Week 3 - H - Physiology 8 - Arterial blood gases (acidosis&alkalosis) Flashcards
What is a person’s normal plasma pH? When is it acidic and when is it alkali?
pH - 7.35 to 7.45 Acidic - below 7.35 and lkali is above 7.45
What is the normal bicarbonate and CO2 range for a patient?
Bicarbonate (HCO3-) - 23 to 27 mmol/l CO2 - 35-45 mmol/l
If normal acid-base balance is disrupted, the first priority is to restore pH to 7.4 as soon as possible What is this known as?
This is known as compensation
What is the correction of the acid base disturbance then?
This is the stage of returning the HCO3-, CO2 and pH levels to normal Compensation is the restoration of pH irrespective of what happens to [HCO3-]p and PCO2
When an acidosis occurs, what happens to the CO2 levels and pH levles?
CO2 levels increase causing a fall in pH in acidotic conditions (CO2 becomes an acid in solution)
What is the main buffer system in the human body?
The bicarbonate buffer system
If there is a riise in H+ ion concentration therefore causing a decrease in pH, what in the blood quickly binds to the increase [H+] to buffer the blood? What regenerates this ion?
HCO3- binds to the increased hydrogen ions The kidney then works to regenerate the bicarbonate used
How is the bicarbonate used to monitor the H+ levels reasborbed?
Once it binds to H+ it becomes H2CO3 (carbonic acid) filtered into the tubular lumen, this then dissociates to become CO2 and HCO3- and reenters the tubualr cells/interstitial fluid
What is the Henderson Hasselbach equation?
pH = pK + log [A-/HA]
In the henderson hasselbach equation, if regarding the bicarbonate and CO2 levels, what is the pH proportional to?
pH is proportional to the HCO3- levels and inversely proportional to the levels of CO2 in the blood
A blood-gas analyser can measure pH and PCO2 [HCO3-] can be calculated What type of diagram can these variables be plotted on?
Can be plotted on a Davenport diagram
What type of arterial blood gas does the green circle represent?
Represents the normal value
What are some cause of CO2 retention in the body?
Type II repsiratory failure - chronic bronhcitis, emphsyema Respiratory depression
What is the sydnrome characterised by obesity and hypoventialtion which drives a person into hypercapnia?
This is Pickwickian Syndrome
An increase in carbon dioxide levels drives the equilibirum in which direction?
Drives the equilibrium to the right therefore accounting for the increased hydrogen ions