The three components of the respiratory system External respiration Gas transport Internal respiration
The three functions of the respiratory system External respiration or pulmonary ventilation Gas transport and distribution from the lungs to the tissues via the blood Internal or tissue respiration
Sequence of air flow in external respiration 1.Through nose 2.Into nasal cavity 3.Past turbinates 4.Through nasopharynx 5.Past the glottis 6.Into trachea 7.To bronchi 8.To lungs 9.To smaller bronchi 10. To bronchioles 11. To terminal bronchioles 12. To respirator bronchioles 13. Alveolar ducts 14. Alveoli Visit the AACVPR—American Association of Cardiovascular and Pulmonary Rehabilitation at www.aacvpr.org and the National Jewish Medical and Research Center at www.njc.org/main.htmlwww.njc.org/main.html
The respiratory system, showing the respiratory passages and the function of the alveolus to oxygenate the blood and to remove carbon dioxide.
Mechanics of lung ventilation Inspiration –The diaphragm descends and the external and anterior internal intercostal muscles raise the ribs –Volume of lungs increases –Lowers pressure within the lungs (creates a pressure gradient) –Air moves into the lungs Expiration –The diaphragm and intercostals recoil to their resting length –Recoil creates a higher-than-atmosphere pressure in the lungs –Pressure gradient moves air out of the lungs
Lung ventilation during exercise Scalene and sternocleidomastoid muscles help lift ribs in inspiration Abdominal muscles aid in expiration Raise intra-abdominal pressure Draw lower ribs downward and medially
The four primary lung volumes Tidal volume Inspiratory reserve volume Expiratory reserve volume Residual volume Visit the American Lung Association at www.lungsusa.orgwww.lungsusa.org
Respiratory control Input to respiratory center comes from Neural input within the brain Neural input from muscles and joints Humoral input
Breathing patterns during exercise Rate and depth Type of exercise Diaphragmatic versus costal breathing Oral versus nasal breathing
The ventilation equivalent The number of liters of air breathed for every 100 ml of oxygen consumed. At rest, approximately 25.4 liters of air must be inspired for a person to consume 1 liter of oxygen.
Respiratory phenomena Stitch in the side –Perhaps caused by ischemia of the diaphragm or intercostal muscles Second wind –Occurs when body makes metabolic adjustments to exercise Exercise-induced asthma (EIA) –Swimming well tolerated by asthmatics –Continuous running most likely to trigger
Respiratory phenomena (cont.) Hypoventilation –Typical of airway obstruction –Metabolism occurring at faster rate than lung ventilation Hyperventilation –Lung ventilation rate is greater than metabolism –Decreasing quantities of CO 2 (hypocapnia) –Used by swimmers
Training and pulmonary function Endurance training –Decreases functional residual capacity –Decreases residual volume –Decreases ratio of residual volume/total lung capacity –Increases vital capacity Respiratory muscle fatigue –Lack of sufficient blood flow to provide adequate oxygen and remove metabolic byproducts –Limits exercise performance
Effects of exposure to ozone on athletic performance Decreases distance running ability Reduces VO 2 max Decreases maximum ventilation rate Causes shallow rapid breathing during submaximal exercise as well as a reduction in tidal volume
Effect of endurance training on respiration Makes breathing more efficient Reduces metabolic acidosis Increases oxidative capacity of the respiratory muscles Decreases functional residual capacity Decreases residual volume Decreases the ratio of residual volume/total lung capacity Increases vital capacity
Gas transport Three processes occur between lung ventilation and tissue respiration: 1.Diffusion of oxygen across the wall of the alveolus and the wall of the capillary 2.Transport of oxygen in the blood to the capillary bed of the muscles 3.Diffusion of oxygen across the capillary wall to the active muscle fibers
Percentage and partial pressures of O 2 by altitude.
Some basic properties of gases Composed of molecules that are in constant motion at high velocities Have no definite shape or volume, but conform to that of the container Pressure results from the constant impact of molecules on the wall of the container Pressure can be increased by confining gas to a smaller volume or increasing the activity of the molecules Heat increases the molecular velocity, which increases pressure
Composition of respiratory gases Atmospheric air composed mainly of –nitrogen, –oxygen, –and carbon dioxide
Diffusion gradients for oxygen 60 mm Hg for carbon dioxide 5 to 6 mm Hg
Gas transport by the blood Oxygen –Blood transports 20 volume percent of oxygen, 100 times a much as will dissolve in solution –Hemoglobin binds with oxygen Carbon dioxide 1.Diffuses across cell membrane into the tissue fluid then across capillary wall into blood plasma 2.Most diffuses from plasma into red blood cell 3.Red blood cells transport the carbon dioxide
Oxygen dissociation curve Amount of oxygen released from hemoglobin as a result of changing carbon dioxide levels in the tissues Curve is steep when the partial pressure of oxygen is low
The coefficient of oxygen utilization during exercise The proportion of oxygen transported by the blood that is given off to the tissues –During resting conditions –During exercise
The two processes involved in the control of acid-base balance Buffer systems –Carbonic acid bicarbonate system –Blood proteins –Hemoglobin and oxyhemoglobin Physiological changes –In respiratory function –In kidney function
The acid-base balance limits performance because When exercise intensity increases beyond aerobic capacity, lactic acid becomes the end product of metabolism The body’s ability to buffer lactic acid plays a large role in determining the end point of anaerobic activity
Effect of exercise on lung diffusion The diffusion of oxygen from the alveoli to the pulmonary capillaries increases in direct proportion to the intensity of the exercise
Breathing oxygen-enriched gas before or after exercise to improve performance or aid recovery Not useful physiologically May have a psychological effect if the athlete believes the oxygen helps.
Limits on the maximal oxygen consumption rate (VO 2 max) During activities involving large muscle groups: –Cardiac output During activities that involve only arms or only legs: –Muscular blood flow –Oxygen utilization