Respiratory Physiology

Question 1

What is pulmonary ventilation measured in

Answer 1

Litres/ minute

Question 2

What is minute ventilation (VE)

Answer 2

The volume of air brought into and out of the lungs per minute

Question 3

How do you calculate minute ventilation

Answer 3

Volume of air moved per breath x number of breaths per minute

Question 4

What is spirometry

Answer 4

A method used to monitor the amount of and/ or speed of movement of air that can be inhaled and exhaled

Question 5

What tidal volume

Answer 5

Volume of air moved per breath

Question 6

What is the conducting zone

Answer 6

The anatomic dead space where air does not reach the alveoli so no gas exchange occurs here

Question 7

What is the average volume of air in the conducting zone

Answer 7

150-200ml or about 30% of tidal volume

Question 8

What is alveolar ventilation

Answer 8

The amount of air reaching the alveoli

Question 9

What makes up the conducting zone

Answer 9

Trachea, primary bronchus, bronchus, bronchi, bronchioles

Question 10

What makes up the respiratory zone

Answer 10

Respiratory bronchioles, alveolar ducts and alveolar sacs

Question 11

Why does total minute ventilation not equate to alveolar ventilation

Answer 11

As not all the air we breath in reaches the alveoli, some remains in the conducting zone

Question 12

How is alveolar ventilation calculated per breath

Answer 12

Tidal volume- conducting zone volume

Question 13

How is alveolar ventilation calculated per minute

Answer 13

Minute ventilation- minute dead space ventilation

Question 14

What happens to alveolar ventilation during shallow breathing

Answer 14

Decreases as air enters and leave conducting zone without reaching respiratory zone

Question 15

What is inspiratory reserve volume (IRV)

Answer 15

The volume of air brought into the lung after normal inspiration

Question 16

How is IRV measured

Answer 16

1) inhale normally
2) inhale as deeply as possible
3) difference in volume= IRV

Question 17

What is the expiratory reserve volume (ERV)

Answer 17

The volume of air brought out of the lung after normal expiration

Question 18

How is ERV measured

Answer 18

1) Exhale normally
2) exhale as much as possible
3) difference= ERV

Question 19

What is forced vital capacity

Answer 19

Maximum air expired after maximum inspiration

Question 20

What is the residual lung volume

Answer 20

The volume of air in the lungs after max expiration

Question 21

Why is residual lung volume important

Answer 21

Key for continuous gas exchange as if this did not exist the alveoli would collapse

Question 22

What are the dynamic lung volumes

Answer 22

Dynamic ventilation and airflow velocity

Question 23

What is dynamic ventilation

Answer 23

Ventilation constrained by time

Question 24

What does dynamic ventilation depend on

Answer 24

Maximum lung volume (FVC), airflow velocity

Question 25

What is airflow velocity

Answer 25

The speed of moving a volume of air

Question 26

What does airflow velocity depend on

Answer 26

Resistance of respiratory passage and compliance if the chest and lung tissue

Question 27

What is airflow directly proportional too

Answer 27

Pressure gradient

Question 28

What is airflow inversely proportional to

Answer 28

Airway resistance

Question 29

What are obstructive pulmonary disorders

Answer 29

A disorder that obstructs airways so resistance is increased and airflow limited

Question 30

What are restrictive pulmonary disorders

Answer 30

Disorders that restrict the compliance of the chest wall, limiting airflow

Question 31

What is FEV1

Answer 31

Forced expiratory volume in one second after max inhale

Question 32

What is maximum voluntary ventilation

Answer 32

The amount of air that can be moved in and out of the lungs in one minute (a measure of dynamic lung volume)

Question 33

How is maximum voluntary ventilation measured

Answer 33

1) breathe as quickly and deeply as possible for 15 seconds 2) extrapolated to one minute

Question 34

Why does pulmonary minute ventilation increase during exercise

Answer 34

Increase in tidal volume and breath frequency

Question 35

Does tidal volume limit FVC in healthy individuals and why

Answer 35

No as tidal volume is only around 50-60% of FVC so other factors must be limiting

Question 36

How does ventilation increase during exercise

Answer 36

Diaphragm descends more and lung volume increases more due to more frequent and forceful contractions, larger pressure gradient, airways dilate so decreased airway resistance so faster airflow

Question 37

Why does gas exchange increase during exericse

Answer 37

Increased cardiac output to lungs, muscles use more oxygen and produce more CO2 during exercise so lower PO2 and higher PCO2 so higher pressure gradient

Question 38

What is the transit time

Answer 38

The length of time a RBC remains within a pulmonary capillary

Question 39

Why is a shorter transit time during exercise not a limiting factor of exercise capacity

Answer 39

As there is still enough time for gases to equilibrate between the alveoli and blood

Question 40

What is the feedforward mechanism that causes ventilation to increase during exercise

Answer 40

Neural outflow from the brain in anticipation of exercise

Question 41

Describe how neural outflow from the brain in anticipation of exercise causes an increase in ventilation

Answer 41

Exercise initiation stimulates respiratory neurons in the medulla to initiate an increase in ventilation abruptly

Question 42

What are the feedback mechanisms that cause an increase in ventilation during exercise

Answer 42

Chemoreceptors detect partial pressure of gases and pH in blood, sensory input from sensory receptors (proprioceptors) in joints, tendons and muscles and stretch receptors in the airways

Question 43

What mechanism causes the initial rapid increase of ventilation at the start of exercise

Answer 43

Feedforward mechanism via central command

Question 44

What causes the continued increase in ventilation as exercise continues

Answer 44

Combined feedforward and feedback mechanisms