Term
Distinguish between ventilation, gas exchange and cell respiration.
Ventilation |
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Definition
Ventilation = breathing, or the bulk movement of aire into and out of the lungs by:
- inhalation: which occurs when muscular contractions increase the volume of the lungs thus decreasing the pressure so air enters the lungs,
- exhalation, when muscular relaxation decreases the volume of the lungs thus increasing pressure so gases exit the lungs |
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Term
Distinguish between ventilation, gas exchange and cell respiration.
Gas Exchange |
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Definition
| The process whereby O2 is acquired and CO2 is removed between respiring cells and the environment; the gas exchange surface = alveoli |
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Term
Distinguish between ventilation, gas exchange and cell respiration.
Cell Respiration |
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Definition
| Breakdown of glucose and other molecules in the mitochondria of cells creating a constant demand for 02 and a need to eliminate CO2 |
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Term
| Explain: the need for a ventilation system. |
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Definition
- adequate lung ventilation is essential to gas exchange which is in turn essential to cell respiration and the energy needs of cells, tissues, organs and organisms
- ventilation provides a continual supply of fresh air to the lungs and helps to maintain a large diffusion gradient for respiratory gases across the gas exchange surface of teh alveoli
- O2 must be delivered regularly to supply the needs of respiring cells
- CO2 must be quickly eliminated from the body to reduce its toxic effects |
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Term
| Describe the features of alveoli that adapt them for gas exchange. |
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Definition
Alveoli: the millions of thin-walled, dead-ends of the bronchioles forming clusters of air sacs acting as the respiratory surface with features of:
- large surface area: surface area of the alveolar epithelium - 100m2
- thin: single cell layer of epithelium across which diffusion occurs
- moist: gasses need to dissolve before passing membranes
- rich blood supply: extensive net of capillaries for transport of gasses to and from alveoli |
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Term
Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and external intercostal muscles, the diaphragm and the abdominal muscles.
Inhalation |
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Definition
- diaphragm contracts
- external intercostal muscles contract
- increased volume of thorax/thoracic cavity
- decreasing air pressure in lungs
- air rushes in down air pressure gradient |
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Term
Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and external intercostal muscles, the diaphragm and the abdominal muscles.
Exhalation |
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Definition
- diaphragm relaxes
- external intercostal muscles relax
- decreased volume of thorax/thoracic cavity
- increasing air pressure in lungs
- air rushes out down air pressure gradient
- abdominal muscles contract during active exhalation
- elastic recoil of lungs help exhalation |
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