Lecture 1 - Ventilation and respiration Flashcards
What is external respiration?
all processes involved in exchanging O2 and CO2 with the environment
Pulmonary ventilation
gas diffusion
storage and transport of O2 and CO2 exchange of gases
What is internal respiration?
Uptake of O2 and production of CO2 within individual cells
What is pulmonary ventilation?
Physical movement of air in and out of the respiratory tract
What is alveolar ventilation?
Physical movement of air in and out of the alveoli
Will be slightly lower that pulmonary as some air fills the trachea
What is Boyle’s law?
Defines the relationship between gas pressure and volume
They are inversely proportional
P= 1/V
Define pressure difference
Air flows from area of higher pressure to lower pressure
Outline inspiration
Controlled by the respiratory control centre in the medulla
Diaphragm and external intercostals contract
Diaphragm moves down and rotates the ribs towards the horizontal plane
1cm - quiet breathing
10 cm - forced inhalation
Ribs move up and out to increase thoracic cavity volume and decrease pressure so air moves in
Outline expiration
In normal breathing it is passive
Due to elastic fibres in connective tissue and surface tension of surfactant - thin film of liquid in alveoli - molecules want to move back to each other due to strong attractive forces
Elastic recoil
What muscles are involved in inspiration
Sternocleidomastoid
Scalenes
External and internal intercostals
Diaphragm
Muscle used in expiration
Internal intercostals
External abdominal oblique
Internal abdominal oblique
Transversus abdominis
Rectus abdominus
What is quiet breathing?
Eupnea
Active inhalation and passive exhalation
Diaphragmatic breathing (deep) is dominated by the diaphragm
Costal breathing (shallow) - ribcage movement
What is forced breathing
Hyperpnea
Active inhalation and exhalation
Assisted by accessory muscles
Max levels occur in exhaustion
What are the 2 respiratory formulas?
Ve = f x Vt
Volume of air moved each min = breaths per min x tidal volume
Va = f x (Vt - Vd)
Alveolar ventilation = Breaths per minute x (Tidal volume - dead anatomical space)
What is the tidal volume?
The volume of gas inspired or expired during an unforced respiratory cycle
What is inspiratory reserve volume?
Volume of gas that can be inspired at the end of a tidal inspiration
What is inspiratory capacity?
Max amount of gas that can be inspired
What is the expiratory reserve volume ?
Volume of gas that can be expired at the end of a tidal expiration
What is vital capacity?
Max amount of gas that can be expired after a max inspiration
What is the residual volume?
Volume of gas left in the lungs after max expiration
What is the functional residual capacity?
Amount of gas remaining in the lungs after a normal quiet tidal expirationW
What is the total lung capacity?
Total amount of gas in the lungs and the end of a max inspiration
What is the forced expiratory ratio?
FEV1/ FVC
Forced expiratory volume in 1 sec / forced vital capacity
What is the composition of air?
760 mmHg at sea level
N2 - 78.6%
O2 - 20.9%
H20 - 0.5%
CO2 - 0.04%
