The role of ventilation in acid/base balance Flashcards
What does the function of proteins depend on and how is this achieved?
→ Depends on a specific secondary, tertiary and quaternary structure
→ Achieved by intra and inter chain bonding
What can denature proteins?
→ Temperature, pH, pressure can denature proteins
How is arterial pH tightly regulated?
→ Presence of buffering systems and regulating the level of molecules associated with acid/base production
What is a buffer?
→ Weak acid + conjugate base
How do buffers work when H+ is added?
→ When there are excess H+ ions present they are mopped up by reacting with the conjugate base to form the weak acid
→ H+ + HCO3- ⇌ H2CO3
→ The end product is much less acidic
How do buffers work when H+ is removed?
→ If H+ ions are removed the weak acid will dissociate to increase the H+ ion concentration
Why does the pH remain relatively stable with a buffer?
→ Any H+ formed by the addition of strong acid will react with the conjugate base to form a weaker acid
What are buffers used for?
→ Resisting sharp changes in pH
What are 3 examples of intracellular buffers?
→ Phosphate buffer system
→ Amino acids/ proteins
→ Haemoglobin (RBC)
What are 2 examples of extracellular buffers?
→Bicarbonate buffer system
→ Plasma proteins
What maintains blood homeostasis?
→ CO2 bicarbonate buffering system
How does the level of CO2 in the body determine acidity?
→ CO2 + H20 ⇌ H+ + HCO3-
→ CO2 reacts with water to form bicarbonate
→ Bicarbonate dissociates to form H+ and HCO3-
What happens during acidosis?
→ CO2 builds up in the blood
→ More carbonic acid is produced
→ H+ increases
What happens during alkalosis?
→ CO2 is removed from the blood
→ Less carbonic acid
→ H+ decreases
How do the lungs contribute to acid/base balance?
→ Regulate CO2 levels
How can you diagnose respiratory distress?
→ ABG and pH
What is blood pH proportional to?
→ pH ∝ log (HCO3-)/PaCO2
What does the renal system control and what is the timeframe for this?
→ The concentration of bicarbonate ions
→ time frame (hours to days)
What does the respiratory system control and what is the time frame for this?
→ The partial pressure of CO2
→ time frame ( minutes)
What happens if PaCO2 increases?
→ pH decreases
What happens if PaCO2 decreases?
→ pH increases
What happens if HCO3- increases?
→ pH increases
What happens if HCO3- decreases?
→ pH decreases
What is the balance of CO2 and HCO3- like in acidosis?
→ CO2 is too high
→ HCO3- is too low
What is respiratory acidosis?
→ CO2 is too high
What is metabolic acidosis?
→ HCO3- is too low
What is the balance of CO2 and HCO3- like in alkalosis?
→ CO2 is too low
→ HCO3- is too high
What is respiratory alkalosis?
→ CO2 is low
What is metabolic alkalosis?
→ HCO3- is too high
What are the causes of acidosis?
→ Hypercapnia → Increased lactic acid → Increased ketone bodies → Decreased kidney acid excretion → Decreased HCO3- reabsorption → Diarrhoea
What are the effects of acidosis?
→ Tachypnoea → Muscular weakness → Headache → Confusion + coma → Cardiac arrhythmia → Hyperkalaemia
What are the compensatory mechanisms for acidosis?
→ Hyperventilation
→ Decrease in HCO3- excretion
What are the causes of alkalosis?
→ Hypocapnia
→ Vomiting
→ Increased kidney acid excretion
→ Increased alkalotic agent consumption
What are the effects of alkalosis?
→ Bradypnoea → Muscular weakness, cramps, tetany → Headache, nausea → Lightheadedness, confusion + coma → Cardiac arrhythmia → Hypokalaemia
What are compensatory mechanisms for alkalosis?
→ Hypoventilation
→ Increased HCO3- excretion
How can acidosis induce hyperkalaemia?
Acidosis increases the concentration of extracellular H+
⇓
Decreases the concentration gradient
⇓
Less H+ excretion via the H+/ Na+ exchange
⇓
Decreased levels of Na+ affect the Na+/K+ exchange
⇓
Decreasing the K+ absorption into the cell
⇓
K+ accumulation in the serum is hyperkalaemia
⇓
Leads to cardiac arrhythmias and muscle weakness
How can alkalosis induce cerebral vasoconstriction?
CO2 acts as a vasodilator in blood vessels
⇓
In alkalosis with decreased CO2 and H+ there is vasoconstriction in cerebral arteries
⇓
Decrease leads to headaches, lightheadedness, confusion + seizures
