pafl 6: respiratory 2

atmosphere pressure

pressure surrounding the body and in the nose and mouth

alveolar pressure

pressure within the individual alveolus

intrapleural pressure

pressure within the pleural cavity

transpulmonary pressure

difference between alveolar pressure and intrapleural pressure

boyles law

when the volume increases, the pressure decreases

when the volume decreases, the pressure increases

when does inspiration occur

when atmospheric pressure is greater than alveolar pressure, air moves into the lungs

when does expiration occur

when alveolar pressure is greater than atmospheric pressure, air moves out of the lungs

primary muscles of inspiration

diaphragm and external intercostals

muscles used for max inspiration

sternocleidomastoid

scalenes

pectoralis minor

serratus anterior

normal resting expiration

achieved passively by relaxing the diaphragm and external intercostal muscles

muscles used for max expiration

internal intercostals and abdominals

how does the diaphragm shape change when contracted

goes from dome shaped to flat shape

how does the diaphragm shape change when relaxed

goes from flat shaped to dome shaped

sequence of events during one respiratory cycle

1) diaphragm contracts

2) expansion in chest wall

3) Vip increases

4) Pip decreases

5) Ptp increases

6) Valv increases

7) Palv decreases

lung compliance

the ease with which lungs can be expanded

what is lung compliance determined by?

elastic connective tissue

surface tension, influenced by surfactants

what is the compliance equation?

change in volume/change in transpulmonary pressure

total lung capacity in males and females

male: 6L

female: 4.2 L

tidal volume

Amount of air that moves in and out of the lungs during a normal breath

at rest around 0.5 L

activity/exercise >0.5 L

minute ventilation

tidal volume x respiratory rate

dead space

The portion of the tidal volume that does not reach the alveoli and thus does not participate in gas exchange.

150 mL

negligible in a healthy lung

alveolar ventilation

(tidal volume - dead space) x respiratory rate

maximum voluntary ventilation

The volume of air a person can move into and out of the lungs during maximum effort lasting for 12 to 15 seconds.

useful to evaluate exercise tolerance and respiratory muscle endurance

average male: 140-180 L/min

average female: 80-120 L/min

Forced Vital Capacity (FVC)

maximum volume of air that can be forcefully exhaled after a maximum inhalation

Forced expiratory volume in 1 second (FEV1)

amount of air expelled in I second after maximal inspiration

ratio of FEV1/FVC expressed as a %

healthy individuals can expire at least 80% of the vital capacity in one second

obstructive lung disorders

REDUCED AIRFLOW

decreased volume of FVC

decreased volume of FEV1

decreased FEV1/FVC

Examples of obstructive lung disorders

asthma, emphysema, chronic bronchitis, COPD, localized airway obstruction

restrictive lung disease

RESTRICTION IN LUNG EXPANSION

decreased volume of FVC

decreased volume FEV1

normal or higher FEV1/FVC

normal levels of FEV, FVC and %

FEV: 4.0 L

FVC: 5.0 L

%: 80

obstructive levels of FEV, FVC and %

FEV: 1.3 L

FVC: 3.1 L

%: 42

restrictive levels of FEV, FVC and %

FEV: 2.8 L

FVC: 3.1 L

%: 90

maximum expiratory flow rate

max airflow where an increase in effort cannot cause a greater flow rate

at high expiratory pressures, there is a closing tendency of the small airways

maximum expiratory flow rate is volume dependent

changes of volumes and capacities in obstructive lung disease

Increase TLC

Increase RV

Decreased VC

decreased max expir flow rate

changes of volumes and capacities in restrictive lung disease

decreased TLC

decreased RV

Decreased VC

decreased max expir flow rate

examples of restrictive lung disease

pulmonary fibrosis

kyphoscoliosis

muscular dystrophy

sarcoidosis