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Respiratory System

Respiratory System. Cellular Respiration. Most cells utilize cellular respiration to convert the chemical energy stored in nutrient macromolecules to the chemical energy utilized by cells  ATP

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Respiratory System

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  1. Respiratory System

  2. Cellular Respiration • Most cells utilize cellular respiration to convert the chemical energy stored in nutrient macromolecules to the chemical energy utilized by cells  ATP • This process is an oxidation reaction  a steady supply of oxygen is required to combust glucose to carbon dioxide and water

  3. Cellular Respiration

  4. Cellular Respiration • Respiratory systems support cellular respiration by facilitating gas exchange of oxygen and carbon dioxide between the organism and the environment

  5. Evolution of Respiratory Systems • Simple Diffusion – gases are exchanged across the moist exterior surface of the organism’s body e.g. single cell organisms; sponges; cnidaria; and worms • Gills – large surface areas that are richly supplied with blood capillaries are in close contact with water containing dissolved gases e.g. some mollusks and crustacea; and fish

  6. Evolution of Respiratory Systems • Book Lungs – a series of moist, page-like membranes within a chamber of the organism that facilitate gas exchange e.g. spiders and scorpions • Tracheae – system of highly branched tubes that extend from the exterior surface of the organism to every cell in its’ body e.g. insects

  7. Book Lungs

  8. Evolution of Respiratory Systems • Lungs – chambers containing moist, delicate respiratory surfaces that are protected within the body e.g. amphibia through to mammals

  9. Human Respiratory System Four distinct stages in respiration: • Breathing – entrance and exit of air into and out of lungs • External respiration – gas exchange between air and blood • Internal respiration – gas exchange between blood and body cells • Cellular respiration – in body cells

  10. Human Respiratory System • The human respiratory system consists of two distinct parts: • Conducting portion – a series of passageways that carry air by bulk flow into the gas exchange portion • Gas exchange portion – membraneous sacs where gases are exchanged between air in sacs and blood in capillaries

  11. Conducting Portion Purpose – to carry air to the respiratory membranes in the lungs • Nose Nasal cavity Pharynx, or Mouth Oral cavity Pharynx (common chamber) • Pharynx Larynx (contain vocal cords) • Larynx Trachea (rings of cartilage) • Trachea Left or Right Bronchus • Bronchus Bronchioles • Bronchioles Alveoli (singular : alveolus)

  12. The Lungs • Paired, cone shaped organs that lie on either side of the heart in the thoracic cavity • Right lung has 3 lobes, the left lung has 2 lobes (allowing room for the heart) • Bronchus, bronchioles and alveoli are contained in each lung

  13. Conducting Portion • As air travels through the conducting portion, it is: • Warmed • Moistened • Filtered by mucus and cilia (tiny hairs) that line the conducting portion

  14. Gas Exchange Portion - Alveolus • Each lung contains approximately 300 million alveoli • Individual alveoli are tiny – 0.2 mm diameter – but collectively the alveoli provide 70 square meters of surface area for gas exchange • This surface area is the size of a tennis court, and is 40x the surface area of your skin

  15. Alveolus • The alveoli cluster together at the end of a bronchiole like a cluster of grapes • The cluster of alveoli are surrounded by an intricate network of blood capillaries • Because the alveolus is only one cell layer thick, and the blood capillary is one cell layer thick, gases are able to move by diffusion between our blood and the air we breathe in • This diffusion of gases is facilitated by a thin layer of water that coats the interior surface of each alveolus

  16. Gas Exchange: External Respiration • High CO2/ low O2 blood is pumped from the right ventricle of the heart, through the pulmonary arteries, to the capillaries that surround each alveolus • The air in the alveoli is high in oxygen, so oxygen moves by diffusion into the blood of the alveolar capillaries • The blood in the lung capillaries is high in carbon dioxide, so carbon dioxide moves by diffusion into the alveoli sacs • High O2/ low CO2 blood leaves the alveolar capillaries, through the pulmonary vein, to the left atrium of the heart

  17. Gas Exchange: Internal Respiration • The left ventricle pumps high O2/ low CO2 blood along the aorta and arteries to the capillaries that are in contact with individual cells • The blood in the body capillaries has more oxygen than the body cells, so oxygen diffuses from the blood into the body cells • The body cells have more carbon dioxide than the blood, so carbon dioxide diffuses from the body cells into the blood in the body capillaries • High CO2/ low O2 blood leaves the body capillaries, travels through veins and the vena cava to the right atrium

  18. Oxygen <5% of oxygen travels in blood as a dissolved gas >95% of oxygen travels in blood attached to hemoglobin (oxyhemoglobin) Carbon Dioxide 10% of carbon dioxide travels in blood as dissolved gas 20% of carbon dioxide travels in blood attached to hemoglobin (carbaminohemoglobin) 70% of carbon dioxide reacts with water in blood plasma to form the bicarbonate ion (HCO3-) Chemistry of Gas Exchange

  19. Hemoglobin • Hemoglobin preferentially binds oxygen over carbon dioxide (but oddly, binds carbon monoxide preferentially over oxygen!) • 1 hemoglobin molecule is able to bind 4 oxygen molecules • Because of hemoglobin our blood can carry 70x more oxygen than it would as a dissolved gas in plasma

  20. Bicarbonate Ion CO2 + H20  H2CO3 (carbonic acid) H2CO3  H+ + HCO3- • This reaction is catalyzed by carbonic anhydrase embedded in the capillary walls • This reaction is reversible

  21. External Respiration • HbCO2 Hb + CO2 (g)↑ carbaminohemoglobin • H+ + HCO3- H2CO3 • H2CO3 H2O + CO2 (g)↑ 4. Hb + O2(g)↓ HbO2 deoxyhemoglobin oxyhemoglobin • HHb  Hb + H+ reduced hemoglobin

  22. HHb HbCO2 O2 Hb

  23. Internal Respiration • HbO2 Hb + O2 • Hb + CO2  HbCO2 • CO2 + H2O  H2CO3 • H2CO3  H+ + HCO3- • Hb + H+  HHb

  24. HbCO2 Hb HHb

  25. Binding Capacity of Hemoglobin • pH and temperature affect the binding capacity of hemoglobin • Cooler temperature (37 C) and higher pH (7.40) of lungs raises oxygen binding capacity of hemoglobin to 98% • Warmer temperature (38 C) and lower pH (7.38) of body cells lowers the oxygen binding capacity of hemoglobin to 60%

  26. Binding Capacity of Hemoglobin • This is important as the hemoglobin/RBC in the lung capillaries want to be able to bind as much oxygen as possible from the air in the alveoli • The hemoglobin/RBC in the body capillaries want to be able to release oxygen to the body cells and pick up carbon dioxide from the body cells

  27. Mechanics of Breathing • Breathing is the entrance and exit of into and out of the lungs • Exhalation= Expiration= air exiting the lungs • Inhalation= Inspiration= air entering the lungs • Breathing is a biomechanical process

  28. Features of Thoracic Cavity • For breathing to occur, the thoracic cavity must be air-tight: • The interior of the thoracic cavity is lined with an air-tight membrane called the parietal pleura • Each lung is surrounded with an air-tight membrane called the visceral pleura • The space between the two pleura (interpleural cavity) contains a lubricant • The muscular diaphragm seals the bottom of the thoracic cavity

  29. Thoracic Cavity

  30. Inhalation • Diaphragm contracts and drops down • Intercostal muscles in the rib cage contract and push up and out • The thoracic cavity increases in volume • Pressure in the lungs decreases • Air rushes into the lungs

  31. Inhalation

  32. Exhalation • Diaphragm relaxes and moves up • Intercostal muscles in the rib cage relax and move down and in • The thoracic cavity decreases in volume • Pressure in the lungs increases • Air rushes out of the lungs

  33. Exhalation

  34. Stimuli for Breathing: Inhalation • Primary stimuli: rising CO2 and H+ ion levels trigger the respiratory center in the medulla oblongata of the brain  nerve impulse is sent along intercostal nerve to contract intercostal muscles and along phrenic nerve to contract diaphragm

  35. Stimuli for Breathing: Inhalation • Secondary stimuli: decreasing O2 levels trigger chemoreceptors in carotid bodies of carotid arteries and aortic bodies of aorta  nerve impulse to respiratory center of medulla oblongata

  36. Stimuli for Breathing: Exhalation • Primary stimulus: as air moves into the lungs during inhalation, the alveoli sacs expand  this stimulates stretch receptors around the alveoli  initiates a nerve impulse sent to the respiratory center to turn off inhalation nerve impulse

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