Term
| What is a substance with the capacity to donate or transfer a proton? |
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Definition
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Term
| Strong acids have a _____ Proton affinity where as weak acids have a ____ proton affinity. |
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Definition
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Term
| What is a substance with the capacity to accept or add a proton? |
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Definition
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Term
| A strong base binds a proton _______, a weak base a proton _______. |
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Definition
*Readily
*In smaller amounts |
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Term
| Is water an acid or a base? |
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Definition
*Water can function as an acid or a base
*it is a weak acid and a weak base, can dissociate into ions - H+ and OH- (Acid), and H3O+ (Base) |
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Term
| A small pK has ________ dissociation where as a large pK has _________ dissociation. |
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Definition
*Little dissociation
*A lot of dissociation |
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Term
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Definition
| *The strength of the acid, a lower pK= increased strength. |
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Term
| True or false, hydrogen ion content in body compartments is very high. |
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Definition
*False, they are very low
*H+ in ECF is 40x 10 (-6) mEq/L
*Concept of pH makes reporting of hydrogen ion concentration easier clinically |
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Term
| What is the definition of pH? |
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Definition
| *Negative logarithm (base 10) of the hydrogen ion concentration |
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Term
| There is little fluctuation in hydrogen ion concentration in healthy patients there for the usual pH range is _______> |
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Definition
*7.38-7.42
*Changing the hydrogen ion concentration > or <40 the pH will change dramatically |
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Term
| What helps maintain the narrow window of pH in the body? |
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Definition
| *Body buffers (renal and pulmonary systems |
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Term
| The renal and pulmonary system help _____> |
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Definition
*eliminate parentally administered, orally ingested and endogenously produced acids
*Net result = surplus of acid |
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Term
| List the normal amounts for: pH, pO2, pCO2, HCO3. |
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Definition
*pH: 7.35-7.45 (7.40)
*pO2: 80-100 (90)
*pCO2: 35-45 (40)
*HCO3: 22-26 mEq/L (24) |
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Term
| How do body buffers keep the pH in balance? |
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Definition
*They accept or donate protons in an effort to stabilize hydrogen ion concentrations- most often bind.
*There are better buffering systems for acids than for bases. This is probably due to the fact that the byproducts of most bodily processes are acids (lactate). |
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Term
| List the five extracellular buffers |
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Definition
*Carbonic acid-bicarbonate
*Reduced and oxygenated hemoglobin
*Plasma proteins
*phosphate
*Na+ pump exchange for K+ and H+ (kidneys) |
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Term
| Which of the five extracellular buffers can change quickly during a case? |
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Definition
| *Plasma proteins d/t bleeding |
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Term
| What is the most important buffer? |
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Definition
*Carbonic acid-bicarbonate
*(HCO3- + H+ <-> H2CO3 <-> CO2 + H2O |
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Term
| What are intracellular buffers? |
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Definition
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Term
| How are intracellular buffers measured? |
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Definition
| *Cant because you can't get into the cell. |
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Term
| If you can't ventilate a patient and the CO2 goes up thus causing the patient to become acidodic, can you give NaHCO3 to improve the problem? |
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Definition
| *No, It will eventually drive the reaction to the right increasing CO2 even more. |
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Term
| Why when looking at the relationship between pH and buffering systems do we look at primarily carbonic acid-bicarbonate buffers? |
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Definition
*Intracellular buffers are poorly understood
*Changes in this buffer system reflect similar changes in other buffers
*More easily calculated (H&H). |
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Term
| What does the H&H equation describe? |
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Definition
| *The relationship between pH and buffering system |
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Term
| How does the body attempt to maintain neutrality according to the H&H equation? |
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Definition
| *By maintaining a ratio of 20:1 |
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Term
| How does pH change with altered neutrality ratios? |
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Definition
*Altered- alters acid-base status
*Increased- alkalosis
*Decreased ratio- acidosis |
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Term
| what is the pK in the hendersen hasselbach equation? |
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Definition
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Term
| How is dissolved CO2 calculated? |
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Definition
| *Dissolved CO2= 0.03 x PaCO2 |
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Term
| What is accounted for and assumed with base excess? |
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Definition
*Intracellular and extracellular buffering components taken into account
*assumes an average buffering capacity of the entire system
*Measurement gages addition or removal of respiratory PaCO2 so as to restore the pH to a normal 7.4. |
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Term
| What is the volume of distribution for bicarbonate? |
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Definition
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Term
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Definition
*The difference between the patient's actual HCO3- and a normal HCO3- at a pH level of 7.4.
*ex: 10 BE= you have 10mEq too much base or -5 = you are acidic and deficient in base |
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Term
| Why is the treatment for a BE divided by 2? |
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Definition
| *To avoid overshooting and causing alkalosis which can decrease oxygen dissociation. |
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Term
| What three things need to be present in order to give HCO3 to treat a negative BE? |
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Definition
*pH <7.2
*pCO2 normal
*absolute value of BE >6
ALL MUST BE PRESENT!! |
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Term
| When is anion gap important? |
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Definition
*When considering metabolic acidosis
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Term
| What is anion gap? How is it calculated? What is normal? |
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Definition
*Difference between unmeasured anions and cations within serum.
*Na+ - (Cl- +HCO3-)
*Normal= 10-12 mEq/L |
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Term
| What is the sole cause of Respiratory Alkalosis? |
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Definition
| * Alveolar Hyperventilation |
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Term
| What are reasons that can lead to respiratory alkalosis? |
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Definition
*Increased mechanical ventilation (most common)
*Central stimulation
*Peripheral stimulation (Pain)
*Unknown mechanisms
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Term
| What are common findings associated with respiratory alkalosis? |
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Definition
*Elevated pH
*Decreased PaCO2 (and HCO3- after compensation)
*Hydrogen ions move out of cells in exchange for K+ (hypokalemia)
*Enhanced binding of calcium to protein decreases calcium concentrations --> Increased neuromuscular irritability, tetany, and seizures
*Decreased cerebral blood flow |
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Term
| If the patient is hypokalemic and has respiratory alkalosis, should supplemental K be given? |
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Definition
| *No, the reaction will reverse after surgery leading to hyperkalemia |
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Term
| What is the cause of respiratory acidosis? |
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Definition
| *Alveolar hypoventilation and increased CO2 production |
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Term
| What are common findings with respiratory Acidosis? |
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Definition
*Carbonic acid-bicarbonate buffer equation driven to Left --> increased H+ and decreased pH
*Right shift of oxyhemoglobin dissociation curve (but tissue hypoxia may still occur)
*Myocardial and smooth muscle depression
*In the awake patient, confusion and unresponsiveness |
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Term
| What is metabolic alkalosis caused by? |
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Definition
| *Increased bicarbonate concentration in plasma |
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Term
| What are causes of metabolic Alkalosis? |
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Definition
*Chloride sensitive= NaCl deficiency and ECF depletion
-ECF depletion clauses renal tubules to reabsorb Na+
-If not enough Cl- available to accompany Na+ then H+ secreted to maintain electroneutrality
*Chloride resistant
- Increased mineralcorticoid activity--> sodium retention--> increased H+ and K+ secretion to maintain electroneutrality |
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Term
| What can cause metabolic acidosis with an elevated anion gap (surplus of acid >10mEq/L)? |
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Definition
*Accumulation of unmeasured ions--> decreases in Cl- and bicarbonate
*Renal failure--> failure to secrete acid
*Lactic acidosis, ketoacidosis, certain medications --> surplus of acid
**Lactic acidosis is the most common severe metabolic acidosis encountered in anesthesia |
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