L29 and L30 Acid-Base Balance Flashcards
What are the normal pH ranges in the body?
7.35-7.45
What pH range is compatible with life?
6.8-8.0
Which of the following is significantly affected by changes in pH?
A) Nerve excitability
B) Enzyme activity
C) Potassium homeostasis
D) All of the above
D) All of the above
Disorientation, coma and death are results of decreased CNS activity.
Is this suggestive of acidosis or alkalosis?
Acidosis
Acidosis causes decreased CNS activity
Pins and needles and muscle twitching are potential consequences of:
A) Acidosis
B) Alkalosis
C) Both A and B
D) Neither A nor B
B) Alkalosis
These are signs of increased CNS activity, which is caused by alkalosis
How can changes in pH affect enzyme activity?
Changing the R-group charge of an AA can cause a change in shape.An enzyme’s shape is vital to functioning
Acidosis causes:
A) ↑ secretion of H+ B) ↑ secretion of K+ C) ↓ secretion of H+ D) ↓ secretion of K+ E) Both A and B F) Both A and D G) Both B and C
F) Both A and D
Acidosis: ↑ secretion of H+ results in ↓ secretion of K+, leading to HYPERkalaemia
Alkalosis causes:
A) ↑ secretion of H+ B) ↑ secretion of K+ C) ↓ secretion of H+ D) ↓ secretion of K+ E) Both A and B F) Both A and D G) Both B and C
G) Both B and C
Alkalosis: ↓ secretion of H+ results in ↑ secretion of K+, leading to HYPOkalaemia
Acidosis results in:
A) Increased CNS activity
B) Hypokalaemia
C) Reduced enzyme activity
D) All of the above
C) Reduced enzyme activity
How can intake of protein affect pH?
↓ pH
Phosphorus and sulphur in proteins are converted into strong acids: phosphoric and sulphuric.
Does fruit digestion yield release of acids or bases?
Bases
Anaerobic glycolysis results in what change to pH?
↓ pH
Anaerobic glycolysis produces lactic acid (weak acid)
What is the quickest mechanism that reverses pH changes?
Blood buffers (takes seconds)
Which acid-base mechanism takes minutes to reverse a change in pH?
Respiratory compensation
Which acid-base mechanism takes hours to days for it to reverse a change in pH?
Renal compensation (takes hours to days)
True or false: A buffer is a weak acid or base
True
Buffers absorb protons or conjugate bases. Blood buffering is highly effective
What is the major blood buffer?
Bicarbonate
In addition to bicarbonate, what are the other blood buffering systems?
Haemoglobin
Plasma proteins
Phosphate
True or false: Phosphate is a good urinary buffer
True, because there is little reabsorption
When can respiratory compensation NOT contribute to restoration of pH balance?
When the pH change is due to respiratory disease
Buffers and renal compensation become very important
What can the kidneys regulate to compensate for changes in pH?
Bicarbonate reabsorption
Proton secretion
In respiratory compensation, regulation of which substance reverses the pH change?
Carbon dioxide
In acidosis:
A) Plasma H+ is ↑
B) Less HCO3 is filtered by the kidneys
C) Renal H+ secretion increases
D) All of the above
D) All of the above
Why do the kidneys filter less bicarbonate in acidosis?
Bicarbonate buffers the excess acid, therefore you want more of it in the blood
What substances buffer acid in urine?
Phosphate and ammonia
Why is acid buffered in urine?
Buffers mop up protons in urine, helping maintain the H+ gradient. This allows more H+ to be pulled into the urine and raise the pH of the blood in acidotic conditions
True or false: Phosphate is produced from glutamine metabolism
False
Ammonia is produced from glutamine metabolism
True or false: Production of ammonia is up-regulated during acidosis
True
What is the difference between compensation and correction (referring to pH balance)?
Compensation:
- Starts immediately
- Corrects pH change only
- PCO2 and HCO3 sacrificed to restore pH
Correction:
- Complete restoration of pH, PCO2 and HCO3
True or false: Respiratory causes of pH change are normally associated with CO2, while metabolic causes are normally associated with HCO3
True
What is the uncompensated result of respiratory acidosis?
↑ CO2
↓ pH
↑ HCO3 (but within normal limits)
What is the result of respiratory acidosis with metabolic compensation?
↑ CO2
↑ HCO3 (outside normal limits)
What are the clinical causes of respiratory acidosis?
Obstructive respiratory disease (emphysema)
Pulmonary oedema
Drug-induced respiratory depression (opiates)
Neuromuscular conditions
What are the clinical causes of respiratory alkalosis?
Anxiety, fear
Pain
Aspirin poisoning
High altitude
What are the clinical causes of metabolic acidosis?
Diabetic ketoacidosis
Diarrhoea (high excretion of HCO3)
Heavy exercise (↑ lactic acid)
Renal failure (↓ secretion of protons)
What are the clinical causes of metabolic alkalosis?
Overdose of antacids
Vomiting (loss of HCl)
