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Amt of pressure one gas contributes to total pressure
Partial pressure
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Air is made of 79% ____ and 21% ____
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P-air = ___ mm Hg
P-N2 = .79 x ___ mm Hg = ___ mm Hg
P-O2 = .21 x ___ mm Hg = ___ mm Hg
- 760 mm Hg
- 760; 600
- 760; 160
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Both ___ and ___ gases exert a partial pressure
vaporized and dissolved (in liq)
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Over time what happens to PP and concentration of O2 and CO2 in water and air?
- PP becomes the same
- Concentration of CO2 is higher in water than in air (and is also more soluble in water than O2)
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How does a partial pressure of a gas affect the movement of that gas?
In gas mixtures, they move down OWN PP gradient from high to low PP
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In general, how do the partial pressures of carbon dioxide and oxygen change throughout the cardiovascular circuit?
As go from arteries to tissues to veins, decrease in conc of O2 while CO2 is opposite
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What are the numerical values for partial pressures in arterial and mixed venous blood?
(Systemic arteries, systemic veins, pulmonary arteries, pulmonary veins)
- Systemic veins & pulm arteries (deO2 blood):
- PP-O2 = 40 mmHg
- PP-CO2 = 46 mmHg
- Systemic arteries & pulm veins (O2 blood):
- PP-O2 = 100 mmHg
- PP-CO2 = 40 mmHg
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In what forms is oxygen transported in the blood? How is the majority of oxygen transported in the blood?
Dissolved in plasma, but most is transported via hemoglobin
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Where is oxyhemoglobin formed?
What does the formation of oxyhemoglobin involve? (& bk to hemoglobin)
In lungs, as O2 molecs go from alveolar air to capillary blood, they bind to hemoglobin, forming oxyhemoglobin. When blood reaches tissue, O2 molecs dissociate from hemoglobin & diffuse into cells
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Hemoglobin can bind up to ___ O2 molecs. In arterial blood, hemoglobin has ___ of ___ O2 molecs bound (__%), but in venous blood, hemoglobin has ___ of ___ O2 molecs bound (___).
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What does the saturation of hemoglobin tell us about pressure of O2?
Arteries are more O2 saturated, so have higher PP of O2 than veins
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What does the oxygen dissociation
curve show us?
- Shows how much O2 is associating w/hemoglobin;
- As P-O2 increases (X-axis), binding increases (Y-axis) (associating increases) (less unloading of O2)
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What do changes in temperature and pH do to this curve? How does this affect oxygen unloading?
Increased temp & pH cause curve to shift right; more oxygen unloading
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How does carbon monoxide affect binding of oxygen to hemoglobin?
More carbon monoxide means less O2 binding b/c hemoglobin has greater affinity for carbon monoxide
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How is carbon dioxide transported in the blood, and what are the relative proportions of each mode of transport? (3)
- Dissolved in blood (in plasma): 5-6%
- Dissolved as bicarbonate (H2CO3): 5-8%
- Bound to hemoglobin (carbaminohemoglobin): 86-90%
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Enzyme which converts CO2 and water to carbonic acid (H2CO3). How does the law of mass action affect this enzyme?
Carbonic anhydrase; an increase in CO2 causes an increase in bicarbonate (HCO3-) and H+ ions (formed from H2CO3)
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An increase of CO2 in blood causes increase in ____ concentration in blood
carbonic acid (HCO3-)
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In ___ to ___, carbonic anhydrase converts CO2 to HCO3-
In ___ to ___, carbonic anhydrase converts HCO3- to CO2
- Tissues to blood
- Blood to lungs
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How does the partial pressure of oxygen affect the amount of carbon dioxide that can be dissolved in the blood?
Higher PP of O2, amt of CO2 dissolved in bloodstream is lower (& vice versa)
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Why is diffusion b/w alveoli and blood rapid? Where does most exchg occur in capillaries?
- B/c small diffusion barrier and lots of alveoli means large surface area
- Most exchg occurs in first 1/3 of capillary length
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What is mixed venous blood?
Blood in pulmonary artery that contains blood returned to the heart from the systemic veins
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How do the partial pressures of carbon dioxide and oxygen in mixed venous blood differ from venous blood coming from a working (metabolically active) tissue?
PP of mixed venous blood is normally 40 mmHg for O2 and CO2 is 46 mmHg, but in working (metabolically active) tissue, P-O2 decreases, and P-CO2 increases
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What things affect the partial pressures of alveolar oxygen and carbon dioxide? (3)
- P-O2 and P-CO2 of inspired air
- Minute alveolar ventilation
- Rates at which respiring tissues use O2 and produce CO2
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Breathing is controlled by motor neurons in respiratory muscles. Inspiration uses motor neurons of the ____ and expiration uses motor neurons of the ____.
- External intercostal muscles
- Internal intercostal neurons
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How is the activity of the inspiratory muscles different in quiet versus active ventilation? Expiratory?
During active ventilation, inspiratory muscle tension cycles are larger b/c more action potentials, and lung volume is increased. The expiratory muscles are normally inactive during quiet vent, but during active vent, they become active.
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Detect blood levels of O2 and CO2
Chemoreceptors
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What are the 2 types of chemoreceptors and where are they located?
- Peripheral: carotid bodies
- Central: medulla oblongata
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Peripheral chemoreceptors are located in ____ and respond mainly to chgs in ___. Central chemoreceptors are located in ___ and respond mainly to chgs in ___.
- Carotid bodies of carotid sinus; pH
- Medulla oblongata; pH of CSF (cerebral spinal fluid)
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Normal blood pH is ___ to ___. ____ & ____ systems regulate blood pH, and chgs can alter ____.
- 7.3-7.42
- Resp & renal
- protein activity
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What is respiratory acidosis pH and effects?
What is respiratory alkalosis pH and effects?
- Acidosis: <7.35; causes depression of CNS
- Alkalosis: >7.45; causes over-excitation of CNS
(don't need to know #s)
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How is hyperventilation corrected? What causes it?
Decreases in the rate and depth of breathing due to decreased amt of CO2 (P-CO2)
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__ = rate of air flow
__ = rate of blood flow
- ventilation (VA)
- perfusion (Q)
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What is ideal ventilation-perfusion ratio?
1; b/c they should match eachother
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How do we respond to a decrease in ventilation? (b/c there's more CO2 and less O2 in blood, how are bronchioles and pulmonary arteries affected?)
there is increased P-CO2 in bronchioles, which causes bronchodilation, which allows more air in; and there is an decrease in P-O2 in pulm arteries, which causes vasoconstriction
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How do we respond to a decrease in perfusion? (b/c there is more O2 and less CO2 in blood, how are bronchioles and pulmonary arteries affected?
there is a decreased P-CO2 in bronchioles, causing bronchoconstriction; and there is an increase in P-O2 in pulm arteries, which causes vasodilation (better gas xchg)
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