clinical chem test 2
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- What are 4 metabolic reactions that create acids?
-
1. Carbohydrate - lactic/pyruv.
2. Lipid - try - fa - ketone bod
3. Protein - AA - CO2
4. Nucleic acids - phosphoric - What are 3 types of acids in the body?
-
1. Fixed HPO4, HSO4
2. Organic - lactic acid, etc.
3. Volatile (CO2) - What enzyme catalyzes the carbonic acid - bicarbonate buffer system?
- Carbonic anhydrase
- What are 4 physiologic buffer systems?
-
1. Bicarbonate
2. Hemoglobin
3. Phosphate
4. Proteins -
What is the normal base:acid ratio for body buffering?
What maintains it? -
20:1
Maintained by lungs - How set up henderson-hassel eqn for acid/base physiology?
- ph=6.1 + log(kidney/lung)
- What residue in Hb allows buffering?
-
imidizole - 16/molecule
pKa = 7.3 -
How is inhaled CO2 transported
-in plasma
-in RBCs -
plasma = HCO3-
RBCS = H+ w/ Hb -> HbH - In Lungs, how is Hgb a stronger acid, bound to O2 or unbound?
- Oxygenated - bound.
- Where is the phosphate buffering system important?
- In urine
- What does blood gas msmt tell us?
- how well the cardiopulmonary homeostasis is maintained.
- What are arterial blood gases used to assess?
-
1. Adequecy of oxygenation
2. Adequecy of ventilation
3. Acid-base balance status. -
What are these laws:
-Boyle's
-Charles'
-Guy-Lussac's -
Boyle: P1V1 = P2v2
Charl: V/T = V/T
Guy: P/T = P/T -
What are these laws:
Dalton's
Henry's
Fick's -
D: Total P = sum of partials
F: solubility = Pressure/Temp
H: gas diffusion - What is arterial oxygenation?
- the oxygen in arterial blood
- what does arterial oxygenation depend on?
-
1. Fraction of inspired O2
2. Ventilation of alveoli
3. Diffusion across alveolar/capillary membrane.
4. O2-carrying capacity of blood. - In what 2 forms does O2 transport in blood?
-
Dissolved in plasma = 3%
Bound to Hb = 97% - What is dissolved o2 important for?
- cellular oxidative processes
- Which fraction of O2 changes the oxyhb dissociation curve?
- dissolved
-
How do increases affect the O2-Hgb dissociation curve?
pH, CO2, Temp, CO, 23DPG, HbS, HbF, Young/old hb? -
pH incr, left
CO2 incr, right
Temp, right
CO, left
23DPG, right
HbS/young, right
HbF/old, left - What does the blood oxygen content represent?
- Actual amount of O2 in blood, dissolved + bound to Hb.
- What is the p50 in a right/left shift?
-
Right shift: >27 torr
Left shift: < 27 torr - What measurement tells if the tissue O2demand is being met?
- O2 Content - NOT pO2
-
What is Hypoxemia?
Hypoxia? -
Decr. O2 content of blood.
Decr. O2 supply to tissue. - How does hypoxia affect body pH?
- Causes acid to increase because of switch to anaerobic cellular metabolism.
- What are 4 classes of Hypoxia?
-
1. Arterial (low arterial O2)
2. Anemic (low O2 carry capac.)
3. Circulatory (bad circulation)
4. Histotoxic (bad utilization) - What is the most physiologically reflective blood gas measurement of oxygenation?
- pCO2
- What determines the pCO2?
- Metabolism
- in what 3 basic forms is CO2 carried in blood?
-
1. Dissolved in plasma
2. Carbamino compounds
3. Bicarbonate ions - What happens to dissolved CO2 in plasma?
- It combines with water to form carbonic acid then H+/HCO3-
- What's normal ratio CO2:H2CO3?
- 1000:1
- How does CO2 form carbamino compounds?
- By complexing with N-terminal side groups of amino acids.
- What diffuses in exchange for HCO3- from RBCs?
- Chloride ions
- What is the physiological pH reference range?
- 7.35-7.45
- What are 5 examples of things that can cause a respiratory acidosis?
-
1. Bad respiratory center
2. Defective nerves/muscles
3. thoracic cage disorder
4. airway obstruction
5. pulmonary disease - At an initial respiratory acidosis, what is HCO3-?
-
In reference range. Then it increases, compensate for acid.
If no compens, it decreases. - What are 4 effects a decreased pH has on metabolism?
-
1. Altered proteins
2. Right shift for Hemoglobin
3. lung blood vessels constrict
4. Heart contractility decrease - what are 5 things that can cause a respiratory alkalosis?
-
1. response to hypoxis
2. drugs and toxins
3. CNS disorders
4. Psychogenic hyperventilation
5. reflex stim of respiration - What is the compensation mechanism for resp acidosis?
- Increase renal excretion of acid, reabsorption of bicarb. Takes several days, no full comp
- What is the compensation mechanism for resp alkalosis?
- Decr. H+ excretion, bicarb reabsorption.
- What causes metabolic alkalosis?
-
vomiting
eating bicarb (antacids)
depleted potassium
diuretics -
-What is the anion gap, and how do you calculate it?
-What should it be? -
Difference btwn unmeasured anions/cations: (Na+K)-(CL+HCO3)
Should be 17 or lower. - What does the BE tell us?
- Base excess - positive indicates excess, negative indicates deficit.