Acid-Base: L40 - Acid Base Balance Flashcards
Define an acid.
Chemical that ‘releases’ H+ ions.
Define a base.
Chemical that ‘takes up’ H+ ions.
Define a buffer.
Substances or mechanisms that act to minimise changes in pH when H+ concentration is altered.
Define pH.
Concentration of H+ ions = -log [H+]
Define acidosis.
pH
Define alkalosis.
pH>7.45
Why is it important to regulate pH?
Influences enzyme activity.
Regulates ion transport mechanisms.
Cells - metabolism, DNA synthesis, growth
CNS.
What does alkalosis result in?
Headache, drowsy, tetany, convulsions.
What does acidosis result in?
Results in respiratory dysfunction, drowsiness, progressing to coma.
What are some gains of H+ ions?
–Generation of H+ from CO2
(CO2 made by cells, CO2+H2O->H2CO3->H+ + HCO3-)
–Production of non-volatile acids from the metabolism of proteins and other organic molecules i.e. Production of phosphoric and sulphuric acid, lactic acid, ketone bones.
–Gain of H+ due to a loss of HCO3- in urine.
–Gain of H+ due to loss of HCO3- in diarrhoea or other non-gastric GI fluids.
What are some losses of H+ ions?
- -Utilisation of H+ in metabolism of various organic ions.
- -Loss of H+ in vomitus.
- -Loss of H+ in urine.
- -Hyperventilation (breathing out too much CO2).
Explain how H+ is ‘breathed out’.
CO2 produced by cells dissolves to form H+ ions when it enters the blood. These can bind to Hb, which effectively removes the ions from the solution and has a buffering effect (stops pH fluctuation). Once blood has reached the lungs, H+ recombines with HCO3- to make CO2 which is then breathed out from the lungs and H+ is removed.
Explain what is respiratory acidosis.
Respiratory acidosis is when the blood is acidic due to hypoventilation, not enough CO2 being breathed out so H+ is not being ‘breathed out’ so blood is acidic.
Explain what is respiratory alkalosis.
Respiratory alkalosis is when the you hyperventilate and let out too much CO2, and so you breathe out too much H+, so blood becomes basic.
Explain buffering H+ from acids produced in metabolism.
Many acids are produced from metabolism including ketone bodies, lactic acid, sulphuric and phosphoric acid. These, like CO2 need to be buffered and excreted. The strong acids produced in metabolism can combine with substances in the blood to form weak acids. This reduces the effect of H+ ions on pH and buffers the solution. These buffers are bicarbonate, proteins and phosphate. H+ may then combine with bicarbonate to create CO2 which can then be excreted via lungs. H+ may also be secreted into renal tubules to be excreted by kidneys. Bicarbonate must now be replaced by kidneys to continually combine with H+ to make H+ no longer a threat. In this way, respiratory and renal systems work together to regulate pH of blood.
