pulmonary ventilation

Question 1

air moves in and out lungs cos of what

Answer 1

pressure diff
high to low

Question 2

explain boyles law

Answer 2

Gas law

States that the pressure
of a gas is inversely proportional to its volume

P1V1=P2V2

Question 3

explain muscle respiration in terms of when breathing in

Answer 3

Inspiration
breathing in, inhalation

Diaphragm
constriction causes dome to flatten

Muscles that elevate ribs & sternum e.g.,
- External intercostals
- Pectoralis minor
- Scalenes (neck)

increase size of thoracic cavity

Question 4

explain muscle respiration in terms of breathing out

Answer 4

Active Expiration
breathing out, expiration

Muscles that depress ribs & sternum e.g.,
- Internal intercostals
- Abdominal muscles
decrease size of thoracic cavity

Passive Expiration
elastic lung recoil:
- Elastic fibres in alveolar wall
- Surface tension of fluid film lining alveoli

Question 5

name the muscles of inhalation

Answer 5

sternocleidomastoid

scalenes

external intercostals

diaphragm

Question 6

name the muscles of exhalation

Answer 6

internal intercostals

external oblique

internal oblique

transversus abdominis

rectus abdominis

Question 7

explain the changes of thoracic cavity during inhalation and exhalation

Answer 7

on inhalation the sternum moves outwards

on inhalation the diaphragm contacts and moves downwards

Question 8

air movement results from diff between what

Answer 8

atmospheric pressure (760mmHg)
and
Alveolar pressure
Palv (inside alveolus)
- Decrease = air moves into lungs

Question 9

summarise the cycle of air movement

Answer 9

at rest (diaphragm relaxed):
- alveolar pressure = 760mm Hg

during inhalation (diaphragm contracting):
- alveolar pressure = 758mm Hg less than the atmospheric = so air moves in

during exhalation (diaphragm relaxing):
- alveolar pressure = 762 mm Hg, more than atmosphereic = so air moves out

atmospheric pressure is remained at 760mm Hg throughout cycle

Question 10

what is pleural cavity

Answer 10

space between lung & chest wall

Question 11

what is found inside pleural cavity

Answer 11

Pip (written as = big P, tiny ip)

Question 12

what happens if If Pip < Palv

Answer 12

alveoli expand (= normal)

Question 13

what is Pneumothorax

Answer 13

If air enters pleural cavity, Pip= atmospheric pressure

alveoli cannot expand

lungs collapse

Question 14

what can be seen in an Pneumothorax CT scan

Answer 14

Lung collapsed

Dark, air-filled space

Question 15

name 3 other factors that affect rate of pulmonary airflow

Answer 15

Surface tension of alveolar fluid

Lung compliance

Airway resistance

Question 16

explain the 3 factors that can affect rate of pulmonary airflow

Answer 16

Surface tension of alveolar fluid:
- Overcome by surfactant
lipoprotein molecules in alveolar fluid prevent alveoli collapsing & allowing lungs to expand
- Less surfactant in premature infants causes
‘respiratory distress syndrome’

Lung compliance
- Capacity for stretching

Airway resistance
- Controlled by pressures and airflow

Question 17

what causes interpleural pressure

Answer 17

pleural cavity

with can lead to pneumothorax

Question 18

what is the Role of Surfactant in Lung

Answer 18

Decreases surface tension of alveoli to prevent them from collapsing.

Question 19

describe the diff between immature vs mature lung

Answer 19

Immature lung:
Not conducive to gas exchange

Mature lung:
Larger surface area

Question 20

what does lung compliance mean

Answer 20

Effort required to stretch lungs & thoracic wall

Question 21

explain high compliance

Answer 21

high compliance = easy expansion

e.g., thin balloon has high compliance as easy to inflate

Question 22

how is there effort required to stretch the lungs and thoracic wall

Answer 22

Elastic forces of the lung:

presence of elastic & collagen fibres

surface tension.

Question 23

explain airway resistance

Answer 23

Resistance of the respiratory tract to airflow
- during inhalation and exhalation

Decreases as diameter of airways increases
- walls pulled outwards, smooth muscle relaxation

Question 24

explain air volume as we breathe

Answer 24

Only small proportion of air in lungs exchanged during single, quiet respiratory cycle
- inhale + exhale

Increase by inhaling more vigorously & exhaling more completely

Maximum effort of inspiration
- Volume of air in lungs = Total lung capacity

Question 25

name the 4 pulmonary volumes

Answer 25

tidal volume
Inspiratory reserve volume
Expiratory reserve volume
Residual volume

Question 26

explain the pulmonary volumes tidal volume

Answer 26

amount of air moved into or out of lungs during a normal inspiration or exhalation (~500ml)

Question 27

explain the pulmonary volume Inspiratory reserve volume

Answer 27

amount of air that can be inspired forcefully after inspiration of normal tidal volume (~3100ml)

Question 28

explain the pulmonary volume Expiratory reserve volume

Answer 28

amount expired forcefully after normal expiration (~1200ml)

Question 29

explain the pulmonary volume Residual volume

Answer 29

still remaining in respiratory passages & lungs after most forceful expiration (~1200ml)

Question 30

what are pulmonary capacities

Answer 30

Sum of two or more pulmonary volumes

Question 31

name the 4 pulmonary capacities

Answer 31

Inspiratory capacity
functional residual capacity
vital capacity
total lung capacity

Question 32

explain the pulmonary capacity: Inspiratory capacity

Answer 32

tidal vol + inspiratory reserve vol

amount can inspire maximally after normal expiration (~3600 ml)

Question 33

explain the pulmonary capacity: Functional residual capacity

Answer 33

expiratory reserve vol + residual vol

amount remaining in lungs after normal expiration
(~2400 ml)

Question 34

explain the pulmonary capacity: Vital capacity

Answer 34

inspiratory reserve vol + tidal vol + expiratory reserve vol

max can expel after max inspiration (~4800 ml)

Question 35

explain the pulmonary capacity: Total lung capacity

Answer 35

inspiratory reserve vol + expiratory reserve vol + tidal vol + residual vol (~6000ml)

Question 36

explain how we measure these volumes and capacities

Answer 36

Spirometry:
process of measuring volumes of air that move in & out of respiratory system

Spirometer:
device used to measure these pulmonary volumes
- Values obtained useful in diagnosing problems with pulmonary ventilation, e.g., asthma.