Lecture 5: Control of Respiration Flashcards
why would you take arterial blood gas rather than vein
to assess:
- acid base balance
- ventilatory status
what are the important buffers in the blood
- bicarbonate
- circulatory proteins with histodine residues, eg albumim
- phosphates
how can we measure the levels of fixed acids
the anion gap:
difference between uncounted anions and uncounted cations
what are the main causes of non-anion gap metabolic acidosis
loss of bicarbonate through:
- renal tubular acidosis
- gastrointestinal losses
- acetozolamide
- excess chloride administration
what is the range of acidaemia
<7.38
what is the range of alkalaemia
> 7.44
what are causes of metabolic alkalosis
- vomiting as it removes H+
- increased aldosterone
what are causes of respiratory acidosis
- increased dead space eg emphysema
- muscle weakness
- depression of respiratory centre
what are causes of respiratory alkalosis
hyperventilation due to pain or anxiety or pregnancy
where’s the respiratory centre in the brain
pons and medulla in the hindbrain
what are the groups of the medulla and what do they do
- dorsal respiratory: trigger inspiratory impulses
- ventral respiratory: triggers inspiratory and expiratory impulses during exercise
what are the inspiratory muscles
- diaphragms
- external intercostal muscles
- sternocleidomastoid
- scalene muscles
what are the muscles of exhalation
- abdominal wall
- internal intercostal muscles
what are the mechano and irritant receptors in the lung
- C-fibre nociceptors
- mechanically sensitive receptors
- lung stretch receptors
where are central chemosensors and what do they detect
- hindbrain
- detect H+ conc. in CSF
- very sensitive
