CGIER 40 - Buffer systems of the body Flashcards
buffer system
CHEMICAL EQUILIBRIA systems that typically consist of a weak acid and weak base of equal quantities and resist serious changes in pH upon addition of acids or bases.
what do metabolic reaction produce
continuously produce acids
how much carbonic acid do cells produce each day
produce an average of ~ 10-20 moles of carbonic acid each day (equivalent to 1-2 litres of concentrated HCl).
how is carbonic acid removed from body produced by cells
removed from the cells and carried to the organs of excretion without disrupting the pH of the blood.
what buffer system controls ph of blood
the pH of the blood is controlled by the bicarbonate buffer system
name the pH buffer that works in cells
phosphate buffer
phosphate buffer system
H2PO4- <===> H3O+ + HPO4^2-
bicarbonate buffer system
CO2 + H2O <===> H2CO3 <===> H3O+ + HCO3-
what feature can describe proteins
amphoteric.
NH2CCOOH products of amino acid
NH3+
COO-
Le Chatelier’s Principle
If the conditions of a system, initially at equilibrium, are changed, the equilibrium will shift in such a direction as to tend to restore the original conditions.
where will the bicarbonate buffer system shift if a strong acid is added
- driving the reaction to the left and forming more carbonic acid
- carbonic acid is unstable and will decompose rapidly to form carbon dioxide and water
where will the bicarbonate buffer system shift if a strong base is added
- base will react with the H3O+ ions present to produce water
- thus decreasing the [H3O+] in the system.
- this will drive the above reaction to the right.
an abnormal increase in acid levels in blood can lead to …
respiratory acidosis
metabolic acidosis
how does body try to compensate for respiratory acidosis and metabolic acidosis
expelling the excess carbon dioxide formed from the carbonic acid, through an increase in the rate of breathing.
increasing the excretion of H+ and the retention of HCO3- by the kidneys.
what does respiratory acidosis result from
CO2 retention
pH blood decreases
causes of respiratory acidosis
hypoventilation emphysema or asthma congestive heart failure Bronchopneumonia drugs that depress the brain respiratory centre
what does metabolic acidosis result from
increase in H+
pH decrease in blood
causes of metabolic acidosis
diabetes mellitus - acidic compounds formed from metabolism of fats
kidney failure
severe diarrhoea causing loss of HCO3-
excessive exercise
compensatory of metabolic and respiratory acidosis
increase rate of breathing
kidneys excrete acid urine
AN ABNORMAL DECREASE IN ACID LEVELS IN BLOOD.
The pH of the blood increases.
‘Respiratory Alkalosis’
Metabolic Alkalosis’
how does body try to restore normal pH when the blood is in alkalosis
expelling less carbon dioxide by decreasing the rate of breathing.
increase the excretion of HCO3- by the kidneys, resulting inalkaline urine (pH>7).
what results in respiratory alkalosis
rapid expulsion of CO2 (elevated breathing rate)
blood pH increases
causes of respiratory alkalosis
hyperventilation
high fevers
trauma
hysteria
compensatory for respiratory and metabolic alkalosis
slower rate of breathing
kidneys excrete less acid
what does metabolic alkalosis result from
increase in alkaline components such as HCO3- in blood
blood pH increases
causes of metabolic alkalosis
severe vomiting - loss of acid stomach
excess ingestion of alkaline substances
kidney disease
acidosis equation
CO2 /\ + H2O H2CO <=>HCO3- + H3O+(excreted in urine)
alkalosis equation
CO2 V + H2O H2CO3 <==> HCO3-(excreted in urine) + H3O+
where will the phosphate buffer system shift to if a strong acid is added
will drive the reaction to the left,
• thus increasing the [H2PO4-] in the system (which is only weakly acidic).
Large amounts of H2PO4- will result in acidosis, but the body will eliminate the excess in urine.
where will the phosphate buffer system shift to if a strong base is added
• will drive the reaction to the right as the H+ ion reacts with the base to form water
Large amounts of HPO42- would be found in alkalosis, but under normal kidney function, the HPO42- is also excreted in the urine.
