airflow of upper respiratory tract

how does air first enter the body?

via the nasal cavity

what does the air come across as it enters the nasal cavity?

ciliated pseudostratified columnar epithelial cells

what do the nasal cavity epithelial cells help do?

- moisten the air

- remove large particles of dust

- raise the temperature of the air from 6°C to 30°C

where does air travel to after the nasal cavity?

the nasopharynx

during sleeping, what can partially block the pharynx? (3)

- tongue

- uvula

- soft palate

what can partial blockage of pharynx do?

causes a turbulence in airflow, which is heard as snoring

where does air travel to after the nasopharynx?

oropharynx, laryngopharynx and then the larynx

what is the ventilation rate (V)?

volume of gas inhaled and exhaled from lungs in a given time period

what is the equation for ventilation rate? (V)

tidal volume x respiratory rate

what is the tidal volume?

volume of air inhaled and exhaled in a single breath

what is perfusion (Q)?

total volume of blood reaching pulmonary capillaries in a given time period

what is the ideal V/Q ratio and why?

1 - all the air inhaled gets to pulmonary capillaries

what is the average V/Q ratio for a human?

0.8

how does the V/Q ration change from apex to base of lung?

3.3 in apex and 0.63 in base

does ventilation or perfusion exceed in apex?

ventilation

does ventilation or perfusion exceed in base?

perfusion

why is the ratio higher in apex than base?

due to gravity

what are the differences in alveoli at apex and base of lung?

compliance (stretch)

what is the compliance like for basal alveoli?

smaller, so more compliant

what is the compliance like for apex alveoli?

larger, so less compliant

what happens in terms of perfusion if O₂ conc is low?

- vasoconstriction

- blood is diverted to better perfused regions of lung

called hypoxic pulmonary vasoconstriction