L13 - respiratory physiology - volumes and pressures

Question 1

define tidal volume (Vt)

Answer 1

total vol of air breathed in and out in one breath at rest

Question 2

define inspiratory reserve volume (IRV)

Answer 2

the max amount the lung vol can be increased by above Vt (forceful inhale)

Question 3

define expiratory reserve volume (ERV)

Answer 3

further vol that can be exhaled forcefully after Vt

Question 4

what is residual volume (RV)

Answer 4

volume left in lungs after max expiratory effort (cant be measured)

Question 5

what is inspiratory capacity

Answer 5

vol of air that can be inhaled in one forceful inhale (Vt + IRV)

Question 6

what is expiratory capacity

Answer 6

vol of air that can be exhaled in one forceful exhale (Vt + ERV)

Question 7

what is vital capacity

Answer 7

max volume of air breathed in and out in one forceful breath (ERV + Vt + IRV)

Question 8

what lung capacities can a spirometer measure

Answer 8

any not involving RV

Question 9

what is total lung capacity

Answer 9

RV + ERV + Vt + IRV

Question 10

define alveolar ventilation

Answer 10

vol of fresh air entering alveoli every min

Va

Question 11

define alveolar minute ventilation

Answer 11

total ventilation per minute (Ve)

Question 12

what is the equation for alveolar minute ventilation

Answer 12

Ve = R x Vt

R= breathing rate - breaths per min 
Vt = tidal vol

Question 13

why are Va and Ve different

Answer 13

because gas exchange doesn’t occur in conducting zone so isn’t fresh air

Question 14

what is anatomical dead space?

Answer 14

air in the pharynx to terminal bronchioles (conducting zone)

Question 15

what is the value for anatomical dead space

Answer 15

~150ml (fixed)

Question 16

what is the equation for Va

Answer 16

Va = Ve - Vd

Vd = breathing rate x 150 (dead space vol)

Question 17

what is Vd

Answer 17

dead space ventilation (breaths per min x dead space vol)

Question 18

explain physiological dead space

Answer 18

in healthy lungs physiological ds = anatomical ds

if some alveoli have poor blood supply there will be no gas exchange there (alveolar dead space)

Question 19

equation for physiological Dead space

Answer 19

physiological ds = 150 + alveolar dead space

Question 20

what is the equation that shows how lung ventilation occurs

Answer 20

flow = change in pressure (Palv - Patm)
___________
resistance

Question 21

what is boyles law

Answer 21

if vol increases = pressure decreases

if vol decreases = pressure increaes

Question 22

what is intrapleural pressure (Pip)

Answer 22

pressure between the pleural membranes

Question 23

what is balanced at FRC?

Answer 23

inward recoil of lungs and outward recoil of chest wall

Question 24

what happens to the pleural membranes at FRC?

Answer 24

inward recoil of lungs and outward recoil of chest wall pull the membranes apart slightly creating a small pressure for Pip

Question 25

what is Palv at FRC?

Answer 25

0

Question 26

function of Ptp

Answer 26

the force that makes alveoli expand in response to chest wall expansion

Question 27

describe sequence of events (and pressure changes ) during inspiration

Answer 27

1. chest wall expands
2. Pip falls (more -ve)
3. causes Ptp to increase causing alveoli to expand
4. Palv decreases due to increased volume
5. Palv

Question 28

describe sequence of events (and pressure changes ) during expiration

Answer 28

1. chest wall recoils inward
2. Pip increases (less -ve)
3. causes Ptp to decrease
4. expanded lungs recoil compressing alveoli
5. Palv > Patm so air forced out

Question 29

what causes Pip to increase

Answer 29

expiration

Question 30

what happens to Ptp when Pip

increases

decreases

Answer 30

Ptp does the opposite

decreases

increases

Question 31

what causes alveoli to expand

Answer 31

increase in Ptp

Question 32

what causes Pip to decrease

Answer 32

inspiration