Glossary of 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?
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: P1V1 = P2v2
Charl: V/T = V/T
Guy: P/T = P/T
What are these laws:
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?
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?
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?
What determines the pCO2?
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?
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?
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?
eating bicarb (antacids)
depleted potassium
-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.

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