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Ch 42: Gas Exchange and the Respiratory System

Ch 42: Gas Exchange and the Respiratory System. Functions of the Respiratory System:. Air distribution / gaseous exchange; 2) Filters, warms & humidifies air we breathe; 3) Respiratory organs influence speech; 4) Helps maintain body’s pH; 5) Makes sense of smell possible.

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Ch 42: Gas Exchange and the Respiratory System

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  1. Ch 42: Gas Exchange and the Respiratory System

  2. Functions of the Respiratory System: • Air distribution / gaseous exchange; 2) Filters, warms & humidifies air we breathe; 3) Respiratory organs influence speech; 4) Helps maintain body’s pH; 5) Makes sense of smell possible.

  3. **Gas exchange supplies O2 for cellular respiration and disposes of CO2.

  4. Respiratory surface = surface where gas exchange with the respiratory medium (source of oxygen) occurs *the resp. medium for: -aquatic organisms = water -terrestrial organisms = air

  5. LUNGS • LUNGS = the respiratory adaptation of most terrestrial vertebrates **advantages of air as the resp. medium: 1) higher O2 concentration 2) O2 & CO2 diffuse faster in air than in water.

  6. Mammalian Respiratory System: Nostrils (air is filtered by hairs and cilia, and warmed Nasal cavity and moistened) Pharynx (throat) Glottis / epiglottis

  7. Mammalian Respiratory System: Larynx (voice box) – vocal chords here Trachea (cartilage-lined windpipe) Bronchi Bronchioles

  8. Mammalian Respiratory System: Alveoli (humans have approx. 300,000,000 of these microscopic air sacs; walls are only 1-2 cells thick.) Blood via the capillaries!

  9. ALVEOLI • Lined with thin layer of epithelium which serves as the respiratory surface; **epithelium is a tissue type that covers body surfaces and lines passages • Oxygen dissolves in moist film covering epithelium & diffuses across to the capillaries covering each alveolus; • Carbon dioxide moves in opposite direction

  10. *the amount of air inhaled and exhaled depends upon size, activity level and state of health. TIDAL VOLUME = volume of air an animal inhales & exhales with each breath during normal, quiet breathing (Average = 500 mL in humans)

  11. VITAL CAPACITY = maximum air volume that can be inhaled & exhaled during forced breathing (Average = 3400-4800 mL in humans) -loss of lung elasticity may result in collapse of bronchioles during exhalation -emphysema causes a decrease in vital capacity • RESIDUAL VOLUME = amt. of air that remains in lungs after forced exhalation (makes it easier to inflate lungs during next inhalation)

  12. Vital capacity

  13. Measuring Your Vital Capacity! • Turn dial to “0” • Put on a mouthpiece • Take your deepest inhalation possible • Exhale! Exhale! Exhale! (until you feel as if there isn’t 1 more molecule of air left •  The air that is left, is your residual volume

  14. CONTROL OF BREATHING -breathing is an automatic action -we inhale when nerves in the “breathing centers” of the medulla oblongata & pons send impulses to the rib muscles and diaphragm stimulating the muscles to contract (pH levels regulates medulla) -when muscles contract, the volume of the chest cavity expands, pressure decreases, air from outside rushes in -this happens approx. 10-14 times per minute “Negative Pressure Breathing”

  15. CONTROL OF BREATHING -medulla control center monitors the pH of the cerebrospinal fluid bathing the brain; -as blood CO2 concentrations increase, the pH drops (CO2 combines with water to form carbonic acid); -when the medulla senses the drop in pH, the rate & depth of breathing are increased & as a result, excess CO2 is removed in the exhaled air

  16. CONTROL OF BREATHING -when oxygen concentration in blood becomes very low, oxygen sensors in aorta and carotid arteries send signals to the medulla and pons, which respond by increasing the breathing rate.

  17. Partial Pressure: portion of atmospheric pressure contributed by a certain gas *ex: at sea level, atmosphere exerts 760mmHg; atmosphere is 21% of O2 by volume, 0.21 x 760 = 160 mmHg *PO2= 160 mmHg *PCO2 = 0.23 mmHg *diffusion of gas depends on a difference of partial pressure  gases move from higher to lower partial pressure

  18. RESPIRATORY PIGMENTS • Resp. pigment of of almost all vertebrates is hemoglobin (Hb) • Consists of 4 protein subunits (tertiary structures) • Each Hb can carry 4 oxygen molecules • Hb binds oxygen reversibly; depends upon PO2 gradient

  19. Hb also helps transport CO2 & assists in preventing harmful changes in blood pH • H+ affect the conformation of Hb • Drop in pH shifts the dissociation curve to the right & more O2 is released Bohr Shift

  20. Asthma: inflammation in the airways. When an asthma attack occurs, the muscles surrounding the airways become tight and the lining of the air passages swells; can also fill with mucus • Emphysema: destruction of lung tissue around alveoli, makes these air sacs unable to hold their functional shape upon exhalation. Disorders and Diseases of the Respiratory System:

  21. Disorders and Diseases of the Respiratory System: • Cancer: uncontrolled cell division • Cystic fibrosis: autosomal disorder; causes thick, sticky mucus to build up in the lungs, digestive tract, and other areas of the body

  22. Disorders and Diseases of the Respiratory System: • Tuberculosis (TB) • contagious bacterial infection that involves the lungs, but may spread to other organs • Pneumonia • inflammation of the lungs caused by infection. Bacteria, viruses, fungi or parasites can cause pneumonia.

  23. Disorders and Diseases of the Respiratory System: • Common cold: upper respiratory system infection caused by adenovirus • Flu: respiratory system infection caused by influenza virus; symptoms are more severe than for a cold

  24. Disorders and Diseases of the Respiratory System: • Whooping cough (pertussis): • highly contagious bacterial disease that causes uncontrollable, violent coughing which can make it hard to breathe • Plague: • Caused by bacteria & people are infected when they are bitten by fleas on infected rodents

  25. Disorders and Diseases of the Respiratory System: • Anthrax: • infectious disease due to a type of bacteria called Bacillus anthracis. Infection in humans most often involves the skin, gastrointestinal tract, or lungs

  26. Disorders and Diseases of the Respiratory System: • Strep throat: • infection with a germ called Group A Streptococcus bacteria

  27. Disorders and Diseases of the Respiratory System: • Bronchitis: • mucus membrane in the lungs' bronchial passages becomes inflamed.  • As the irritated membrane swells and grows thicker, it narrows or shuts off the tiny airways in the lungs, resulting in coughing spells that may be accompanied by phlegm and breathlessness.

  28. Disorders and Diseases of the Respiratory System: • Laryngitis: • inflammation of your voice box (larynx) from overuse, irritation or infection Normal vocal chords Inflamed vocal chords

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