Respiratory Function, Breathing, Respiration BI 233 Exercise 40 Mechanics of Breathing • • • • Air moves from regions of higher pressure to regions of lower pressure. The lungs fill with air or deflate due to changes in air pressure. During inspiration the diaphragm contracts (with external intercostals) increasing the volume in thoracic cavity causing a decrease in pressure in the lungs which causes air to move into the lungs. When the diaphragm relaxes the size of thoracic cavity decreases causing increase in pressure and therefore causing expiration. Inspiratory Muscles Diaphragm: Primary Inspiratory muscle 2. External intercostal muscles Forced inhalation: 1. Sternocleidomastoid Scalenes Serratus anterior Pectoralis minor Expiratory Muscles Normal exhalation is a passive process, resulting from the elastic recoil of the lungs. Forced exhalation Internal intercostals muscles Transverses thoracic Abdominal muscles Clinical Application • • • • • Adequate pulmonary ventilation is critical Reduction in pulmonary ventilation can cause increased CO2 (hypercapnia) producing acidosis Increased pulmonary ventilation can lead to a reduction in CO2 (hypocapnia) producing alkalosis. Changes in CO2 concentrations can alter breathing rates *When doing experiment breathing into a paper bag make sure to have a spotter for the student who is breathing into the bag The Bicarbonate Buffer System Definitions • • • Pulmonary Ventilation is the movement of air into and out of the lungs and the exchange of gases across the respiratory membrane The ventilation rate is the number of breaths per minute The pulmonary volume is the amount of air inhaled and exhaled with each breath Measurement of Relaxed Breathing Rate • • • • • Calculate your lab partner’s relaxed breathing rate Have partner read lab exercise while you count the number of breaths for 2 minutes. Divide by 2 = BPM Record your results Do this again but have lab partner do strenuous exercise for 2 minutes and then count the number of breaths. Pulmonary Volumes Pulmonary volumes are the amount of air that flows into or out of the lungs during a particular event. Tidal Volume(TV): amount of air inhaled or exhaled with each breath under resting conditions (300-500ml) *The numbers given for volumes and capacities are averages and vary greatly between individuals Pulmonary Volumes • • • Inspiratory Reserve Volume (IRV): Amount of air that can be forcefully inhaled after a normal tidal volume inhalation (3100ml) Expiratory reserve volume (ERV): amount of air that can be forcefully exhaled after a normal tidal volume exhalation (1200ml) Residual Volume: Air left in lungs (1000ml) Capacities Lung capacities are calculated by summation of volumes 1. Vital Capacity (VC): Maximum amount of air that can be exhaled after a maximal inspiration (4800ml) 2. Total Lung Capacity 3. Inspiratory Capacity • Calculate your volumes and capacities including the percent of expected VC • Effect of pCO2 levels on the Respiratory rate 1. 2. 3. 4. 5. Use our beginning respiratory rate (unless different lab partner is being tested) Have partner take rapid, deep breaths until they tire (couple minutes max) Record the respiratory rate Then have your lab partner breathe in and out into a paper bag for one to two minutes. Remove bag and record their respiratory rate on the data sheets. Other Exercises 1. 2. 3. Calculate your minute ventilation (TV X # of breaths per min.) Do flow and resistance exercise and be able to describe the relationship between these. Listen to your lab partners respiratory sounds with the stethoscope Cardiopulmonary Resuscitation CPR: typically used for people suffering from a heart attack (myocardial infarct), drug overdoses, drowning or trauma and obstruction of airways. Uses chest compressions of 100 times per minute on the body of the sternum. Physiology of Exercise and Pulmonary Health Exercise 41 Exercise • • Aerobic exercises increase heart rate and breathing rates at moderate levels for extended periods of time. Anaerobic exercises result in the consumption of available oxygen faster than it can be supplied to the muscle tissue Percent Forced Expiratory Vital Capacity (FEV1/VC%) • Indications of health can be roughly correlated with the amount of air expelled from the lungs in one second. • Expressed as a percent when compared to a person’s vital capacity (VC). • Should be approx 75% Pulmonary Obstruction COPD = Chronic Obstructive Pulmonary Disease Occurs when the respiratory passages are narrowed. Can be caused by excess mucus (such as asthma) or inflammation (such as bronchitis). Most COPD is caused by smoking. VC is normal but FEV1/VC% is low. Simply – with obstruction it takes longer to exhale Pulmonary Restriction - Fibrosis Occurs when the lungs cannot fully inspire or expire the full volume of air - FEV1 is reduced Vital Capacity (VC) is reduced Caused by fibrosis of the lungs (cystic fibrosis or from asbestos) or adhesions of the lung to the chest (emphysema) FEV1/VC% is normal Usually, the cause of pulmonary fibrosis is the inhalation of harmful substances. Possible causes of pulmonary fibrosis are: Inhalation asbestos, rock dust, metal powder, mold, dust Tuberculosis (TB). Severe pneumonia. Certain medications and poisons. Irradiation. Autoimmune diseases. Sarcoidosis. FEV1 Forced Expiratory Volume = volume of air exhaled under forced conditions in the first one second FEV1 /VC Percent Forced Vital Capacity = the ratio of FEV1 to VC. In healthy adults this should be approximately 70– 85% (declining with age). In obstructive lung disease, (asthma, COPD, chronic bronchitis, emphysema) the FEV1 is reduced because of increased airway resistance to expiratory flow. Thus, the FEV1/FVC ratio will be reduced. In restrictive lung disease, (fibrosis) the FEV1 and VC are equally reduced. Thus, the FEV1/VC ratio should be approximately normal. Harvard Step Test • • • • • Was developed to determine a person’s physical fitness. We do not have the steps recommended in lab manual but you can go outside and walk up and down stairs for 3-5 minutes. Subject then rests for 30 seconds Then partner takes pulses every 30 seconds Calculate PFI using your lab manual: Body Mass Index BMI is a general guide to fitness BMI= Weight in pounds/(height in inches)2 X 703 or BMI= Mass(kg)/ Height (M)2 or Use chart Waist/Hip Ratio WHR: According to the American Heart Association, people who carry more weight in their waist region are more at risk for health problems. WHR= Circumference of waist/Circumference of hips Lab Activities Make sure that you understand today’s activities for the quiz next week.