Acid-Base - Pt 1 Intro Flashcards
Bicarbonate levels in the blood are [].
24 mEg/L
PaCo2 in arterial blood is []
40 mmHg
[H+] in blood is []?
40 nEq/L
Only the [] [] concentration contributes to pH. That which is bound to any [], chemical (proteins etc) oranything has [] contribution to the pH
Only the Free H+ concentration contributes to pH. That which is bound to any buffer, chemical (proteins etc) or anything has zero contribution to the pH
A hydrogen ion (H+) is a single [] [] released from a hydrogen atom
free proton
Easy definitions:
- Acid = proton []
- [] [] is more likely to give up a proton. [] is a good example.
- [] [] is less likely to give up a proton. [] [] is a good example
- Acid = proton donor
- Strong acid is more likely to give up a proton. HCl is a good example.
- Weak acid is less likely to give up a proton. Carbonic acid is a good example
Extreme conditions of [H+]:
- 10 nEq/L….pH ~ []
- 160 nEq/L…pH ~[]
- 10 nEq/L….pH ~ 8
- 160 nEq/L…pH ~6.8
pH is [] related to the [H+].
inversely
- Normal pH of blood is [] +/- .02
- Acidosis occurs at a pH less than []
- Alkalosis occurs at a pH greater than []
- Normal pH of blood is 7.4 +/- .02
- Acidosis occurs at a pH less than 7.38
- Alkalosis occurs at a pH greater than 7.42
- Volatile acids are defined as [] that may be eliminated by the [].
- Example: []
- Volatile acids are defined as gases that may be eliminated by the lungs.
- Example: CO2
Fixed Acids:
- Acids which result from [] of sulfur or phosphate containg amino acids, phospholipids, nucleic acids, phosphoporteins and phosphoglycerides
- Primarily [] (H2SO4) and [] acid (H3PO4).
- Acids which result from metabolism of sulfur or phosphate containg amino acids, phospholipids, nucleic acids, phosphoporteins and phosphoglycerides
- Primarily sulfuric (H2SO4) and phosphoric acid (H3PO4).
Organic Acids:
- Comes from ordinary [] such as lactic, pyruvic, ketones during oxygen [], shock, and []
Comes from ordinary production such as lactic, pyruvic, ketones during oxygen debt, shock, and exercise
- There are 3 regulatory systems that interact to control body pH
- [] buffering system
- [] Responses
- [] [] Responses
- There are 3 regulatory systems that interact to control body pH
- Chemical buffering system
- Respiratory Responses
- Renal System Responses
What are the 4 major physicoChemical Buffers?
Bicarbonate
Phosphate
Ammonia
Proteins
The respiratory response will attempt to move pH back toward []but will always remain [], due to feedback [] and receptor [] and functionality.
The respiratory response will attempt to move pH back toward normal but will always remain incomplete, due to feedback inhibition and receptor sensitivity and functionality.
Kidneys respond to pH via several mechanisms
- Increased [] of H+/HCO3- into the urine
- Increased [] of H+/HCO3- into the blood
- [] [] H+ cellular secretory transport mechanisms
- [] [] HCO3- cellular secretory transport mechanism
- Make New []
- Increased secretion of H+/HCO3- into the urine
- Increased reabsorption of H+/HCO3- into the blood
- Up/Down regulate H+ cellular secretory transport mechanisms
- Up/Down regulate HCO3- cellular secretory transport mechanism
- Make New HCO3-
Normally, it doesn’t matter where the H+ comes from, it’ll always bind to [] if available.
bicarbonate
- pH and bicarbonate have a [] relationship. When [Bicarbonate] increases, pH []
- pH and CO2 have an [] relationship. When [CO2 increases, pH []
- pH and bicarbonate have a direct relationship. When [Bicarbonate] increases, pH increases
- pH and CO2 have an indirect relationship. When [bicarbonate] increases, pH decreases
The optimum effect of a buffer occurs at the [] point of a titration curve. This is also the [] of the buffer - or its dissociation constant.
The optimum effect of a buffer occurs at the inflection point of a titration curve. This is also the pK of the buffer - or its dissociation constant.
- Bicarbonate’s optimum pK is [] +/- 1 unit at a normal pH of 7.4
- However, this optimum pK falls under our normal body’s pH of 7.4, which is why bircarb is not the most [] buffer in our body.
- Bicarbonate’s optimum pK is 6.1 +/- 1 unit at a normal pH of 7.4
- However, this optimum pK falls under our normal body’s pH of 7.4, which is why bircarb is not the most powerful buffer in our body.
Buffering Power is based on 2 things:
- Buffering of a solution is [] when the pH of the solutin is at or near the [] of the buffer
- Or +/- one pH unit from the pK
- [] of the buffering sibstances…The more buffer, the better
- Buffering of a solution is greatest when the pH of the solution is at or near the pK of the buffer
- Or +/- one pH unit from the pK
- Concentration of the buffering sibstances…The more buffer, the better
- The most important buffering system in the body is the [] [] []
- This is becuase both elements are []systems.
- The lungs can [] CO2
- The kidneys can [] Bicarb/H+
- The most important buffering system in the body is the Bicarbonate Buffer System
- This is becuase both elements are open systems.
- The lungs can expire CO2
- The kidneys can micturate/save Bicarb/H+
In normal body conditions, the bicarbonate buffering system cannot be [] to one extreme of the system or the other.
pushed
The HCO3- buffering system links together [] buffering, the [] system and the [] system in the regulation of body pH
The HCO3- buffering system links together chemical buffering, the respiratory system and the renal system in the regulation of body pH
Phosphate Buffer System:
- components are [] (dibasic phosphate) and [] (Monobasic phosphate)
- the pK is [] which is relatively close to body pH, so this system is more []than bicarbonate.
- However, [] levels are low so its not as important as bicarbonate
- components are HPO42- (dibasic phosphate) and H2PO4- (Monobasic phosphate)
- the pK is 6.8 which is relatively close to body pH, so this system is more powerful than bicarbonate.
- However, extracellular levels are low so its not as important as bicarbonate
The phosphate buffering system is important in regulaitng [] pH.
Intracellular
Phosphate buffering is very important withint the [] [] of the kidney.
Distal tubules
The [] [] system is the most powerful buffer system of the body.
protein buffer
The respiratory system regulates body pH by increasing or decreasing [] in the blood.
The respiratory system regulates body pH by increasing or decreasing [CO2] in the blood.
Doubling ventilation [] the pH only slight, because it increases breathing ate which [] CO2 in teh blood
Doubling ventilation increases the pH only slight, because it increases breathing rate which decreases CO2 in teh blood
Halving the ventilation [] the pH only slightly by slowing respiration which causes an [] in CO2 in the blood.
Halving the ventilation decreases the pH only slightly by slowing respiration which causes an increase in CO2 in the blood.
[] sense changes in pH and via reflexes initiate correct changes in ventilation
Chemoreceptors
The respiratory system effectiveness ranges from []%. It can never fully return pH to its normal levels.
50 - 75%
The kidneys regulate pH primarily by increasing or decreasing [] in the body fluids
The kidneys regulate pH primarily by increasing or decreasing [HCO3-] in the body fluids
- Nonvolatile acids come primarily from the metabolism of [].
- Approximately [] mEq/day are formed
Proteins
80 mEq/L
- The kidney filters roughly [] of bicarbonate.
- Also has to secrete [] of nonvolatile acids.
- So the total H+ load if []
- The kidney filters roughly 4320 mEq/day of bicarbonate.
- Also has to secrete 80 mEq/day of nonvolatile acids.
- So the total H+ load of 4400 mEq/day.
What are the three fundamental mechanisms of homeostasis regulated by the the kidneys?
Secretion of H+
Reabsorption of HCO3-
Production of “New HCO3-
- 80-90% of daily HCO3- reabsorption happens in the [] []
- 10% of daily HCO3- reabsorption happens in the [] [] []
- 5% of daily HCO3- reabsorption happens in the [] and []
- 80-90% of daily HCO3- reabsorption happens in the Proximal Tubule
- 10% of daily HCO3- reabsorption happens in the Thick ascending limb
- 5% of daily HCO3- reabsorption happens in the Distal Tubule and Collecting Duct
- The [] [] is responsible for 85% of H+ secretion from the [] membrane of PCT cells
- T/F - this exchanger uses ATP
- This exchanger draws [] into the cell down its concentration gradient while secreting H+
- The NA+/H+ Exchanger is responsible for 85% of H+ secretion from the apical membrane
- FALSE - Secondary Active transport, so no ATP
- This exchanger draws sodium into the cell, down its concentration gradient while secreting H+
10% of H+ secretion is performed by the [] on the [] membrane of PCT cells.
10% of H+ secretion is performed by the H+-ATPase on the apical membrane of PCT cells.
Around the PCT, filtered [] combines with H+ to reform CO2 and H2O via [] [] [] carbonic anhydrase
Around the PCT, filtered HCO3- combines with H+ to reform CO2 and H2O via apical brush border carbonic anhydrase
- Cellular HCO3- transport across the basolateral membrane is facilitated by 2 transportes, what are they?
- Are these transporters active transporters?
- Transporters
- NBC1; Na+/HCO3-….Co-transporter
- AE1; Cl-/HCO3-…..Anion exchanger
- No, these are not active transporters.
For every HCO3- reabsorbed a H+ is secreted in a [] ratio.
1:1
