Breathing and respiratory pressures

Question 1

Inspiration

Answer 1

Diaphragm and external intercostal muscles contract

• increases intrapulmonary volume
• decreases gas pressure
• creates vacuum for air to flow in until pressure equals atmospheric pressure

Question 2

Exhalation

Answer 2

-largely a passive process
(Depending on elasticity)
-intrapulmonary volume decreases
-has pressure increases
-gas passively flow out to equalize pressure
-forced expiration can occur mostly by contraction of intercostal muscles to depress the rib cage

Question 3

Intra-pulmonary pressure

Intra-alveolar pressure

Answer 3

• air pressure in the alveoli
• negative in inspiration
• positive in expiration

Question 4

Respiratory pressures

Answer 4

• atmospheric
• intrapulmonary/intra-alveolar (lungs)
• intrapleural (pleural cavity and serous fluid)
• transpulmonary (between intrapulmonary and intrapleural)

Question 5

Atmospheric pressure

Answer 5

-760mmHg
-respiratory pressures are relative to atmospheric pressures
(Negative: less than atmospheric, positive: more than atmospheric)

Question 6

Intrapleural pressure

Answer 6

• always negative
• prevents lungs from collapsing
• dependent on surface tension, lung elasticity and elasticity of chest
• if intrapleural pressure = atmospheric pressure, lungs will recoil and collapse

Question 7

Atelectasis

Answer 7

-if bronchioles become plugged, alveoli absorb all their air and collapse (from a lack of surfactant)

Question 8

Pneumothorax

Answer 8

-lung collapse from air in pleural cavity

Question 9

Asthma

Answer 9

• active expiration from a smaller passageway
• internal intercostale contract to depress rib cage
• abdominal muscles contract squeezing organs against the diaphragm