46R. Respiratory - Overview of respiration and respiratory mechanics Flashcards
what are the 4 steps in respiration
- ventilation
- Gas exchange between alveoli and blood
- Gas transport in the blood
- Gas exchange at the tissue level
what is ventilation
the mechanical process of moving gas in and out of the lungs
what is the gas exchange between alveoli and blood briefly
the exchange of O2 and CO2 between the air in the alveoli and the blood in the pulmonary capillaries
describe the gas transport in the blood briefly
the binding and transport of O2 and CO2 in the circulating blood
what is the gas exchange at the tissue level briefly
the exchange of O2 and CO2 between the blood in the systemic capillaries and the body cells
quiet inspiration and expiration is collectively known as what
tidal volume
the process of quiet breathing is under automatic control from what?
respiratory control centre
what are the lung mechanics in quiet respiration
Air is drawn into the airways by ACTIVE expansion of the thoracic cavity, which in turn expands the lungs
what is BOYLE’s Law
inverse relationship between pressure and volume of a gas
describe the changes in pressure during quiet inspiration
- contraction of inspiratory muscles
- chest wall and lungs stretch
- increased size of lungs makes intra-alveolar pressure fall
- then air enters the lungs down the pressure gradient until the intra-alveoli pressure becomes equal to atmospheric pressure
is inspiration passive or active
active
The increase in the size of the lungs make the intra-alveolar pressure to fall. WHY?
because air molecules become contained in a larger volume
what are the main muscles in inspiration
diaphragm and external intercostal
what are the two mechanics of ventilation with normal quiet inspiration
pump handle movement
bucket handle movement
pump handle movement
bucket handle movement
which is anterior and superior movement and which is lateral and superior
pump handle movement- anterior
bucket handle movement- lateral
what are the lung mechanics in quiet expiration
- air expelled from airways passively by relaxing muscles of inspiration
- reduces volume of thoracic cavity
- reduces volume of lunges
is expiration at rest passive or active
passive
describe the changes in pressure during quiet respiration
relaxation of inspiratory muscles
recoil of chest wall and lungs - elastic properties, return to pre inspiratory size
- as the lungs recoil, the space inside them gets smaller so intra-alveolar pressure rises
- air then moves from the high pressure out into the low pressure environment (outside the lungs)
- air continues to leave until lung pressure and atmospheric pressure are equal
what is the resting expiratory level
the point before you inspire, having just inspired
lungs- pull inward
chest wall - pulls outward
diaphragm - pulls downward
body wants to go back to this resting state
is inspiration active or passive
active
describe inspiration
muscles contract to allow the chest wall to overcome the inward pull of the lung recoil.
This helps the chest wall (increasing space) push out against the inward pull of the lungs.
is expiration active or passive
passive
describe expiration to me simply
muscles stop contracting
return to resting expiratory level
diaphragm moves back into resting position
inward pull of lung recoil
air leaves lungs as they are at higher pressure than outside
what creates surface tension on alveoli
they are lined with fluid
what lung structure is lined with fluid to create surface tension and does this improve expansion or limit expansion
Alveoli
it limits expansion
why does the fluid lining the alveoli causing surface tension limit their expansion
decreases compliance making it difficult for alveoli (and therefore lungs) to expand
what is secreted by type II pneumocytes
surfactant
what secretes surfactant
type II pneumocytes
what does surfactant do
has detergent like properties
- stabilizes inflation of alveoli
- prevents collapse
By reducing surface tension, surfactant helps keep the alveoli open, preventing them from collapsing - reduces surface tension
- prevents atelectasis (in combination alveolar interdependence)
As the alveoli inflate during inspiration, surface tension increases, and as they deflate during expiration, surface tension decreases
what is atelectasis
lung collapse
how does surfactant prevent atelectasis
By stabilizing the alveoli and reducing surface tension, surfactant helps prevent atelectasis
who might have underdeveloped surfactant release
newborns before 25 weeks
the lungs naturally want to pull in. Why?
elastic properties
are the lungs physically attached to the cell wall
no
what is pleural fluid
a thin layer of fluid found in the space between the visceral pleura (covering the lungs) and the parietal pleura (lining the chest wall)
what is the pleural seal
the pleural fluid creates a seal between the lung and the thoracic wall so this is what keeps the lungs against the chest wall
The inward pull of the lung results in a ………. pressure between the pleura
negative
explain why the inward pull of the lung results in a negative pressure between the pleura
Pressure in the pleura space (between visceral and parietal pleura) is negative (relative to atmospheric) due to: elastic recoil of lung pulling visceral pleura inward and chest wall pulling parietal pleura outward
Sticking Together: This suction keeps the (lungs) stuck to the inside of the (chest wall).
what stage is the intrapleural pressure negative
never. it is negative through expiration and inspiration
what is intrapleural pressure
the pressure in the space between the lungs and the chest wall (pleural space)
what is called when air gets into the pleural cavity
Pneumothorax
what causes a pneumothorax
chest injury
lung disease
medical procedure
