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MCRT Sciences
MCRT Physics sec. 4 & 5
| Question | Answer |
|---|---|
| Describe Hooke's law | an elastic body will stretch equally for each unit of force (weight) applied, up to the elastic limit, beyond which causes permanent distortion. |
| Define compliance | the ease in which the lungs distend. |
| The reciprocal of compliance is: | elastance |
| Formula used to calculate lung compliance: | change in vol / change in pressure ml/cmH2O |
| normal compliance: | 100 ml/cmH2O |
| Describe a time constant | the time required to fill the lungs to 63% capacity |
| formula to calculate time constant | lung compliance x Raw |
| Describe LaPlace's law | the inflation pressure is inversely related to the radius and directly related to the surface tension at the air-liquid interface |
| define surface tension | then tension found at the surface of a liquid created by the cohesive forces inside the liquid |
| cohesive | attraction between like molecules |
| How is the premature lung affected by LaPlace's law? | The lungs have minimal surfactant production resulting in high surface tension making it hard to expand them. |
| Define hydrostatic pressure | pressure created by a column of liquid and is depends on the density and height of the liquid. |
| Define osmotic pressure | pressure created by osmosis |
| Define osmosis | movement of a solvent through a semipermeable membrane from an solution of lower concentration to a solution of higher concentration |
| List the 4 pressures that influence the movement of fluid into and out of the capillary. | capillary hydrostatic, capillary osmotic pressure, interstitial hydrostatic pressure, interstitial osmotic pressure |
| define diffusion | passive movement of molecules from an area of higher concentration to an area of lower concentration |
| describe a semipermeable membrane | a membrane that only allows solvents to pass through it |