Week 2 - Ventillation Of Lungs Flashcards
Describe how air is drawn into the lungs?
Inspiratory muscles contract, thoracic cavity expands, pleural pressure becomes more negative, thanspulmonary pressure increases, lungs inflate, alveolar pressure becomes subatmospheric, air flows into lungs until alveolar pressure equals atmospheric pressure
Describe the equilibrium of forces in the chest?
Lungs pull in and up, thoracic cage pulls out, passive stretch of diaphragm pulls down
Describe the main features of inhalation?
At resting expiratory level is an active process, mainly by contraction of diaphragm and external intercostal muscles
Describe the main features of expiration?
At resting expiratory level its passive
How does air get into the lungs?
Moves from high pressure to low pressure so air pressure inside lungs must be lower than atmospheric pressure
Describe the volumes and pressure during inspiration and expiration?
Inspiration - increased volume of thoracic cavity, decrease in intrathoracic cavity, air drawn in
Expiration - decrease in volume of thoracic cavity, increases intrathoracic pressure, air moves out of lungs
What is forced expiration and how is it achieved?
Breathing out beyond resting expiratory level, requires force exerted by abdominal muscles and internal intercostal muscles, inspiration to resting respiratory level is passive, springs back to normal
When might forced expiration occur?
During exercise, respiratory obstruction, disease states
What might cause difficulty breathing due o decreased ability to move the abdomen?
Pregnancy, obesity, corsets
Where is pleural fluid found and what does it do?
Thin layer of fluid between visceral and parietal pleura, ensures lungs fill throracic cavity and change volume as thorax does
What will happen if the integrity of the pleural seal is broken?
The lungs will collapse
