2.13 principles of gas exchange and control of respiration
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Factors affecting gas exchange) Respiratory Membrane: thickness of respiratory membrane (2)
Gas must pass through fluid and cell membranes
.5 microns is healthy girth
Factors affecting gas exchange) Respiratory Membrane: surface area
-70 square meters per lung of alveolar surface area
Factors affecting gas exchange) partial pressures: Daltons law
Total pressure of gas in chamber is defined as the sum of each individual gas pressure
What does Delta PO2 mean?
Alveolus higher than arriving blood
What does delta PCO2 mean?
Arriving blood higher than alveolus
Diffusion gfradeitns ) Alveolus vs Alveolar capillary : details (3)
-alveolar pO2 = 104 mm hg
-capillary blood arriving @ alveolus has pO2 = 40 mm hg
-so therefore, O2 will diffuse into capillary blood bc its lower in content
Diffusion gfradeitns ) systematic capillary vs the cell (3)
-arriving capillary PO2 is 104
-Cell PO2 is 40
-therefore O2 is going to flow into the cell
Diffusion gfradeitns ) Systematic capillary vs the cell
-arriving cap pco2 is 40
-cell pco2 is 45
-therefore the co2 will flow into the arriving cap bc of lower content
Diffusion gfradeitns ) pulmonary cap vs the alveolus (3)
-arriving cap pco2 is 45 mmhg
-alveolar pco2 is 40 mm hg
- -therefore the co2 will flow into the alveolar
- *it gets exhaled
Transport of respiratory gases in blood) O2: (2)
-1.5% dissolved in plasma = Po2
-98.5 % bound to hemoglobin
Transport of respiratory gases in blood) O2: Binding formula or Hemoglobin + O2
Hg + O2 -> Hbo2
Transport of respiratory gases in blood) O2: what's positive comparability ?
- When 1 O2 binds with hemoglobin, the rest of O2 will have easier time to bind because it keeps changing the configuration of hemoglobin every time O2 binds
- *this is how o2 can bind to Hb
What does hemoglobin disassociation curve show?
Description of O2 loading and unloading @ lungs and tissues
hb disassociation curve) As we go into systematic circulation (2)
Po2 drops & concentration of Hb drops also
hb disassociation curve) what percent of O2 do we remove as we go from lungs to tissues?
Is there a fair amount of oxygen in deoxygenated blood? Why? Why not?
Yes there is because we only use up 25% of O2 during one cycle of blood around the body so we have 75% left over
What is the Bohr effect?
- The shifting of usage in co2 from normal arterial carbon dioxide
- *decreased or increased
5 factors that affects the normal arterial CO2
To the left side shift: (5)
To the right (5)
To the left signifies
- Cooler body temp
- *unload its O2 more slowly bc it probably indicated you're resting so no nee for extra o2
To the right signifies
Warmer body temp thus increased CO2
-7-10 % dissolved in plasma = pCO2
-20-30% bound to hemoglobin
CO2) formula in hb
hb + co2 <-> HbCO2 + O2
CO2) what's the carbonic anhydrase reaction?
Making hb and H2O (in blood) into carbonic acid
CO2) what happens to carbonic acid (2)
Becomes bicarbonate and hydrogen ion
CO2) 60% of CO2 is transported in
CO2) what's chloride shift?
-chloride enters while bicarbonate leaves cell to maintain balance of charges
Control of respiration) 2 types of controls
-neural and chemical mechanisms
Control of respiration) Neural mechanisms : controlled by
Control of respiration) Neural mechanisms: Medullary respiratory groups, 2 of them
Control of respiration) Neural mechanisms: 2 of them
Medullary respiratory groups
Control of respiration) Neural mechanisms: Sends signals to (2)
Control of respiration) Neural mechanisms: Pons respiratory center (2)
Controls VRG & DRG
Control of respiration) Neural mechanism: Pontine respiratory group (2)
- Limits length of inspiration
- *prohibits from going past normal levels
Respiratory rhythm) where are pacemaker neurons found in?
Found in VRG
Respiratory rhythm) pre-botzinger complex
Groups of cell that control innate respiration
Respiratory rhythm) pacemaker neurons have
- Sodium and possibly calcium current
- *like heart PM
Chemical regulation of respiration ) chemoreceptor can be found in (2)
peripheral= carotid and aortic bodies
Chemical regulation of respiration ) what type of receptors do they use?
Chemical regulation of respiration ) what is the medulla sensitive to?
Chemical regulation of respiration ) what are the cortid and aortic bodies sensitive to? (2)
CO2 and O2
Medulla PCO2) process (3)
- as CO2 increase, Co2 will cross the blood brain barrier and end up in CSF as carbonic acid
-the hydrogen ion will be the one that stimulates the medulla to hyperventilate to get rid of the CO2
-hydrogen will revert back to co2 form to get out
Medulla PCO2) apnea (2)
Might be related to co2 levels
pO2 peripheral ) aortic and carotid bodies sensitivyt
It will senses a drop in o2 in blood
pO2 peripheral ) hypoxic drive
- Body uses O2 receptors insert of CO2 to regulate repository cycle
- *insensitive to CO2
pO2 peripheral ) arterial pH
- Can cause a change in respiratory rate
- *independent of pH changes one sees when Co2 crosses blood brain barrier though
pO2 peripheral ) which is more sensitive
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