Life at the Cellular Level 2 - pH Flashcards
What does water dissociate into?
hydrogen ions (h+) and hydroxide ions (OH-)
What does pH measure?
pH is the way of designating the concentration of H+ in any aqueous solution.
1 pH unit represents a ten fold increase or decrease in hydrogen ions.
Blood pH level meanings?
6-7: death
7-7.35: acidosis
7.35-7.45: normal
7.45-7.8: alkalosis
7.8-9: death
What is a buffer (basic)?
Buffers are solutions that resist changes in pH.
Why is optimal pH important in body?
Many biomolecules (proteins, DNA) are affected by pH as their shape is dictated by the pH of their environment, so for optimal activity they must be at an optimal pH.
How is optimal pH maintained in body?
Optimal pH is maintained by using weak acids and their bases as buffer systems within cells and organisms.
Which buffer is important in cytoplasm of cells?
The phosphate buffer system is important and can maintain changes of pH between 5.9 and 7.9.
H2PO4- –> H+ + HPO4 (2-)
Which buffer is important in plasma?
The bicarbonate buffer system is important
and concentration of H2CO3 depends on conc of CO2 .
What can happen if human blood plasma has drastic pH change?
irreparable cell damage, disastrous metabolic effects and death.
What affects bicarbonate buffer system?
Lung: increase or decrease in ventilation will change CO2 levels.
Kidney: changes in bicarbonate reabsorption or secretion change overall plasma bicarbonate.
What does the Henderson-Hasselbalch equation show?
can be used to calculate how the pH of a physiological solution will respond to changes in either the conjugate acid or base.
pH= pKa + log( A-)/(HA)
conjugate base/ weak acid
How does bicarbonate buffer system work?
Instead, as these acidic products are released into the blood, the bicarbonate ions act to buffer the H+ to prevent a rapid fall in blood pH. As free [H+] rises so does H2CO3 as the equation is pushed to the left. The bicarbonate “mops up” free H+ and limits (but does not completely prevent) the fall in pH.
By measuring blood pH, [HCO3-] and [CO2] the Henderson-Hasselbalch equation can be used to check how much buffering capacity a patient has.
What chemicals cause acid base disorders by their concentration changing?
HCO3- and CO2.
What causes acidosis?
Increase in CO2- respiratory acidosis
Decrease in HCO3- - metabolic acidosis
What causes alkalosis?
Decrease in CO2- respiratory alkalosis
increase in HCO3- - metabolic alkalosis
