life @ cellular level - water & pH Flashcards
why do lipid soluble/hydrophobic molecules do not dissolve readily in water?
they are non-polar and uncharged
what is the hydrophobic effect?
Hydrophobic molecules cluster and arrange themselves in water to minimise contact with it.
what’s the difference between miscelles and liposomes?
Miscelles have a sphere with a single phospholipid layer with no core.
Liposomes have a sphere with a lipid bilayer outer shell and a hollow core
they might have been the origin of the cell membrane.
what is the difference between acidic and basic (alkaline) solutions?
Acidic solutions have a greater [H+] and lower [OH-]
Basic (alkaline) solutions have a lower [H+] and higher [OH-]
what is a chlyomicron?
a liposome-like structure with a hydrophilic/polar outer shell made up of phospholipids and proteins that transports lipids in the blood
What’s the difference between strong acids/bases vs weak acids/bases?
Strong acids, like HCl, fully dissociate into H+ and Cl+.
Strong bases, like NaOH, fully dissociate into Na+ and OH-.
Weak acids and bases are only partially dissociate, this gives them the ability to act as buffers
what is the henderson-hasselbalch equation?
An equation used to calculate how the pH of a physiological solution will respond to changes in either the conjugate acid or base
The more [Buffer] you have, the more pH goes up
The more [H-buffer] you have, the more pH goes down
What are the clinical implications of the Henderson-Hasselbalch equation?
Respiratory acidosis and alkalosis (changes in ECF pH with respiratory origin)
Metabolic acidosis and alkalosis (changes in ECF pH with metabolic origin)
What happens to the pH levels if CO2 builds up because of a change in lung function e.g. pulmonary obstruction?
According to the bicarbonate buffer system,
an increase in CO2 will lead to an increase in H2CO3
breaks down to H+ and HCO3-
leads to a decrease in pH levels because of a rise in free hydrogen ion concentration or….
According to the Henderson-Hasselbalch equation, an increase in CO2 will lead to an increase in the denominator [H-buffer] which is H2CO3 but can be substituted with CO2, and since there is an inverse proportion between pH and [H-buffer], the pH level will fall.
RESPIRATORY ACIDOSIS
What happens to the pH levels if CO2 goes down because of a change in lung function? and what is the condition called?
According to the bicarbonate buffer system, a decrease in CO2 will lead to an decrease in H2CO3 which then breaks down to H+ and HCO3- leading to a increase in pH levels because of a decline in free hydrogen ion concentration.
OR
According to the Henderson-Hasselbalch equation, a decrease in CO2 will lead to a decrease in the denominator [H-buffer] which is H2CO3 but can be substituted with CO2, and since there is an inverse proportion between pH and [H-buffer], the pH level will rise.
RESPIRATORY ALKALOSIS
What happens to Aspirin (weak acid, dissociates to create pH of 3.5 in water) when placed in an environment where the pH is 1.5?
H-buffer increases and buffer decreases.
This is due to the extra H+ in the stomach (because of low pH) which forces more of the Aspirin into the protonated form [H-buffer].
Then the protonated, uncharged form of Aspirin can be easily absorbed across the stomach wall, into the blood.
How does the bicarbonate HCO3- buffer system work in the blood when [H+] increases?
If [H+] ↑ and starts decreasing the pH levels
- The bicarbonate ion acts as a buffer to prevent a rapid fall in pH levels.
as H+ increases it bonds with HCO3- making more H2CO3 and returns pH to optimal level.
How does the bicarbonate HCO3- buffer system work in the blood when [H+] decreases?
If [H+] ↓ and starts increasing the pH levels
The carbonic acid acts as a buffer to prevent a rapid rise in pH levels.
as H2CO3 dissociates making more H+ and HCO3- and returns pH to optimal level.
what is the optimal blood pH level for a average, healthy person is approximately?
7.4
what does ΔG = 0 mean?
the reaction is at an equilibrium which is incompatible with life.
Reactions usually do not reach equilibrium in our bodies as they are open systems i.e. energy passes from the environment to the organism and back to the environment.
