Ventilation in mammals: Inhalation + exhalation Flashcards
What is the process of ventilation?
Where air must move in + out of lungs on regular basis so lungs can act as gas exchange system
What are the 2 stages of ventilation?
Inhalation (inspiration) and exhalation (expiration)
What is ventilation a result of?
Pressure changes within thorax, + involves ribs, intercostal muscles, diaphragm, and pleural membrane
When explaining how ventilation works, what order should u go in?
- State what muscles are contracting or relaxing
- How this increases/decreases volume of thorax
- How volume change increases/decreases the pressure within thorax
State that air moves from low pressure in lungs to high pressure outside lungs
What type of process is inhalation and why?
Active process + requires energy
Due to contraction of several sets of muscles
Describe the process of inhalation:
- External intercostal muscles contract
- Ribcage moves up + out
- Diaphragm contracts + flattens
- Volume of thorax increases
- Pressure inside thorax decreases
- Air is drawn in
Why do the lungs increase in volume when thorax does in inhalation?
Due to pleural membrane forming an air-tight seal around lungs
What does increase in volume in lungs cause?
Pressure within lungs to decrease
Pressure inside lungs is now lower than pressure outside of lungs + air enters from this higher pressure
Describe the process of exhalation:
- External intercostal muscles relax
- Ribcage moves down + in
- Diaphragm relaxes + becomes dome-shaped
- Volume of thorax decreases
- Pressure inside thorax increases
- Air is forced out
What type of process is exhalation?
Passive process, doesn’t require energy
What does decrease of volume in lungs cause?
Pressure in lungs increases
Pressure in lungs now higher than pressure outside of lungs + air moves from higher pressure out via trachea
What is the role of elastic fibres within wall of alveoli during exhalation?
They recoil + further reduce volume of thorax
What is the process of forced exhalation?
Active process
Involves contraction of intercostal muscles to pull ribs downwards + inwards quicker, + contraction of abdominals forces diaphragm upward
What is the result of forced exhalation?
Quickly decrease volume + increase pressure within thorax
