Acid Base Balance (struc) Flashcards
ACID-BASE BALANCE
Metabolic processes in the body can produce large amounts of ?:
* Carbonic (H2CO3)
* ? (metabolism of cysteine and methionine)
* ? (metabolism of phosphates and proteins)
* ? acid (incomplete oxidation of glucose)
These products are transported to the lungs and kidneys via (ECF → blood) without producing any major change in plasma ?
This is accomplished by:
* The ? capacity of blood
* ? mechanisms
* ? regulatory mechanisms
ACID-BASE BALANCE
Metabolic processes in the body can produce large amounts of acid:
* Carbonic (H2CO3)
* sulfuric (metabolism of cysteine and methionine)
* phosphoric (metabolism of phosphates and proteins)
* lactic acid (incomplete oxidation of glucose)
These products are transported to the lungs and kidneys via (ECF → blood) without producing any major change in plasma pH
This is accomplished by:
* The buffering capacity of blood
* respiratory mechanisms
* renal regulatory mechanisms
the capillary wall separates plasma and interstitial fluid
ECF = plasma + interstitial fluid
cell membrane separates interstitial fluid and intracellular fluid
ACID and BASE
An ACID is a proton ?
* Can ? a hydrogen ion (H+) to a solution
A BASE is a proton ?
* Can ? a hydrogen ion from a solution
HA -> (reversible arrow) H+ + A-
Ex: HCL -> H+ + Cl-
HCO3- + H+ -> H2CO3
ACID and BASE
An ACID is a proton donor
* Can donate a ? ion (H+) to a solution
A BASE is a proton acceptor
* Can accept a hydrogen ion from a solution
HA -> (reversible arrow) H+ + A-
Ex: HCL -> H+ + Cl-
HCO3- + H+ -> H2CO3
ACID and BASE
STRONG ACID
Dissociates very slowly or quickly? in a solution
releasing small or large? amounts of H+
E.g.: * ?, ? (Nitric acid), ? (sulfuric acid) *
A weak acid only ? dissociates in an aqueous solution (Ex: H2CO3 - carbonic acid)
STRONG BASE (Acceptor)
Reacts very quickly with ? removing it from a solution
E.g.: OH- (hydroxyl group) reacts with ? to form H2O
A weak base does not ? ionize in an aqueous solution (Ex: HCO3 -bicarbonate)
Most of the ? and ? involved in acid-base balance homeostasis in the body are strong or weak?
ACID and BASE
STRONG ACID
Dissociates very quickly in a solution
releasing large amounts of H+
E.g.: * HCL, HNO3 (Nitric acid), H2SO4 (sulfuric acid) *
A weak acid only partially dissociates in an aqueous solution (Ex: H2CO3 - carbonic acid)
STRONG BASE (Acceptor)
Reacts very quickly with H+ removing it from a solution
E.g.: OH- (hydroxyl group) reacts with H+ to form H2O
A weak base does not fully ionize in an aqueous solution (Ex: HCO3 -bicarbonate)
Most of the ACIDS and bases involved in acid-base balance homeostasis in the body are weak
CONCEPT OF ACIDITY
The ? of a solution refers to the chemical activity of ? ions (power of hydrogen)
* The difference between activity and concentration of H+ is not significant in body fluids
ACIDITY IS RELATED TO ? CONCENTRATION
The concentration of H+ ions is a ? times less than the most important ? in body fluids
* Nanoequivalents per liter (nEq/L) vs Milliequivalents per liter (mEq/L)
* Why is this so important??
CONCEPT OF ACIDITY
The acidity of a solution refers to the chemical activity of H+ ions (power of hydrogen)
* The difference between activity and concentration of H+ is not significant in body fluids
ACIDITY IS RELATED TO H+ CONCENTRATION
The concentration of H+ ions is a millions times less than the most important electrolytes in body fluids
* Nanoequivalents per liter (nEq/L) vs Milliequivalents per liter (mEq/L)
* Why is this so important??
CONCEPT OF ACIDITY
H+ ions are ? reactive!!!
* The proteins of the body have many ? ions
(i.e. charged amino acids with acidic and basic side chains (R- groups)
- These may gain or lose ? as [H+] changes, resulting in alterations
- Changes in * ? or ? configuration can affect ? structure and function *
[H+] of body fluids must be kept ?
- Important for enzyme function and cellular structure as:
activity of the ? pump decreases by half
when pH falls by #? unit
activity of ? (a key regulatory enzyme in the glycolytic pathway) decreases by ?% when pH decreases by only 0.1 unit
CONCEPT OF ACIDITY
H+ ions are highly reactive!!!
* The proteins of the body have many dissociable ions
(i.e. charged amino acids with acidic and basic side chains (R- groups)
- These may gain or lose protons as [H+] changes, resulting in alterations
- Changes in * charge or molecular configuration can affect protein structure and function *
[H+] of body fluids must be kept CONSTANT!
- Important for enzyme function and cellular structure as:
activity of the sodium-potassium-ATPase (Na+, K+-ATPase) pump decreases by half
when pH falls by 1 unit
activity of phosphofructokinase (a key regulatory enzyme in the glycolytic pathway) decreases by 90% when pH decreases by only 0.1 unit
CONCEPT of pH
pH is defined as the positive or negative? logarithm to the base of #? of the hydrogen ion concentration [H+]
The concept was introduced as an easier notation of the wide range of [H+] found in chemical systems
pH = -log10[H+] = log10 (1/[H+])
Hydrogen ion concentration [H+] determines the ? of the body ?
[H+] is precisely regulated in the body Measured as ? (power of ?)
CONCEPT of pH
pH is defined as the negative logarithm to the base of 10 of the hydrogen ion concentration [H+]
The concept was introduced as an easier notation of the wide range of [H+] found in chemical systems
pH = -log10[H+] = log10 (1/[H+])
Hydrogen ion concentration [H+] determines the pH of the body fluids
[H+] is precisely regulated in the body Measured as pH (power of hydrogen)
CONCEPT OF pH
Considering that the normal extracellular fluid [H+] is ? nEq/L or (0.00000004 N) :
[H+] = 40 nEq/L = 4x10-8 Eq/L
pH = -log10[4 x 10-8]
= -log(base10) to the power 4 - log(base10)10 to the power -8
= -(0.602) – (-8) = 8 - 0.602
= 7.398 (pH of blood)
[H+] is very low yet “powerful”
this is why H+ concentration is expressed as a ? function called ?
? pH: slightly lower than blood ~(7.2)
CONCEPT OF pH
Considering that the normal extracellular fluid [H+] is forty nEq/L or (0.00000004 N) :
[H+] = 40 nEq/L = 4x10-8 Eq/L
pH = -log10[4 x 10-8]
= -log(base10) to the power 4 - log(base10)10 to the power -8
= -(0.602) – (-8) = 8 - 0.602
= 7.398 (pH of blood)
[H+] is very low yet “powerful”
this is why H+ concentration is expressed as a logarithmic function called pH
intracellular pH: slightly lower than blood ~(7.2)
CONCEPT OF pH
- ? is a numeric scale used to specify the acidity or basicity/alkalinity of an aqueous solution
- In neutral pure water (pH ?) we find the ? amounts of H+ (acid) and OH- (base)
- There is an inverse relationship between pH and [H+]
The greater the [H+], the lower the pH:
-> Increase in [H+] = decrease pH in the blood = ?
-> Decrease in [H+] = increase pH in the blood = ?
CONCEPT OF pH
- pH is a numeric scale used to specify the acidity or basicity/alkalinity of an aqueous solution
- In neutral pure water (pH 7) we find the same amounts of H+ (acid) and OH- (base)
- There is an inverse relationship between pH and [H+]
The greater the [H+], the lower the pH:
-> Increase in [H+] = decrease pH in the blood = ACIDEMIA
-> Decrease in [H+] = increase pH in the blood = ALKALEMIA
- ACIDEMIA is the decrease in blood’s pH below ? limits
o The hydrogen ion concentration is ? normal limits - ? refers to the pathophysiological processes that cause net accumulation of acid in the body
- ALKALEMIA is the increase in blood’s pH above normal limits o The hydrogen ion concentration is __________ normal limits
- ? refers to the pathophysiological processes that cause net accumulation of alkali in the body
- ACIDEMIA is the decrease in blood’s pH below normal limits
o The hydrogen ion concentration is above normal limits - ACIDOSIS refers to the pathophysiological processes that cause net accumulation of acid in the body
- ALKALEMIA is the increase in blood’s pH ABOVE normal limits
o The hydrogen ion concentration is BELOW normal limits - ALKALOSIS refers to the pathophysiological processes that cause net accumulation of alkali in the body
Concept of pH
pH and [H+] do not vary ? with one another
They vary ?
A CHANGE OF 1 pH UNIT CHANGES THE HYDROGEN ION CONCENTRATION BY A FACTOR OF ?
Not Shown on Scale, but a pH 1; [H+]=0.1 pH = -log 10[H+]
Concept of pH
pH and [H+] do not vary linearly with one another
They vary exponentially
A CHANGE OF 1 pH UNIT CHANGES THE HYDROGEN ION CONCENTRATION BY A FACTOR OF 10
Not Shown on Scale, but a pH 1; [H+]=0.1 pH = -log 10[H+]
LAW OF MASS ACTION
“The velocity of a chemical reaction is proportional to the product of the ? of reactants”
o It explains and predicts the behavior of solutions in a ? equilibrium
o For the acid, there are two opposing reactions:
HA H+ + A-
o The velocity of the first and second reactions can be written:
v1=K1[HA]
v2 = K2 [H+][A-]
HA -> (k1) <- (k2) H+ + A- (see pic)
If V1 = V2 → chemical ?
Keq or simply K = equilibrium ?
(WHEN WE HAVE BUFFERING SYSTEM WORKING WELL then equilibrium constant occurs or EQUILIBRIUM done by the law of mass action
velocity of dissociation is the same as velocity of association)
LAW OF MASS ACTION
“The velocity of a chemical reaction is proportional to the product of the concentrations of reactants”
o It explains and predicts the behavior of solutions in a dynamic equilibrium
o For the acid, there are two opposing reactions:
HA H+ + A-
o The velocity of the first and second reactions can be written:
v1=K1[HA]
v2 = K2 [H+][A-]
HA -> (k1) <- (k2) H+ + A- (see pic)
If V1 = V2 → chemical equilibrium
Keq or simply K = equilibrium constant
(WHEN WE HAVE BUFFERING SYSTEM WORKING WELL then equilibrium constant occurs or EQUILIBRIUM done by the law of mass action
the velocity of dissociation is the same as the velocity of association)
CONCEPT OF BUFFERING
A Buffer is a compound that can ? or ? protons (hydrogen ions H+) and ? a change in pH
A Buffer solution consists of a ? acid and its ? base
Buffers reversibly bind ? and prevent major changes in ?
Blood buffers: first or second? line of defense to prevent major changes in blood ?
When a strong ? is added to a buffer solution containing a ? acid and its conjugated base, the dissociated H+ from the strong acid are donated to the ? and the change in pH is ?.
A buffered solution resists changes in pH
CONCEPT OF BUFFERING
A Buffer is a compound that can accept or donate protons (hydrogen ions H+) and minimize a change in pH
A Buffer solution consists of a weak acid and its conjugate base
Buffers reversibly bind H+ and prevent major changes in pH
Blood buffers: first line of defense to prevent major changes in blood pH
When a strong acid is added to a buffer solution containing a weak acid and its conjugated base, the dissociated H+ from the strong acid are donated to the base and the change in pH is minimized.
A buffered solution resists changes in pH
CONCEPT OF BUFFERING
There are many buffering systems in the body fluids
However, it is not necessary to measure all components of every buffering system
If one system is known, changes in another system can be predicted
? PRINCIPLE – multiple buffers in the same
solution are always in equilibrium
In clinical practice, the ? buffer system
is the one used to monitor acid-base balance.
Blood gas ? (partial pressure of CO2 and O2), pH, calculated ?
CONCEPT OF BUFFERING
There are many buffering systems in the body fluids
However, it is not necessary to measure all components of every buffering system
If one system is known, changes in another system can be predicted
ISOHYDRIC PRINCIPLE – multiple buffers in the same
solution are always in equilibrium
In clinical practice, the bicarbonate-carbonic acid buffer system is the one used to monitor acid-base balance.
Blood gas analysis (partial pressure of CO2 and O2), pH, calculated bicarbonates
ACID-BASE BALANCE
The ionic composition of body fluids is maintained within ? limits
Important for ? functioning of the cells
Over time, net production of ? by the organism must be matched by the excretion
Serious deviations of pH disrupt cell ?
-> Some enzymes could be reduced in activity by ?% with a change in pH by only 0.1 units
ACID-BASE BALANCE
The ionic composition of body fluids is maintained within narrow limits
Important for optimal functioning of the cells
Over time, net production of H+ by the organism must be matched by the excretion
Serious deviations of pH disrupt cell metabolism
-> Some enzymes could be reduced in activity by 90% with a change in pH by only 0.1 units
ACID-BASE BALANCE
There are three systems that can help regulate hydrogen ion concentration and pH in body fluids
1. ? buffer systems
* Manage the imbalance, act within seconds
2. ?
* Respiration, excretes CO2, act within seconds
3. ?
* Excrete/Reabsorb H+ and HCO3-, act within hours or days
physiological buffers include # and # from above.
The blood chemical buffers provide the first or second? defense against a change in blood ?, but the lungs and kidneys must ultimately correct the ? ion load
ACID-BASE BALANCE
There are three systems that can help regulate hydrogen ion concentration and pH in body fluids
1. Chemical buffer systems
* Manage the imbalance, and act within seconds
2. Lungs
* Respiration, excretes CO2, act within seconds
3. Kidneys
* Excrete/Reabsorb H+ and HCO3-, act within hours or days
physiological buffers include # and # from above.
The blood chemical buffers provide the first defense against a change in blood pH, but the lungs and kidneys must ultimately correct the hydrogen ion load
BICARBONATE BUFFER SYSTEM
Carbonic acid is formed from the reaction between ? and ? → H2CO3
Enzyme dependent reaction (speed up reaction)
? is formed by the dissociation of
H2CO3 → H+ + HCO3-
This reversible reaction is called the
“? REACTION”
CO2 + H2O ↔H2CO3 ↔ H+ + HCO3-
PIC:
This reaction is favored within * ? *!
Presence of the enzyme CARBONIC ?
(in pic: carbonic anhydrase is an IMP ENZYME for hydration reaction of CO2 reaction with water!!)
BICARBONATE BUFFER SYSTEM
The enzyme ? catalyzes the hydration reaction and is especially abundant:
o Within the ?
o In the walls of the lung ?
o In the epithelial cells of the ? tubules
Carbonic anhydrase
CO2+H2O ↔ H2CO3 ↔ H++HCO3-
BICARBONATE BUFFER SYSTEM
Carbonic acid is formed from the reaction between carbon di oxide and water → H2CO3
Enzyme dependent reaction (speed-up reaction)
bicarbonate is formed by the dissociation of
H2CO3 → H+ + HCO3-
This reversible reaction is called the
“HYDRATION REACTION”(as a H gets added)
CO2 + H2O ↔H2CO3 ↔ H+ + HCO3-
PIC:
This reaction is favored within * erythrocytes*!
Presence of the enzyme CARBONIC ANHYDRASE
(in pic: carbonic anhydrase is an IMP ENZYME for hydration reaction of CO2 reaction with water!!)
BICARBONATE BUFFER SYSTEM
The enzyme CARBONIC ANHYDRASE catalyzes the hydration reaction and is especially abundant:
o Within the RBCs
o In the walls of the lung of alveoli
o In the epithelial cells of the renal tubules
Carbonic anhydrase
CO2+H2O ↔ H2CO3 ↔ H++HCO3-
- we have a tissue here that could be a red skeletal muscle cell, for example, or any cell that is producing CO2 because of its metabolism.
- CO2 goes through the plasma membrane reaching the systemic capillaries (going through all the body parts)
- The CO2 diffuses through the plasma membrane of the red blood cells (Recall: gases can diffuse through the plasma membrane quickly, depending on the concentration)
- once the CO2 diffuses inside the red blood cell, carbonic anhydrase works with water (H2O) to produce carbonic acid.
- once carbonic acid is produced, it gets dissociated as it is a weak acid and forms hydrogen ions and bicarbonate inside of RBC
- now because the bicarbonate needs to go back to the plasma to keep going with the buffering system, it needs to shift back to plasma through chloride (because if I just get bicarbonate out of the cell, then deficit of anions left behind)
anions = AN OX (oxidation is loss of e so anions are - )
- So for the bicarbonate to leave the RBC, needs chlorides to come inside the RBC and thus the CHLORIDE SHIFT occurs (where bicarbonate goes out of RBC, to PLASMA and chloride shifts to RBC)
- the hydrogen ion that is inside of the RBC from the dissociation of carbonic acid will bind to the hemoglobin that is now leaving the oxygen molecule that was carrying it to enter the tissue (left bottom in image)
- Here talking about RBC arriving to tissue, oxygenated
- Once the hemoglobin delivers the oxygen to the tissue, it has more affinity for the hydrogen ion produced from carbonic acid (carbonic acid -> bicarbonate and H+ ion) which in turn has formed due to CO2 that has entered the red blood cell, thus H+ ion binds to the hemoglobin here fomring HHb
- And CO2 is delivered to the tissue so that CO2 can ALSO be carried as a CARBAMINO compound with the hemoglobin HOWEVER, the carbonic acid pathway is the main system.
- So then this red blood cell that gave that oxygen to the tissue, got the CO2 and then converted the CO2 into hydrogen ion and bicarbonate,… is carrying this hydrogen ion with the hemoglobin is going back to the lungs.
- the oxygen that is in the alveoli goes into the RBC and the oxygen has more affinity for the hemoglobin (HHb) so oxygen binds to it and the H ion in HHb (now HbO2) gets released
- then the hydrogen ion (H+) that gets released from HHb is now inside of the red blood cell and needs to pair up with the bicarbonate (HCO3) which is NOT in the RBC but in the plasma.
- For the bicarbonate to enter RBC (Recall: in the previous one leaving RBC) need chloride so CHLORIDE SHIFT occurs again, but in the reverse direction now so chloride LEAVES the RBC and more bicarbonate (HCO3) coming into RBC to BUFFER the hydrogen ion (dumped by haemoglobin i.e. Hb, before HHb) in the RBC
- Law of mass action occurs which diverts the equation (bicarbonate + H) into carbonic acid and so the carbonic anhydrase will then convert carbonic acid (H2CO3) into CO2 and water.
- the CO2 will then go through the RBC membrane to the plasma (pulmonary capillaries) and then to the pulmonary alveoli and then eliminated by the lungs through exhalation
ENSURE U CAN ANSWER THESE QUESTIONS!!
PHOSPHATE BUFFER SYSTEM
Low concentration in ECF compared with ? buffer system
** Very important as an ? buffer (particularly muscle cells) and in the ? filtrate of the ? **
React with acids and bases similar to the ? buffer system
like the bicarbonate buffer system in terms of reacting with acids and bases however will have different weak acid (? phosphate) and conjugate base (? phosphate)
PHOSPHATE BUFFER SYSTEM
Low concentration in ECF compared with bicarbonate buffer system
** Very important as an intracellular buffer (particularly muscle cells) and in the tubular filtrate of the kidneys **
React with acids and bases similar to the bicarbonate buffer system
like the bicarbonate buffer system in terms of reacting with acids and bases however will have different weak acid (dyhydrogen phosphate) and conjugate base (monohydrogen phosphate)
