3 Anatomy of the Lung Trachea Bronchi Upper lobe Middle lobe Lower lobe DiaphragmLarynxLungsHyoid boneThyroid cartilageLateral cricothyroid ligamentsCricoid cartilageTracheaBronchioleRespiratory bronchioleTerminal bronchioleUpper lobeMiddle lobeLower lobePulmonary veinPulmonary arteryAlveoliCapillary bed
4 Anatomy of the Lung Terminal bronchiole Respiratory bronchiole Pulmonary veinPulmonary arteryAlveoliCapillary bed
5 SurfactantA 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.Decreases the surface tension of water in fluid that lines the walls of the alveoli, prevents the alveoli from collapsing.Surfactant is a surface active lipoprotein complex formed by type 2 alveolar cellsIt contribute to its general compliance. It is important because it stabilize the alveoliActivity 3 test role of surfactant. How respiratory rate change with surfactant.
6 Blood CirculationThe 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.
7 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.
8 Respiratory VolumesTidal 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 ( ml).Expiratory Reserve Volume (ERV) – the amount of air that can be expelled from the lungs after a normal tidal volume expiration ( ml).Residual Volume (RV) – the amount of air that remains in the lungs even after the most strenuous expiration (1200 ml).RV helps to keep the alveoli open and prevent lung collapse.
9 Respiratory Capacities Inspiratory Capacity (IC) – the amount of air that can be inspired after a normal tidal volume expiration.IC = TV + IRVFunctional Residual Capacity (FRC) – the amount of air remaining in the lungs after a normal tidal volume expiration.FRC = RV + ERVVital Capacity (VC) – the total amount of exchangeable air (~4800 ml).VC = TV + IRV + ERVTotal Lung Capacity (TLC) – the sum of all lung volumes (~6000 ml).TLC = TV + IRV + ERV + RV
10 Spirogram Note: these values will change acutely with exercise. Rate of breathing and tidal volume increase.
11 Dead SpaceDead 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.
12 Additional TermsAlveolar Volume (VA) – volume of gas in the alveoli that participates in gas exchange.VA = VT – VDBreathing Frequency (f) – number of breaths per minute.Minute Ventilation/Expired Ventilation ( E) – total volume of air expired per minute.E = f x VTAlveolar Ventilation ( A) – volume of air that reaches the alveoli every minute.A = f x VA = f x (VT – VD)The dot over the V indicates that it is a measure of volume per unit time (ml/min)
13 SpirometryMeasurement of pulmonary function that is common in clinical medicineInvolves measurement of the volume and rate of expired airflowFVC – forced vital capacity – amount of gas expelled when aperson takes a deep breath and then forcefully exhales maximallyand as rapidly as possible.FEV1 (forced expired volume in one second) – the amount of airexhaled in the first second of a maximal exhalation.Normally 75-85% of VCFEV1 /FVC ratio – used to assess and diagnose airway disordersClinically significant when <0.75https://www.nhlbi.nih.gov/health/health-topics/images/spirometry.jpg
14 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.FEV1/FVC <70% implies obstructive.Hallmark of obstructive is slowing of expiratory flow, low proportion of the FVC is expired in the first second and the ratio is reduced.Restrictve, the FEV1 and FVC are both reduced, but in proportion, so the ratio remains normal.
15 Experiment 1Using 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
16 Spirometry Reference Value Calculator Go to the following website: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.
17 Equations to Remember & Sample Calculations VT = VA + VD𝑉 𝐴 = 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/minuteIf a person has a breathing frequency of 14 b/min and tidal volume of 425 ml, what is their alveolar ventilation in liters?𝑉 𝐴 = f x (VT - VD) = 14 breaths/min * (425 mL -150 mL)= 3850 mL/min = 3.9 L/min