Pulmonary and Alveolar Ventilation

Question 1

What is Minute Ventilation (Vl)

Answer 1

The volume of air passing into or out of the lungs per minute

Question 2

What is the Tidal Volume (VT)

Answer 2

The volume of air that is moved between either inspiration or expiration

Question 3

What is the approximate resting tidal volume

Answer 3

0.5L/breath

Question 4

What is Inspiratory reserve volume (IRV)

Answer 4

The maximum volume of air inspired above the tidal volume

Usually 2-3L > TV

Question 5

What is the Expiratory reserve volume (ERV)

Answer 5

The maximum volume of air expired after the tidal volume expiration
Usually 1-1.5L > TV

Question 6

What is the Vital Capacity (VC)

Answer 6

This is the total amount of air that can be moved in one breath from full inspiration to full expiration

Question 7

What equation can be formed using IRV, VC, TV and ERV to measure total volume of exhaled air from maximal inspiration to maximal expiration

Answer 7

VC = TV + IRV + ERV

Question 8

What is the Functional Residual Capacity (FRC)

Answer 8

This is the resting volume of the lung (usually like 3L)

Question 9

What is the residual volume of the lungs

Answer 9

This is the volume left in the lungs after you breathe out as hard as possible.

Question 10

What are some factors that determine the static volumes of the lungs

Answer 10

• Anatomy (size)
• Elasticity of lungs and chest wall
• Strength of respiratory muscles

Question 11

What is spirometry a measure of

Answer 11

A measure of the amount of and/or speed of air that can be inhaled

Question 12

What can Rolling Seal Water Filled spirometers measure

Answer 12

Tidal Volume
Vital Capacity
Inspiratory and Expiratory reserve Volumes

Question 13

What can a turbine respirometer measure

Answer 13

Forced Expiratory Volume in one second

Peak Expiratory Flow (PEFR)

Question 14

Why can’t RV and FRC be measured

Answer 14

They cannot be breathed out

Question 15

What methods can be used to measure the RV or FRC

Answer 15

Helium Dilution

Bag containing known volume of oxygen

Question 16

How does a rolling seal water filled spirometer work

Answer 16

closed space and subject breathes into it and movements are recorded as changes in lung volume on moving chart

Question 17

What 3 pressures are responsible for pulmonary ventilation

Answer 17

Atmospheric
Intra-alveolar
Intrapleural

Question 18

Define atmospheric, intra-alveolar and intrapleural pressure

Answer 18

Atmospheric - pressure in the air outside the body
Intra-alveolar - Pressure inside the alveoli of the lungs
Intrapleural - Pressure within the pleural cavity

Question 19

Describe the pressure changes during breathing

Answer 19

Start of inspiration intra alveolar and pleural pressures decrease
Gas flows in and lung volume increases
Airflow stops when intraa-alveolar and atmospheric become equal
Exhalation = diaphragm moves up, intrapleural increases (less neg.) alveolar becomes positive and air flows out of lung

Question 20

What is anatomical dead space in the upper respiratory tract and lungs

Answer 20

System of tubes connecting alveoli to atmosphere doesn’t do gas exchange so is dead space
Anatomical dead space is the volume of air in the mouth, pharynx, trachea and bronchi up to the terminal bronchioles

Question 21

What is alveolar dead space

Answer 21

shows only with age or disease and is when alveoli have insufficient blood supply to act as effective respiratory membranes

Question 22

what is physiological dead space

Answer 22

Anatomic + Alveolar dead space

Question 23

Why is high frequency artificial respiration used in trauma victims

Answer 23

To avoid excessive movements of the chest wall.

Adequate alveolar ventilation can occur with small tidal volumes as long as frequency is high

Question 24

When measuring alveolar ventilation in mL/min what equation is needed

Answer 24

(tidal volume - Anatomical dead space) x respiratory rate

Question 25

What is the equation for respiratory exhchange ratio

Answer 25

Ratio of CO2 output divided by O2 uptake

given symbol “R”

Question 26

What values of Respiratory exchange ratios can indicate carbohydrate and fat use

Answer 26

around 1 = carbs

around 0.7 = fats

Question 27

Why can the respiratory exchange ratios indicate which fuel is being used

Answer 27

Ratio depends on oxygen already in molecule being oxidised, the more already in the molecule the less has to be brought in.

Question 28

Name two factors than can changes respiratory quotient (RQ), which is basically respiratory exchange ratio

Answer 28

Exercise - Lactic acid enters blood, forms carbonic acid with bicarbonate and frees lots of CO2. RQ can exceed 2
Diabetics - shows low RQ due to poor metabolism of carbs and increased metabolism of fats.