Physiology Spring L3 / L4 Mechanics Of Breathing

Front 1

How does diaphragm contraction affect intrathoracic volume and pressure?

Back 1

this will increase the volume, and lower the pressure (PV=nRT)

Front 2

How do external intercostals affect thoracic cavity shape?

Back 2

this will increase the side to side dimensions

Front 3

What are the primary muscles of expiration? what do they do?

Back 3

the abdominal muscles

these compress the abdominal cavity, and push up the diaphragm

Front 4

how does expiration occur during quiet breathing?

Back 4

this occurs simply by passive recoil of the lung tissue

Front 5

what moves air in and out of the lungs? (very generally)

Back 5

a pressure gradient, 1 torr

Front 6

how does the intrapleural pressure compare to the intralveolar pressure?

Back 6

this should always be lower! this will keep the alveoli open

Front 7

what is the transmural pressure?

Back 7

this is the pressure gradient that keeps the lung stretched open.

transmural P= alv P- intrapleural P

Front 8

what characteristics of the lung favor collapse?

Back 8

this would be the elastin and collagen

Front 9

what is compliance?

Back 9

change in volume over change in pressure

Front 10

how does the level of elastic tissue in the lungs affect compliance?

Back 10

this has an inverse relationship

the more elastic tissue, the lower the compliance

Front 11

what is hysteresis? what causes it?

Back 11

this is the difference in the PV loops for inspiration and expiration in regards to compliance.

these are different, due to surface tension in the alveoli

Front 12

how do inspiration and expiration volumes relate, at a given pressure?

Back 12

at a given pressure, expiration will always be the greater volume

Front 13

what happens during a pneumothorax?

Back 13

the lungs collapse, and the chest expands. this is due to the loss of the vaccum between the two (transmural pressure)

due to AIR being introduced into the plural space

Front 14

How does compliance change in emphysema? why?

Back 14

the compliance is increased, due to a loss of elastic tissues. so at a given volume, the recoil force is much lower

STEEP SLOPE

Front 15

how does compliance change during fibrosis?

Back 15

this is a stiffening of the tissues, this results in lower compliance. and more force at a given pressure. LOW SLOPE

Front 16

What is the law of laplace? what does it relate to?

Back 16

this relates to alveoli and their collapsing pressure

P=2T/r, with Pressure, surface Tension, and radius

Front 17

how does surfactant affect surface tension?

Back 17

this lowers surface tension, thus lowering the collapsing pressure

Front 18

what is atelectasis?

Back 18

this is the collapse of SMALL alveoli, due to the law of laplace, and the lack of surfactant to lower surface tension

Front 19

when does surfactant production begin?

Back 19

week 24

Front 20

when is surfactant always present by?

Back 20

week 35

Front 21

How does the resistance relate to the radius?

Back 21

the resistance is INVERSELY proportional to the radius to the 4TH power!

Front 22

what is the law that indicates the resistance related to the radius?

Back 22

Poiseuill's law

R=8*viscosity*lenght/ (pi* R^4)

Front 23

how does the PNS affect airway resistance?

Back 23

this INCREASES resistance

Front 24

how does the SNS affect airway resistance?

Back 24

this DECREASES resistance

Front 25

How does asthma affect airway resistance? what mechanisms?

Back 25

this increases airway resistance, due to: thickening of walls due to inflammation, plugging of airway with mucus, and constricting spasms

Front 26

What methods can treat asthma?

Back 26

B adrenergic agonists

cortiocsteroids

antileukotrienes

Front 27

what causes emphaysema?

Back 27

this is caused by macrophages releasing lots of tyrpsin