Physiology Flashcards
Define and provide litres: Total lung capacity
Sum of all lung volumes.
7.5 litres
Vital capacity
Sum of Inspiratory reserve volume, expiratory reserve volume and tidal volume
Around 6 litres
Functional residual capacity
Expiratory reserve volume and residual volume
Around 2.5 litres
Inspiratory reserve volume
The volume of air you can forcibly inhale after a normal inhalation
Expiratory reserve volume
The volume of air you can forcibly exhale following a normal exhalation
Residual Volume
The amount of air left in your lungs after a forceful exhalation.
Around 1.5 litres
Tidal volume
The volume of air inspired during a single ventilatory cycle
500mL
Volume is dependent on?
Volume is dependant on temperature (T), barometric pressure (P), and water vapour pressure (PH20)
Minute volume
The magnitude of pulmonary ventilation expressed in
L min-1
Bulk flow
Time derivitive of volume; e.g. mL/min or L/min
Flow velocity
units of m s-1
Anatomic dead space
Made up of all of the conducting airways where no gas exchange occurs. From the trachea to the terminal bronchiole. Volume of 150mL
Alveolar ventilation
The minute volume minus the minute volume of dead space. e.g. minute volume 7500 mL/min (500mL x 15 breaths in a minute)- dead space minute volume (2250 mL)= 5250ml/min
Muscles of inspiration
Diaphragm- contracts and moves downwards increasing the volume of the thorax. Innervated by phrenic nerve from cervival levels 3,4,5
The external intercostal muscles- cause an increase in the lateral and anteroposterior dimensions of the thorax
Accessory muscles- scalene, sternomastoids
Expiration
Passive during quiet breathing due to the elasticity of the chest wall and lungs.
In exercise the abdominal wall muscles and the internal intercostals assist with active expiration.
