Acid base imbalances Flashcards
If the ph of arterial blood rises above 7.45, this would be called
alkalosis
if the ph of arterial blood falls below 7.35, this would be called…
acidosis
cell death will occur if the ph is higher than… or lower than ….
7.7 and 6.8
normal body metabolism produces an excess of acids that need to be removed to retain homeostasis, name 3 acids produced by metabolism
- carbonic acid from CO2 - aerobic respiration
- Lactic acid from anaerobic respiration
- ketones from the use of lipids as an energy source
what are the two types of buffer systems that regulate ph homeostasis
- chemical and physiological
what is the response time for the chemical buffer systems and name 3 types
- immediate
- bicarbonate
- phosphate
- protein
what are the two types of physiological buffer systems and their according response time?
- Respiratory (minutes)
- renal (hours)
How do chemical buffers work?
buffers react with a relatively strong acid or base to replace it with a relatively weak one, they do this by either absorbing of releasing hydrogen ions to reduce the change in ph
how does the bicarbonate-carbonic acid buffer system work
to maintain normal blood ph, a proportion of 20 bicarbonate ions (HCO3) to 1 carbonic acid (H2CO3) or carbon dioxide is required this reaction is catalysed by carbonic anhydrase in rbc’s
how is ph regulated by the respiratory system
if PCO2 in the blood rises it activates the medullary chemoreceptors which cause an increase in respiratory rate and depth, this also happens if there is a rise in plasma H+ which activates the peripheral chemoreceptors having the same effect. both cause more CO2 to be removed from the blood driving bicarbonate-carbonic acid buffer system to the left which reduces hydrogen concentration
how does hypoventilation impact ph homeostasis
respiratory acidosis will occur if ph is less than 7.35 due to the retention of CO2 driving the buffer system to the right and therefore raising hydrogen ion concentration
how does hyperventilation impact ph homeostasis
respiratory alkalosis will occur if ph is above 7.45 for to much loss of CO2 driving buffer system to the left thereby lowering hydrogen ion oncentration
how do the kidney’s regulate homeostasis and what does this buffer system rely on
kidneys can excrete or retain both hydrogen and bicarbonate ions during the filtration process
- this buffer system relies on norml kidney function
if either the repiratory or renal system are impaired causing a change in ph, what can happen to help solve this issue
the system not impaired may compensate in an attempt to move ph closures to normal range
what are the 3 aspects of naming an acid base disorder
- either be acidosis or alkalosis
- either caused by respiratory or non-respiratory (metabolic)
- can be partly or fully compensated or uncompensated
eg. compensated respiratory alkalosis
what would the ph, CO2 and bicarbonate levels be of a person who has uncompensated respiratory acidosis
ph = less than 7.35 CO2 = increased (greater than 45mmHg) bicarbonate = normal
what would the ph, CO2 and bicarbonate levels be of a person who has uncompensated metabolic acidosis
ph = less than 7.35 CO2 = normal Bicarbonate = decreased (less than 22mEq/L)
what is a cause of respiratory acidosis
hypopventilation
what is 3 causes of metabolic acidosis
- severe diarrhea (loss of bicarbonate ion from gut)
- renal disease ( can remove hydrogen ions properly)
= diabetic ketoacidosis
how can acidosis cause hyperkalaemia? and what is consequence of this ?
- due to hydroge entering cells to exchange for k+ cells leaving into ECF
- acidosis causes and decrease in secretion of k+ from kidney
- hyperkalaemia can cause cardiac arrythimias
what will the ph, CO2 and bicarbonate levels be for a person with uncompensated respiratory alkalosis?
- ph = greater than 7.45
- CO2 = decreased (less than 35mmHg)
- bicarbonate = normal
what can cause respiratiory alkalosis?
hyperventialtion
what would the ph, CO2 and bicarbonate levels show on a blood gas test for somenone who has uncompensated metabolic alkalosis
- ph= greater than 7.45
- CO2 = normal
- Bicarbonate = increased ( greater than 26mEq/L)
what are 3 potential causes of metabolic alkalosis?
- vomiting (loss of acid)
- some diuretics cause loss of K+ and H+ at kidney
- overdose of antacids
the body will try to compensate if the is an issue with one buffer system to attepmt to maintain homeostasis, how can we tell if this is happening?
- on the blood gases results the amount of HCO3 or H+ will oppose the observed deviation in blood ph
what would the ph, CO2 and bicarbonate levels show on the blood gases results of someone who has compensated respiratory acidosis and how is this acheived?
- ph = either normal (if fully compensated) or below 7.35 (if only partly compensated)
- CO2 = increased ( greater than 45mmHg)
- Bicarbonate = elevated
- kidneys retain HCO3 ions and secrete H+ ions
what would the ph, CO2 and bicarbonate levels show on the blood gases result of someone who has compensated metabolic alkalosis and how is this achieved?
- ph = either normal (if fully compensated) or above 7.45 (if partly compensated)
- CO2 = elevated
- Bicarbonate = increased (above 26mEq/L)
- the lungs will retain CO2 and therefor increase hydrogen concentration
Blood gases are tests used to detect disorders what things are measured in the arterial blood and what would be the normal range for each measurement?
- ph = 7.35 - 7.45
- CO2 (pCO2) = 35 - 45 mmHg
- PO2 = 80-100mmHg
- HCO3 = 22-32mmol/L
- %saturation = 95 100%
