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Phys2 Resp Intro
Question | Answer |
---|---|
Two main components of air? | Nitrogen: 79% Oxygen:21% |
What is the difference b/w internal and external respiration? | Internal: occurs in the mitochondria, converting O2 to CO2. External: occurs in the lungs, O2 and CO2 exchange. **External is necessary for internal to occur. |
What all does external respiration include? | 1.lungs. 2.Circulatory system (pulmonary and systemic circulations) **everything involved in getting O2 to the tissue and removing CO2. |
External respiration: Ventilation | the process by which gas is brought in and out of the lungs |
External respiration: Diffusion | the process by which gas moves between the circulation and the lung & the circulation and the cells. **Gas diffusion moves down PARTIAL PRESSURE gradients |
External respiration: Perfusion | the process by which gases in the blood are transported around the body from lungs to cells and vice versa |
What drives all the processes of external respiration? | BULK FLOW |
When does diffusion of gas down its partial pressure gradient stop? | when EQUILIBRATION has occured **Remember partial pressure are the driving force, so when they equal, no net movement will occur. |
PO2 atmospheric? PO2 upper respiratory tract? PO2 alveoli? PO2 venous circulation? PO2 interstitial? | atmospheric: 159mmHg (21% of 760mmHg). Upper resp tract: 149mmHg (due to the addition of water). Alveoli: 100mmHg (becomes 96mmHg in arterial BL). Venous: 40mmHg. Interstitial: 20mmHg |
What are the 2 O2 partial pressure gradients at the: 1.BL-gas interface? 2.BL-cell interface? | 1.gas:100 - BL:40mmHg 2.BL:96 - Cell:20mmHg |
is the CO2 PP gradients larger than O2 PP gradients? | NO! 1.BL-gas interface:46-40mmHg **Arterial BL has a PCO2 of 40mmHg **Venous BL has a PCO2 of 46mmHg |
How can CO2 still diffuse across such a small gradient (6mmHg)? | CO2 has a faster diffusion rate b/c it is much more soluble than O2. |
How does perfusion and ventilation maintain diffusion? | by creating a bulk flow system. They keep the PO2 high in the BL so that there is a continuously HIGH driving force (large partial pressure difference) at the BL-Cell interface. |
Dalton's law for partial pressure? | Px = Total Pressure X Fractional conc of X. **Therefore Px=Ptotal X Fx |
Dalton's law equation for PO2 upper respiratory tract? | PIO2 = (Patmospheric - Pwater) X FIO2. **Must add in partial pressure of water vapor that is present inside the body: PIO2 = (760-47) X 0.21. **149mmHg** |
What is the partial pressure of water vapor in the upper respiratory tract? | 47mmHg. Must be subtracted from total atmospheric pressure before the 21% concentration of O2 can be multiplied. |
How does partial pressure of a gas relate to partial pressure of a solution? | The gas will dissolve into the solution until the rate of dissolving equals the rate of that molecule leaving (equilibrium) **it will become the PP that the gas is. |
How do alveoli make diffusion more efficient? | since greater, thinner surface area increases diffusion, alveoli make the diffusion SA 500X greater |
Describe the tissue layers O2 travels to leave the alveoli and enter the BL | 1.surfactant. 2.Alveolar epithelium. 3.interstitium (BM). 4.Capillary endothelium. |
What also increases SA in the lungs besides Alveoli? | BRANCHING!! The airways branches 23 times from the trachea. 1.Conduction Zone: Branches 1-16. 2.Respiratory Zone: Branches 17-23 (SA increases dramatically once the terminal bronchioles start). |