalosis
