PULMONARY FUNCTION &
RESPIRATORY ANATOMY
KAAP310
Respiratory Anatomy
◦ Larynx
◦ Hyoid bone
◦ Thyroid cartilage
◦ Lateral cricothyroid
ligaments
◦ Cricoid cartilage
http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&%20Physiology/2020/2020%20Exam%20Reviews/Exam%203/larynx%20figure.jpg
Anatomy of the Lung
◦ Trachea
◦ Bronchi
◦ Upper lobe
◦ Middle lobe
◦ Lower lobe
◦ Diaphragm
http://www.cancer.gov/Common/PopUps/popDefinition.aspx?id=270740&version=Patient&language=English
Anatomy of the Lung
◦ Terminal bronchiole
◦ Respiratory bronchiole
◦ Pulmonary vein
◦ Pulmonary artery
◦ Alveoli
◦ Capillary bed
http://cnx.org/content/m46548/latest/2309_The_Respiratory_Zone.jpg
Surfactant
◦ A detergent-like complex of lipids
and proteins produced by alveolar
cells.
◦ Decreases the surface tension of the
fluid that lines the walls of the alveoli.
◦ Less energy is required for breathing.
◦ Prevents alveoli from collapsing.
http://hyperphysics.phy-astr.gsu.edu/hbase/fluids/imgflu/alveolicut.gif
Blood Circulation
◦ The heart pumps deoxygenated blood to the
pulmonary capillaries for gas exchange to occur
between blood and alveoli – air sacs in the lungs.
◦ This is known as the pulmonary circulation.
◦ Oxygenated blood returns to the heart, where it is
pumped out through the aorta by the left ventricle
to the rest of the body (systemic circulation).
◦ Red blood cells (erythrocytes) transport oxygen in
the body.
◦ RBC concentration is higher in those living at high
altitudes.
http://www.lenoircc.edu/disted/med/medgif/med12111c.gif
Inspiration and Expiration
◦ During inspiration, the
diaphragm and external
intercostals contract to
make the thoracic cavity
larger.
◦ Active process – requires
muscle action.
◦ During expiration, the
diaphragm and external
intercostals relax and the
thoracic cavity becomes
smaller.
◦ Passive process at rest
◦ Active process during
exercise
http://3.bp.blogspot.com/-oBzLa5UeiQM/TZyfGjrEHpI/AAAAAAAAAAQ/_IrQb_OSNSc/s1600/inspirationexpiration.jpg
Respiratory Volumes
◦ Tidal Volume (VT) – the amount of air that moves into and out of the lungs
during normal, quiet breathing (~500 ml).
◦ Inspiratory Reserve Volume (IRV) – the amount of air that can be inspired
forcibly beyond the tidal volume (2100-3200 ml).
◦ Expiratory Reserve Volume (ERV) – the amount of air that can be expelled
from the lungs after a normal tidal volume expiration (1000-1200 ml).
◦ Residual Volume (RV) – the amount of air that remains in the lungs even after
the most strenuous expiration (1200 ml).
Respiratory Capacities
◦ Inspiratory Capacity (IC) – the amount of air that can be inspired after a normal
tidal volume expiration.
◦ IC = VT + IRV
◦ Functional Residual Capacity (FRC) – the amount of air remaining in the lungs
after a normal tidal volume expiration.
◦ FRC = RV + ERV
◦ Vital Capacity (VC, also called FVC, forced vital capacity) – the total amount of
exchangeable air (~4800 ml).
◦ VC = VT + IRV + ERV
◦ Total Lung Capacity (TLC) – the sum of all lung volumes (~6000 ml).
◦ TLC = VT + IRV + ERV + RV
Spirogram
Rate of
breathing and
tidal volume
increase
during
exercise.
http://www.austincc.edu/apreview/NursingPics/RespiratoryPics/Picture16.jpg
Dead Space
◦ Dead Space – some of the inspired air fills the
conducting respiratory passageways and never
contribute to gas exchange in the alveoli.
◦ Anatomical Dead Space (VD)– volume in conducting
zone (~150 ml).
◦ Alveolar Dead Space – volume of air in alveoli that
have ceased to act in gas exchange (due to alveolar
collapse or obstruction by mucus, for example).
◦ Total Dead Space = anatomical dead space plus
alveolar dead space.
http://web.squ.edu.om/med-Lib/MED_CD/E_CDs/anesthesia/site/content/figures/2015f21.gif
Additional Terms
Alveolar Volume:
VA = volume of gas in the alveoli that participates in gas exchange.
VA = VT – VD
Breathing Frequency:
f = number of breaths per minute.
Minute Ventilation = Expired Ventilation:
𝑉𝐸 = total volume of air expired per minute. (Notice the over-dot.)
𝑉𝐸 = 𝑓 × 𝑉𝑇
Alveolar Ventilation:
𝑉𝐴 = volume of air fresh air reaching alveoli every minute. (Notice over-dot.)
𝑉𝐴 = 𝑓 × 𝑉𝐴 = 𝑓 × 𝑉𝑇 − 𝑉𝐷
Spirometry
◦ Measurement of pulmonary function that is common in clinical medicine
◦ Involves measurement of the volume and rate of expired airflow
◦ FVC – forced vital capacity – amount of gas expelled when a
person takes a deep breath and then forcefully exhales maximally
and as rapidly as possible.
◦ FEV1 (forced expired volume in one second) – the amount of air
exhaled in the first second of a maximal exhalation.
◦ Normally 75-85% of VC
◦ FEV1 /FVC ratio – used to assess and diagnose airway disorders
◦ Clinically significant when <75%
https://www.nhlbi.nih.gov/health/health-topics/images/spirometry.jpg
Why do spirometry?
◦ It is used to diagnose airway
disorders.
◦ Obstructive airway diseases –
asthma, chronic bronchitis,
emphysema, chronic obstructive
pulmonary disease (COPD), etc.
◦ Reduced FEV1
◦ Normal FVC
◦ Reduced FEV1/FVC ratio
◦ Restrictive airway diseases – kyphoscoliosis, neuromuscular disease,
pulmonary fibrosis, etc.
◦ Reduced FVC
◦ Reduced FEV1
◦ FEV1/FVC ratio may be normal, or not
http://www.rationalprescribing.com/images/illustrations/obstructive_vs_restrictive_lung_disease.gif
Experiment 1
◦ Using the handheld spirometers, ONE person from each group will be the
subject, who will wear a nose piece to prevent air from escaping through the nasal
passages.
◦ Subject will take a maximal inspiration, then quickly place their mouth around the
mouthpiece creating a tight seal, and then exhale AS QUICKLY AND AS
FORCEFULLY AS POSSIBLE until he/she cannot exhale anymore.
◦ The subject will perform 3 trials, allowing rest time between trials.
◦ Record your FVC and FEV1 values in the data sheet.
◦ Calculate your FEV1/FVC ratio
Spirometry Reference Value Calculator
◦ Go to the following website:
http://www.cdc.gov/niosh/topics/spirometry/RefCalculator.html
◦ Select “Hankinson 1999” as your reference source.
◦ Enter your gender, race, age, and height and the highest numbers you recorded
for FVC and FEV1 (leave the other boxes blank).
◦ Click calculate.
◦ Fill in the table in the lab packet.
◦ Answer and turn in the lab questions – either before the end of lab or next week.
Equations to Remember
𝑉𝐸 = 𝑓 × 𝑉𝑇
Minute Ventilation = breathing frequency × tidal volume
VT = V A + VD
Tidal volume = alveolar volume + dead space volume
𝑉𝐴 = 𝑓 × 𝑉𝑇 − 𝑉𝐷
Alveolar Ventilation Rate = breathing frequency × alveolar volume
Therefore, using the equation relating tidal volume and alveolar volume,
AVR = breathing frequency × (tidal volume – dead space volume)
Sample Calculations with the
Equations to Remember
A subject has a tidal volume of 700 mL (VT =700 mL) and is breathing 14
times per minute (f=14 breaths/min). What is her minute ventilation?
𝑚𝐿
𝑏𝑟𝑒𝑎𝑡ℎ
𝑚𝐿
𝐿
𝑉𝐸 = 𝑓 × 𝑉𝑇 = 14
× 700
= 9800
= 9.8
𝑏𝑟𝑒𝑎𝑡ℎ
𝑚𝑖𝑛
𝑚𝑖𝑛
𝑚𝑖𝑛
The subject just described has a dead space volume of 150 mL. What is her
alveolar ventilation rate?
𝑚𝐿
𝐿
𝑉𝐴 = 𝑓 × 𝑉𝑇 − 𝑉𝐷 = 14 × 700 − 150 = 7700
= 7.7
𝑚𝑖𝑛
𝑚𝑖𝑛