Physio lec 2 respiratory mechanics

Question 1

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Intra-alveolar pressure/intrapulmonary pressure:

Answer 1

pressure in the alveoli

Question 2

Intrapleural presure/intrathoracic pressure:

Answer 2

pressure within pleural sac

Question 2

Rate of airflow:

affected by autonomus nervous system

Answer 2

airflow is inversly proportional to air resistance
-sympahtetic system causes bronchodialation= dec resistance or more airflow
-parasympathetic system causes bronchoconstriction= inc resistrance or less airflow

Question 2

transmural pressure gradient:

Answer 2

difference between intra-alveolar and intrapleural pressure (4mm Hg)

Question 3

opposite of inhale

Sequence of events during expiration:

3 sec

Answer 3

-inspiratory muscles relax
-Decrease in pulmonary volume
-increase in pressure (+1mm Hg)
-process continues until intrapulmonary pressure = 0

Question 4

2 sec

sequence of events in inspiration:

-contraction
-increase
-gas in

Answer 4

-contraction of inspiratory muscles
-increase in pulmonary volume and decrease in pulmonary pressure
(-1mmHg)
-atmospheric pressure higher (0) so gas moves in

Question 4

Force that stretches the lungs:

Answer 4

Transmural pressure gradient

Question 5

lung compliance

Answer 5

measure of lung expansability and distensibility

Question 6

Low compliance:

(low expansability and distensibility)

Answer 6

-lung become stiffer and less elastic
-higher elastic recoil
-less air inhaled
-fibrosis (stiffness)
-gas exchange impaired

Question 7

High compliance:

(high expansibility and distensibnility)

Answer 7

-lower elastic recoil
-easily distended
-reduces passive ability of lungs to deflate during expiriation

simply put, lungs appear manfookh

Question 8

Compliance affected by:

Answer 8

-elastin and collagen fibres
-chest wall flexibility (fat or fit)
-surface tension

Question 8

forces keeping alveoli open:

Answer 8

-transmural pressure
-pulmonary surfactant (opposes surface tension)

Question 9

Inspiratory reserve volume (IRV):

Answer 9

extra volume of air that can be inspired OVER the tidal volume= 3000ml

Question 10

Tidal volume

Aka normal breathing volume

Answer 10

volume of air entering or leaving the lungs duirng a single breath (500ml)

Question 10

Forces collapsing alveoli:

Answer 10

-elasticity from elastin
-alveolar surface tension

Question 11

Inspiratory capacity (IC):

Answer 11

(TV+IRV)
500ml+3000ml=3500ml

Question 12

expiratory reserve volume (ERV):

Answer 12

Extra amount of volume that can be actively expired (1000ml)

Question 13

Residual volume (RV):

Answer 13

minimum vol of air remaining even after maximum expiration (1200ml)

Question 14

Vital capacity (VC):

max expiration

Answer 14

max vol of air that can be moved out during maximum expiriation

(VC=IRV+ERV+TV)——- 4500ml

Question 15

Functional residual capacity (FCR):

Answer 15

Vol of air in lungs after normal expiration

FCR=ERV+RV

1200+1000=2200ml

Question 16

normal % for FEV1/FVC*100:

Answer 16

80%

(FEV1< 80%)

Question 16

total lung capacity (TLC):

Answer 16

max vol of air lungs can hold

VC+RV

Question 17

Forced vital capacity in Un/healthy individual:

forced exhale test

Answer 17

Actual FVC> predicted FVC = healthy
Actual FVC< predicted FVC= pulmonary disease

Question 18

If FVC < predicted

Answer 18

CONSTRICTIVE pulmonary disease

alveolar SA decreases

Scare tissue from pneumonia and tuberculosis

Question 19

Dead space:

Answer 19

Exists anatomically in: trachea, bronchial tree… 150 ml of air that doesnt particiapate in gas exchange

Alveolar dead space: space in alveoli where 150 ml of air doesnt participate in gas exchange—- less efficient gas exchange

Question 19

FEV1<80%

Answer 19

Obstructive pulmonary disease
-emphysema, asthma,asthma, bronchitis, decreased left heart output,pulm edema

Question 20

Pulmonary rate=

how many breaths?

Answer 20

TV* respiratory rate per min

12-18 breaths

12*500 = 6000ml

Question 21

Alveolar ventilation:

Answer 21

(TV-dead space volume)*respiratory rate

(500-150)*12= 4200ml