External Respiration / Lungs 1. Respiration Involves the transport of gases from: the lungs to the blood the blood to the muscles the muscles to the mitochondria and back again Three types: External, Internal, and Gas Transport External also called Pulmonary Ventilation involves moving air in and out of the lungs additional functions warms the air - exposed to body humidifies the air - mucous membranes, especially in nasal passage filters the air - mucous membranes, cilia also, moves O2 and CO2 into and out of the blood pathway (20-22 subdivisions before exchange occurs) naso/oro pharynx naso has better effect on the additional functions pharynx larynx (vocal cords) air moves through loose vocal cords further relaxation occurs with increased air demands trachea contains cilia to provide extra filtering constantly sweeping dirty mucous upward bronchi 500-1000 sq. ft of surface area terminal bronchioles last subdivision that cannot exchange gases respiratory bronchioles at rest, 1/3 cup of blood on the membranes very thin, so very rapid diffusion alveolar ducts may or may not branch to alveoli alveoli (thin membraned sacs at the end of the ducts) moves O2 and CO2 into and out of the blood occurs at the pulmonary capillaries (very near the alveoli) right ventricle pulmonary aorta pulmonary arteries pulmonary capillaries pulmonary veins left atrium ring a bell ??? 2. Respiratory Control a. Overcome resistance movement of rib cage thoracic cavity movement - elastic lung movement - somewhat elastic general negative pressure in the lungs b. Mechanics of breathing: air is a gas under pressure always try's to maintain lowest possible pressure Boyle's Law: Pressure varies inversely with Volume air is forced into the lungs by outside pressure occurs when the pressure inside decreases lung pressure decreases when lung volume increases lung volume increases when: diaphragm contracts (lowers) intercostals contract (raise rib cage) c. Energy required to overcome resistance rest: small: 1-2 % of the O2 consumed intake requires the 1-2 %, exhale requires minimal (if at all - elastic) exercise: greater: 8-10 % of the O2 consumed reasons: amount of stretching is further (to move in more air) air is also forced out d. Control of respiration generally, the Medulla (Cardiac, Respiratory, and Vasomotor centers) at rest: respiration controlled by the ANS (or so it is believed) Chemoreceptors (aortic and carotid sinuses) low O2 or high CO2 however, can be overridden voluntarily with exercise: respiratory center begins to adjust respiration is believed to be controlled by: chemoreceptors low O2, high CO2 proprioceptors (responding to movement) temperature cerebral factors Herring-Bruener reflex's: inhibito-inspiration reflex (no, I did not make this up) visceral pleura have stretch receptors as they stretch, they send a signal to the brain this signal tells inspiration to stop excito-inspiration reflex (no, not this one either) muscles that control breathing relax reach low threshold level, stimulates breathing not the only factor in stimulating breathing e. Breathing Patterns Amount of Air moved per minute = Minute Ventilation Volume Is a function of : Size of the Breath (Tidal Volume - TV) times the Rate (BR) Can have equal MVV with: High TV and Low BR High BR and Low TV Which is better ? Need to first look at Resistance Airway - from the air moving through small rough openings Elastic - from stretching the lungs and the thorax Certainly, both are greater with a High TV However, one is actually More Efficient with a High TV this is due to the Anatomical Dead Space also called Residual Volume (RV) this is the air that is not expired Key is not MVV, but Alveoli Ventilation (AV) need fresh air to be in alveoli larger TV's result in a smaller RV (more fresh air) formula: AV = BR * (TV - RV) Overall, Max Exercise is best at 30 - 35 breaths per minute f. Ventilation Equivalence (VE) Is the amount of air required divided by the amount of O2 consumed Usually is constant from rest to low levels of exercise At moderate level, begins to increase at faster rate This is due to the formation of Lactic Acid 3. Respiratory Phenomena Stitch in the Side Pain in abdominal wall during prolonged exercise (running) Occurs due to fatigue of Breathing Muscles (Intercostals, Diaphragm) Usually occurs with new exercise regime (harder demands) Other possible causes: gas bubbles in the GI tract exercising too soon after eating lack of blood in the GI tract contraction of spleen expels RBC's Second Wind Text theorizes that has to do with warming-up Begin exercising and have greater O2 demands than supply Body then increases metabolism Respiration becomes more efficient shallow to deep breathing Cardiac output increases Redistribution of blood Rise in muscle temperature Fatigue begins, but dissipates as metabolism increases Proper warm-up lessens the negative supply time Probably true in many cases, but not always: Runners high is not a warm-up kind of thing Chemicals (Endorphins) are certainly involved may be the same thing here Exercise Induced Asthma (EIA) Bronchioles constrict with imposed demands Common, not dangerous Exercise (and inhalers) are recommended 4. Unusual Respiratory Maneuvers Hypoventilation Very slow breathing that results in Hypercapnia the accumulation of CO2 in the arteries Hyperventilation Rapid breathing that results in Hypocapnia CO2 is blown off faster than is produced Allows person to hold breath longer Hypercapnia is the driving force in breathing Valsalva Maneuver Holding breath in while pressure is pushing it out Used by weightlifter for maximal lifts Probably increases blood flow through muscles Also, may support trunk better Potentially hazardous: Pass out Aneurysm 5. Smoking Long Term Effects: recently shown to be directly linked to lung cancer Short Range Effects Will NOT damage strength, power, and speed Will damage endurance results (same as air pollution) irritating substance in smoke irritates lining of lungs mucous comes up and partially blocks the air flow CO in smoke/smog reduces the OC carrying capacity of hemoglobin CO2 attaches to the globin portion, whereas O2 attaches to the hemes CO also attaches to the hemes, Heme has a much greater affinity for CO (200-250 times) 1 pack of cigarettes reduces O2 capacity by 10 % Effects of Nicotine Recently shown to be addictive (and manipulated) Causes Vasoconstriction Increases BP Decreases Blood Flow Volume (O2 availability)