PULMONARY FUNCTION

&RESPIRATORY

ANATOMYKAAP 310

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 transport oxygen in the body.◦RBC concentration is known to increase due to

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 quiet expiration, the diaphragm and external intercostals relax and the thoracic cavity becomes smaller.◦ Passive process, when

at rest.

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 = TV + 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) – the total amount of exchangeable air (~4800 ml).◦VC = TV + IRV + ERV

◦Total Lung Capacity (TLC) – the sum of all lung volumes (~6000 ml).◦TLC = TV + IRV + ERV + RV

Spirogram

http://www.austincc.edu/apreview/NursingPics/RespiratoryPics/Picture16.jpg

◦Note: these values will change acutely with exercise.◦ Rate of breathing and

tidal volume increase.

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.

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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 ( E) – total volume of air expired per minute.◦ E = f x VT

◦Alveolar Ventilation ( A) – volume of air that reaches the alveoli every minute.◦ A = f x VA = f x (VT – VD)

V

V

VV

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 <0.75

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.◦FVC normal, FEV1 below normal.

◦The ratio FEV1/FVC ratio is also below normal.

◦Restrictive airway diseases – kyphoscoliosis, neuromuscular disease, pulmonary fibrosis, etc.◦FVC and FEV1 are both below normal.

◦The ratio FEV1 /FVC is approximately normal.

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, FEV1, and peak flow 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 & Sample Calculations◦VT = VA + VD

◦ = f x (VT - VD)

◦If a person has a minute ventilation of 22 L and a Vt of 1.1L, how many times per minute will they breath? 22L/min / 1.1 L = 20 breaths/minute

◦If a person has a breathing frequency of 14 b/min and tidal volume of 425 ml, what is their alveolar ventilation in liters? = f x (VT - VD) = 14 breaths/min * (425 mL -150 mL)

= 3850 mL/min = 3.9 L/min