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Only 3 % of oxygen is in solution (blood), the rest is bound to ___
Hemoglobin (Hb) = HbO2
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Hb has a very strong affinity for ___
Oxygen
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At oxygen concentration of the alveolar air, 97.5% of Hb is in the ___
HbO2 form
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"oxygen affinity" means how readily the Hb molecule binds___
O2
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___will affect the saturation of oxygen
Oxygen affinity
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As pO2 rises the saturation of Hb with oxygen ___
Rises
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Bohr Effect: As the pH of blood decreases the affinity of Hb for oxygen(Hb saturation)___
Decreases
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Enzyme responsible for Bohr Effect
Carbonic Anhydrase
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As tempeature rises, Hb will release ___ oxygen
More
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Only 7 % of CO2 is transported as dissolved gas, remaining diffuses into the ___
Red blood cells
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CO2 molecules bind NH2 in the RBCs (storage form-approx. 23% stored in this form)
CarbAminoHemoGlobin formation
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Carbonic Acid formation via enzyme is ___
Carbonic Anhydrase
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CO2 is "tied up" as HCO3-, and hydrogen ions will be buffered by
Hemoglobin molecules
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HCO3- (bicarbonate ion) will diffuse across the cell membrane, in exchange for an chloride ion (Cl-); a COUNTERTRANSPORT called the
- "Chloride shift"
- Hydrogen ions are buffered in the RBC (by Hb and others), but will also diffuse out of the cell driving
- PH down
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Why is it more difficult to breathe on a hot humid day?
- pO2 down because pH20 is up
- Temp is up, gases move faster, so a 3 liter volume of air contains less gas.
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Regulation of respiration is required because the rate of oxygen use and carbon dioxide production at tissue level is not always equal to the
Removal and delivery of these gases at the lungs' surfaces
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Regulatory Centers located in the ___ will regulate activity of respiratory muscles
Pons and Medulla
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Medulla/Rhythmicity Centers: DRG and VRG (Dorsal and Ventral Respiratory Groups)
- "Quiet respiration" controlled here; the inspiratory muscles are stimulated, expiratory muscles are inactive
- Is rhythm-generating and sets the pace
- Stimulation would quicken the Respiratory Rate (RR)
- EUPNEA = normal respiratory rate and rhythm
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Pons/Pontine Respiratory Group = PRG
- Modifies activities of the DRG and VRG centers by inhibitory effects on these centers…creates an end to inspiration and allows expiration.
- Establishes normal respiratory cycles = 1 inhalation & exhalation
- Control of Resp. Regulation Centers:
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Higher Brain Center
Influence PRG via Hypothalamus & Cerebral Cortex
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Hypothalamus:
Emotional or painful responses
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Cerebral Cortex:
Voluntary control
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Temperature Control:
An increase will accelerate RR. Decrease slows RR
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Stretch receptors – on lungs, stimulate
"Inflation reflex",
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Increase vol. of lungs will INHIBIT inspiratory centers (DRG/VRG) of medulla
Via Vagus nerve
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Baroreceptors (carotid and aortic)
- Where an incr. in BP is followed by declining RR
- And a decrease in BP is followed by increased RR
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Chemoreceptors (carotid and aortic bodies)
- Sensitive to pO2 and pCO2 in arterial blood
- Medulla floor- sensitive to CO2/pH of CSF
- Only sensitive to pCO2 of CSF (actually pH-sensitive)
- Under normal conditions, only pCO2 will affect respiratory centers via Chemoreceptors
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Protective Reflexes:
Usually due to exposure to chemicals, toxins, or mechanical stimulation of the respiratory tract (ex. sneezing, coughing),
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“Apnea" is usually evident by
(Respiration. stops briefly)
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