Lecture 14 Flashcards
What are the series of steps in respiration, what category do they fit into? How much oxygen is breathed in and carbon dioxide emitted roughly?
- Ventilation: moving air into and out of the lungs (supplying oxygen to and removing carbon dioxide from the alveoli, bulk flow).
- Gas exchange: exchange of oxygen and carbon dioxide across the alveolar membrane (oxygen into blood and carbon dioxide into lungs, diffusion).
- Gas transport: delivering the oxygen from lungs to tissues and transport the carbon dioxide produced by metabolism to the lungs (done by cardiorespiratory system, bulk flow).
- Gas exchange: exchange of oxygen and carbon dioxide between the capillaries and the cells.
- Cellular respiration: cells use the oxygen and produce carbon dioxide
roughly 250 ml/min of oxygen breathed in, roughly 200 ml/min of carbon dioxide breathed out at rest.
What are the functions of the respiratory system?
Provide oxygen, eliminate carbon dioxide, (filters, warms and humidifies the air we breathe), communication, sense of smell, regulates the pH of the blood, in association with the kidneys, defends against microbes, production of chemical mediators, trapping and dissolving blood clots and temperature regulation.
What is Dalton’s law? What happens to air proportions if pressure changes?
Partial pressure = the fraction of individual gas x total gas pressure. The proportions of air parts remains roughly the same with different pressures.
How do we move air into the lungs?
By generating a pressure gradient (difference between the lungs and the environment).
What occurs during inspiration and expiration?
Inspiration: diaphragm and external intercostal muscles constract, leading to an increase in thoracic volume, the lungs expand also, increasing volume (decreasing pressure and hence air moves into the lungs).
Expiration: process of moving air out of the lungs, the inspiratory muscles relax, the diaphragm moves upwards, this leads to decrease in thoracic and lung volume, increasing alveolar pressure and moves air out of the lungs. This is a mostly passive process as it is driven largely by elastic recoil, but can also use accessory muscles to assist.
What is the intrapleural space? How does it link the thoracic wall and lungs?
The intrapleural space is the small space between the visceral and parietal pleura. It has lower pressure than the area around it (because the lungs have a tendency to pull inwards and the thoracic wall has a tendency to pull outwards.)and hence pulls the lungs towards itself via the pressure difference, if the thoracic wall expands this space will decrease in pressure, causing the lungs to expand more and thereby linking the thoracic wall and lungs.
What also limits how much the pressure change of the intrapleural space allows the lungs to expand?
The cohesion of the visceral and parietal pleura and the compliance of the thorax and lungs.
