Lecture 20: Respiratory Mechanics Flashcards

1
Q

what are alveoli

A

single layer of cells surrounded by capillaries across which oxygen and CO2 exchange occurs

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2
Q

What are type I alveoli cells

A

epithelial cells forming exchange surface w/ the capillaries

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3
Q

what are type II alveolar cells

A

-scattered among type I
-make surfactant that coats alveoli to reduce surface tension

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4
Q

what do alveolar pores do

A

connect adjacent alveoli and equalize air pressure

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5
Q

what do alveolar macrophages (dust cells) do

A

they are phagocytic cells that consume microbes and dust particles

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6
Q

what helps prevent mammalian lungs from collapsing

A

surfactant - the fluid lining the inner surface of the alveoli, reduces surface tension so that less pressure is needed to inflate the lungs

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7
Q

why is the pleural space between the visceral and parietal pleura important

A

it reduced friction, allowing the pleurae to slide against eachother
- also acts to glue the lung to the chest wall

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8
Q

how does the pressure inside the pleural cavity help keep lungs expanded

A

pressure inside pleural cavity is negative in respect to the atmospheric pressure which keeps the lung slightly expanded

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9
Q

If P alveoli is < P atmosphere, then air (enters/exists) lung

A

enters

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10
Q

If P alveoli is > P atmosphere, then air (enters/exists) lung

A

exits

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11
Q

the active process of inhalation in mammals occurs when

A

motor neurons in the phrenic nerve stimulate the diaphragm to contract
- increases size of thoracic cavity
- the pressure in pleural cavity becomes more (-), and Palv > Ppleural cavity so the alveoli expand
- adhesion of pleural membranes assists in expansion of lungs

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12
Q

air moves into the alveoli unit until..

A

the air pressure in alveoli equals atmospheric pressure

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13
Q

when Palv=Patm…

A

there is no movement of air b/c there is no pressure gradient to act as a driving force

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14
Q

what causes exhalation to occur

A

the phrenic nerve stops firing –> inspiratory muscles relax

-elasticity of thorax and lung decrease the size of alveoli, increasing Palv

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15
Q

what is residual volume (RV)

A

the air left in lungs after a forced exhalation

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16
Q

what is inspiratory capacity (IC)?

A

volume of air that can be inhaled in addition to normal exhalation

17
Q

what is functional residual capacity (FRC)

A

total volume of air in lungs after a maximal inspiratory

18
Q

what is inspiratory reserve volume (IRV)

A

amount of air that can be further inhaled after a normal inhalation