Final Exam - Acid/Base II Flashcards
(50 cards)
What is the role of a buffer?
How does it function?
- Buffers mitigate changes in H+ ion changes which helps prevent large chagnes in pH
- Buffers will either bind to a H+ if the body is more acidic, or release it’s proton if the body is too alkaline
Buffer + H+ ⇆ HBuffer
A buffer is best a managing pH at what value?
pH that matches it’s pK
What is the pK of HCO3- as a buffer?
pK = 6.1
Lower because works better at managing acidosis than alkalosis
What is the isohydric principle?
- All of the buffering systems work on the same pool of protons
- This means that the buffering systems work better together than they do individually
Why do we not include albumin in the protein portion of the buffering system?
- Because there are much more RBC in the plasma than albumin, and therefore lots and lots of Hb
- Albumin’s primary role is maintaing osmotic pressure of the vascular system
Explain what occurs when the steepness of the buffering line increases in the below diagram?
- As the buffer line becomes steeper from increased amounts of HCO3-, Hb, or phospate, there is an increased buffering capacity or resistance to changes in pH
- For instance, normally at a pCO2 of 60 mmHg the pH would be 7.25 with a [H+] of 55 nmol/L
- But when the steepness is increased, the isobars move closer to normal - and at the same pCO2 of 60 mmHg, the pH is close to 7.3 with a [H+] of 50 nmol/L
Explain what occurs when the steepness of the buffering line decreases in the below diagram?
- Decreased slope means there are less amounts of the buffering components working
- This pushes the isobars further from normal
- This means that compared to normal, for a pCO2 of 60 mmHg, the pH will be lower and the [H+] will be higher - the body is less capable to resist/manage a change in pH
What is the name of this diagram?
Nomogram
Describe changes in pH, pCO2, and [HCO3-] during acute respiratory acidosis?
pCO2: Increased (hypoventilation)
pH: Decreased ( ↑CO2 = ↑ H+)
[HCO3-] : Slightly increased due to increased formation of H2CO3 (not enough to buffer all of the excess H+ produced)
Describe changes in pH, pCO2, and [HCO3-] during acute respiratory alkalosis?
pCO2: Decreased (Hyperventilation)
pH: Increased (Less H+)
HCO3- : Slightly decreased due to less CO2
Describe changes in pH, pCO2, and [HCO3-] during chronic respiratory acidosis?
pCO2: Increased
pH: Slightly decreased or even normal (kidneys buffering now)
HCO3- : Large increase from kidneys
Describe changes in pH, pCO2, and [HCO3-] during chronic respiratory alkalosis?
pCO2: Decreased
pH: Slightly elevated or normal
HCO3-: Decreased (kidneys removing excess bicarb)
Describe changes in pH, pCO2, and [HCO3-] during metabolic acidosis?
pCO2: Decreased (d/t lung compensation for lack of bicarb)
pH: Decreased
HCO3-: Decreased (lack of production causing the acidosis)
Describe changes in pH, pCO2, and [HCO3-] during metabolic alkalosis?
pCO2: Increased (lungs compensating for increased bicarb)
pH: Increased
HCO3-: Increased (increased production causing the alkalosis)
Common causes of respiratory acidosis (give the broad categories)
- Depression of respiratory control centers
- NM disorders
- Chest wall restriction
- Lung restriction
- Pulm. parenchymal diseases
- Airway obstruction
What can cause depression of the respiratory control centers?
- Anesthesia
- Sedatives
- Opiates
- Brain injury
- Severe hypercapnia or hypoxia
Think hypoventilation
What are some NM disorders that would cause respiratory acidosis?
- SCI
- Phrenic nerve injury (or damage to accessory muscle nerves)
- Polio
- Guillain-Barre
- Botulism
- Tetanus
- Paralytics
What can cause respiratory acidosis from chest wall restriction?
- Kyphoscoliosis
- Extreme obesity
What can cause respiratory acidosis from lung restriction?
- Fibrosis
- Sarcoidosis
- Pnemothorax
- Pleural effusions
What can cause respiratory acidosis from pulmonary parenchymal disease?
- Pneumonia
- Pulmonary edema
What can cause respiratory acidosis from airway obstruction?
- COPD
- Asthma
- Upper airway obstruction (tumors, paralyzed cords)
Prevents CO2 removal
What are the common causes of respiratory alkalosis (broad categories)?
- CNS overactivity
- Drugs or hormones
- Bacteremia
- Pulm disease (asthma)
- Hypoxia; high altitude
What are the causes of CNS overactivity leading to respiratory alkalosis?
- Anxiety
- Hyperventilation syndrome
- Cerebral inflammation (encephalitis)
- Tumors
What are some drugs and hormones that could cause respiratroy alkalosis?
- Salicylate toxicity
- Progesterone (causes pregnant women to breathe more)
