Acid Base 1 Flashcards
What is a normal [H+] in the blood?
40 nEq/L
If take the -log of this value, get 7.4ish –> where normal blood pH determination comes from
What is the range of normal blood pH?
What is the definition of acidemia and alkalemia?
7.37 - 7.42
Acid: pH < 7.37
Alkalosis: pH > 7.42
Many proteins are [acids or bases].
Bases
What is the pH in the following locaitons in the body?
pH < […] or pH > […] is incompatible with life.
- 8
- 0
- What are 3 common sources of “acid production” in the body?
- How are each of these sources of acid secreted?
- CO2 (CO2 + H2O <=> H2CO3 <=> H+ + HCO3-) –> exhaled
- From diet (sulfuric and phosphoric acids) –> buffered and secreted in kidney
- Lose HCO3- in stool –> loss of base is equivalent to gain of acid –> buffered and secreted in kidney
- Is H2CO3 a strong or weak acid?
- Is there more H2CO3 or H+ in the blood?
- Weak
- H2CO3
How much acid is produced/ingested daily?
-80mEq
What are the immediate buffering compounds in the extracellular fluid? (Blood)
HCO3-
HPO4-2
What compounds act as buffers in the intracellular fluid?
Organic phosphates
Proteins
Hemoglobin
What are all the ways that we can buffer changes in pH?
Where in the body is carbonic anhydrase concentration high?
- renal tubule epithelial cells
- walls of alveoli
- RBC
What is the definition of a buffer?
How can you manipulate the hendersen hasselbach eqn to relate to the bicarbonate buffering system using pCO2 and [HCO3-]?
pCO2 levels are controlled by the […] and HCO3- levels are controlled by the […]
Lungs
Kidney
Metabolic acidosis and metabolic alkalosis are driven by what?
[HCO3-]
Low [HCO3-] leads to increasing [H+] and thus decreasing pH (acidosis)
High [HCO3-] leads to decreasing [H+] and thus increasing pH (alkalosis)
Respiratory acidosis and alkalosis are driven by what?
pCO2
High pCO2 –> increases [H+] –> decreases pH
Low pCO2 –> decreases [H+] –> increases pH
In acute respiratory acidosis, what do the tissues do to buffer the increasing CO2?
Increasing pCO2 –> increasing [H+] –> respiratory acidosis –> CO2 can enter tissues and be acted upon by carbonic anhydrase if the tissue has that enzyme and broken down ultimately into H+ and HCO3-. H+ can bind to Hb to be buffered and HCO3- enters blood to buffer excess H+ in blood from increasing CO2.
In chronic respiratory acidosis, what does the body do to try and keep the blood pH from being too low?
Increase reabsorption of HCO3- from the urine and increase excretion of H+ in the urine
In acute respiratory alkalosis, what do the tissues do to buffer the decreasing CO2?
Decreasing pCO2 –> decreasing [H+] –> respiratory alkalosis –> H+ in tissues can combine with HCO3- in tissues to form H2CO3 which can then be converted to CO2 via carbonic anhydrase in tissues. This generates more CO2 to prevent the pH from rising too high (decreases drive of le chatlier’s principle to push eqn to left)
In an acute respiratory disturbance, the buffering occurs […] whereas in a chronic disturbance the buffering occurs […]
Intracellularly
By the kidneys
What is the difference between metabolic acidosis and respiratory acidosis?
Metabolic - adding H+ to blood (food, loss of HCO3- in stool)
Respiratory - caused by changes in breathing that thereby alter the pCO2
In metabolic acidosis, how does the body prevent pH from dropping too low?
Immediately, the increasing H+ is buffered** by the bicarb buffer system (Combines with HCO3- to make H2CO3 and then that’s converted to CO2). Within minutes - hours, will start to hyperventilate because increasing CO2 triggers chemoreceptors in carotid body/aortic body and central system to increase respiration rate. This is the **compensation that occurs by the lungs.
In metabolic alkalosis, how does the body prevent the pH from rising too much?
Can be caused by vomiting (loss of H+ from stomach). Immediately, the decreasing H+ is buffered by the bicarb buffer system (CO2 in blood will be driven to form H+ and HCO3-). Within minutes - hours, will start to hypoventilate because decreasing CO2 triggers chemoreceptors in carotid body/aortic body and central system to decrease respiration rate. This is the compensation that occurs by the lungs. This will increase CO2, drive eqn back to right to replenish H+ and HCO3-. Overtime, this can lead to a build up of HCO3- since you only lost H+ but that can be compensated for by the kidneys.
For every 1 mEq/L drop in [HCO3-] (and thus also H+), what is the expected compensation by the lungs?
decrease pCO2 by 1.5mmHg
Phosphate Buffer System
- Where is this buffer system most active?
- Manipulation of henderson hasselbach for this buffer system?
