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The MCAT-BIO

PHYSIOLOGICAL BUFFERS & GAS EXCHANGE

QuestionAnswer
What is physiological pH? 7.4
respiratory acidosis retention of CO2
respiratory alkalosis loss of CO2
metabolic acidosis loss of HCO3
metabolic alkalosis loss of H3O
How does blood compensate for reduced uptake of oxygen? increase heart rate and make more blood cx
What kind of rxn is the binding / releasing of oxygen from Fe? redox
What does myoglobin do? Does it have quaternary structure? -transfers oxygen from hemoglobin to muscle cell -no
How many oxygens can myoglobin bind to? one
Does myoglobin exhibit cooperativity and Bohr effect? NO
How is CO2 carried through blood? 1. physical solution (plasma) 2. bicarbonate ion (RBC) 3. combined with hemo (carbamino cpds)
How to form bicarbonate? CO2 enters RBC - meets carbonic anhydrase - combines with water to form carbonic acid - bicarbonate
Does gas exchange require ATP? NO --> passive process
Pulmonary arteries turns into pulmonary ______ in the lungs. capillaries
How can respiratory system adjust to high altitudes? 1. breathe rapidly 2. make more RBC 3. develop more blood vessels 4. alter binding of hemo and oxygen
polycythemia making more RBC
What is the oxygen pressure that enters lungs vs. pressure in alveoli? 40 mmHg vs. 105 mmHg
Do we breathe out bicarbonate? NO! Reverse rxn occurs in alevoli to produce CO2
To balance electrostatic forces, what moves out of cx when bicarbonate is formed? chloride
What is a buffer? acid/base sponge that soaks up excess H+ or OH-
How does kidney fit into balance of carbon dioxide in blood? increase / decrease amt of bicarbonate ion secreted into nephron
What is the shape of the O2-dissociation curve? sigmoidal
What does the O2-dissociation curve depend on? CO2 pressure, pH, temp, and 2,3-DPG
Why is the shape of the O2-dissociation curve sigmoidal? positive cooperativity in hemo
What does a right shift mean? at the same pressure of oxygen, less oxygen will be bound to Hb --> lower hemo's affinity for oxygen
What causes a right shift? -increase in partial pressure of CO2 -decrease in pH -increase in temp -2,3-DPG (CADET)
What does a left shift mean? at the same pressure of oxygen, more oxygen will be bound to Hb
What causes a left shift? carbon monoxide and fetal hemoglobin
Does oxygen or carbon monoxide have greater affinity for Hb? Carbon monoxide! --> 200 times stronger
torpor energy conservation by having decreased arousal
aestivate vs. hibernate torpor during warm months vs. cold months
Haldane Effect oxygen-saturated Hb has reduced affinity for CO2 -facilitates transfer of CO2 from blood to lungs, tissues to blood
When hemo is attached to O2, is it reduced or oxidized? reduced
How does reduced hemo (hemo with O2) act as a blood buffer? accepts protons
Bohr Effect increasing conc. of protons and CO2 will reduce hemo's affinity for O2
How does bicarbonate in RBC turn back into CO2 in lungs? In lungs, binding of O2 to Hb causes release of protons which combine with HCO3
How does Hb know to get rid of oxygen? -CO2 formation (aerobic) -lactic acid formation (anaerobic) --> greater effect
Under acidic conditions, how does Hb release O2? protons bind to Hb and causes release of O2
How does oxygen curve look for myoglobin? linear --> no cooperativity and one subunit
What does fetal curve look like? shifted left and up -at same pressure of O2, more O2 will be bound to Hb
What brain structure is involved in respiration? medullar
What receptors monitor breathing rate? chemoreceptors for oxygen and CO2
What happens to breathing rate when acidosis? body increases breathing rate to expel CO2 and raise pH
Carbonic Acid / Bicarbonate Buffer Eqn CO2 + H2O --> H2CO3 --> H+ + HCO3-
Why is bicarbonate impt for maintaining homeostasis? -excess protons can combine with bicarbonate and turn into CO2 to be expelled (maintains pH) -forms acid in stomach -neutralizes pH of chyme leaving stomach and entering small intestine
What is the predominate form CO2 is carried through the body as? bicarbonate
Where is carbonic anhydrase located? inside RBC
When bicarbonate from plasma enters RBC, what leaves? chloride
Does pH decrease / increase when bicarbonate leaves? decreases
Haldane effect: High O2 vs. low O2 -high O2: enhanced unloading of CO2 -low O2: promote loading of CO2 onto hemo
Haldane Effect vs. Bohr Effect -haldane: describes how O2 determines hemo's affinity for CO2 -Bohr: describes how CO2/H affect hemo for O2
In lungs, high oxygen levels, does hemo affinity for CO2 decrease / increase? decrease
Where does phosphoric acid come from? nucleic acid and phosphopx breakdown
Can px act as buffers? YES --> can absorb excess H+ (esp. amino and carboxyl groups)
Phosphate Buffer Eqn H3PO4 -> H+ + H2PO4 -> H+ + HPO4 -> H+ + PO4 (H2PO4 / HPO4 is the main buffering region)
Why is fetal circulation complicated? non-functional lungs and liver
Created by: 507935299 on 2012-07-09



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