Respiratory

Question 1

Which are inspiratory and expiratory muscles?

Answer 1

Inspiratory: diaphragm; during exercise/ stress- accessory muscles & ext intercostals.

Expiratory: passive- elastic recoil of chest wall. Stress- abdominal muscles & int intercostals (ribs down & in).

Question 2

Compliance

Answer 2

Describes distensibility of lungs & chest wall —> slope of the pressure-volume curve (change in volume for a given change in pressure).

C= V/P
C- compliance (ml/ mmHg)
V- vol (ml)
P- pressure (mmHg)-refers to the transmural/ transpulmonary pressure

Question 3

Transpulmonary pressure is

Answer 3

Alveolar pressure minus intrapleural pressure.

-intrapleural pressure expands lungs.
+ intrapleural pressure collapses lungs.

Compliance greatest in middle range of pressures: most distensible.
Compliance decreases at low & high lung volumes.

Question 4

TV, TLC, FRC in healthy young adult

Answer 4

TV ~500ml
TLC ~6000ml
FRC ~2500ml (FRC= RV + ERV). Compliance greatest at FRC.

Question 5

Normal terminal bronchioles (1mm) characteristically

Answer 5

Offer lower resistance to airflow as lung volume increases. Has abundant SM, and collapse with forced expiration. Do NOT participate in gas exchange.

Question 6

Normal values of pulmonary vascular resistance

Answer 6

25-125 dyn.sec/ cm5.

Resistance is increased when PEEP applied (shunt) and decreased by NO inhalation.

Question 7

Airway resistance is expressed as?

Answer 7

cm H2O/ L/ s

Question 8

Quiet breathing at rest, O2 in expired air is greater or less than that in alveolar air?

Answer 8

Greater

Question 9

In control of breathing, what mediates ventilators response to acidaemia?

Answer 9

Peripheral chemoreceptors

Question 10

What happens to breathing control with denervation of carotid and aortic bodies?

Answer 10

Ventilatory response to hypoxia could be abolished