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Respiratory System

Learn about the functions of the respiratory system, its divisions, and the process of ventilation. Understand how air moves in and out of the lungs, the exchange of gases, and the various functions of the respiratory system.

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Respiratory System

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  1. Respiratory System

  2. Respiration • Ventilation: Movement of air into and out of lungs • External respiration: Gas exchange between air in lungs and blood • Transport of oxygen and carbon dioxide in the blood • Internal respiration: Gas exchange between the blood and tissues • Cellular Respiration: The use of O2 to produce ATP via Glycolysis, TCA cycle, & ETS

  3. Respiratory System Functions • Gas exchange: Oxygen enters blood and carbon dioxide leaves • Regulation of blood pH: Altered by changing blood carbon dioxide levels Carbonic acid Buffer system • Sound production: Movement of air past vocal folds makes sound and speech • Olfaction: Smell occurs when airborne molecules drawn into nasal cavity • Thermoregulation: Heating and cooling of body • Protection: Against microorganisms by preventing entry and removing them

  4. Respiratory System Divisions • Upper tract • Nose, pharynx and associated structures • Lower tract • Larynx, trachea, bronchi, lungs

  5. Nasal Cavity and Pharynx

  6. Nose External nose Nasal cavity Functions Passageway for air Cleans the air Humidifies, warms air Smell Along with paranasal sinuses are resonating chambers for speech Pharynx Common opening for digestive and respiratory systems Three regions Nasopharynx Oropharynx Laryngopharynx Nose and Pharynx

  7. Larynx • Functions • Maintain an open passageway for air movement • Epiglottis and vestibular folds prevent swallowed material from moving into larynx • Vocal folds are primary source of sound production

  8. Vocal Folds

  9. Trachea • Windpipe • Divides to form • Primary bronchi • Carina: Cough reflex Insert Fig 23.5 all but b

  10. Tracheobronchial Tree • Non-Acinus -Conducting zone • Trachea to terminal bronchioles which is ciliated for removal of debris, mucus lined • Passageway for air movement controlled by smooth muscle at end of terminal bronchioles • Cartilage holds tube system open and smooth muscle controls tube diameter • Acinus Portion - Respiratory zone • Respiratory bronchioles to alveoli • Site for gas exchange Area the size of a football field

  11. Tracheobronchial Tree

  12. Bronchioles and Alveoli

  13. Alveolus and Respiratory Membrane

  14. Lungs • Two lungs: Principal organs of respiration • Right lung: Three lobes • Left lung: Two lobes • Divisions • Lobes, bronchopulmonary segments, lobules

  15. Thoracic WallsMuscles of Respiration

  16. Thoracic Volume

  17. Pleura • Pleural fluid produced by pleural membranes • Acts as lubricant • Helps hold parietal and visceral pleural membranes together

  18. Ventilation • Movement of air into and out of lungs via negative pressure pump mechanism • Air moves from area of higher pressure outside the lung to area of lower pressure created in the thorax and lungs by diaphram • Pressure is inversely related to volume in that as pressure goes down lung volume goes up

  19. Alveolar Pressure Changes

  20. Changing Alveolar Volume • Lung recoil • Causes alveoli to collapse resulting from • Elastic recoil and surface tension : Pneumothorax • Surfactant: Reduces tendency of lungs to collapse • Pleural pressure • Negative pressure can cause alveoli to expand • Pneumothorax is an opening between pleural cavity and air that causes a loss of pleural pressure

  21. Normal Breathing Cycle

  22. Compliance • Measure of the ease with which lungs and thorax expand • The greater the compliance, the easier it is for a change in pressure to cause expansion • A lower-than-normal compliance means the lungs and thorax are harder to expand • Conditions that decrease compliance • Pulmonary fibrosis • Pulmonary edema • Respiratory distress syndrome

  23. Pulmonary Volumes • Tidal volume • Volume of air inspired or expired during a normal inspiration or expiration • Inspiratory reserve volume • Amount of air inspired forcefully after inspiration of normal tidal volume • Expiratory reserve volume • Amount of air forcefully expired after expiration of normal tidal volume • Residual volume • Volume of air remaining in respiratory passages and lungs after the most forceful expiration

  24. Pulmonary Capacities • Inspiratory capacity • Tidal volume plus inspiratory reserve volume • Functional residual capacity • Expiratory reserve volume plus the residual volume • Vital capacity • Sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume • Total lung capacity • Sum of inspiratory and expiratory reserve volumes plus the tidal volume and residual volume

  25. Spirometer and Lung Volumes/Capacities

  26. Minute and Alveolar Ventilation • Minute ventilation: Total amount of air moved into and out of respiratory system per minute • Respiratory rate or frequency: Number of breaths taken per minute • Anatomic dead space: Part of respiratory system where gas exchange does not take place • Alveolar ventilation: How much air per minute enters the parts of the respiratory system in which gas exchange takes place

  27. Physical Principles of Gas Exchange • Partial pressure • The pressure exerted by each type of gas in a mixture • Dalton’s law • Water vapor pressure • Diffusion of gases through liquids • Concentration of a gas in a liquid is determined by its partial pressure and its solubility coefficient • Henry’s law

  28. Physical Principles of Gas Exchange • Diffusion of gases through the respiratory membrane • Depends on membrane’s thickness, the diffusion coefficient of gas, surface areas of membrane, partial pressure of gases in alveoli and blood • Relationship between ventilation and pulmonary capillary flow • Increased ventilation or increased pulmonary capillary blood flow increases gas exchange • Physiologic shunt is deoxygenated blood returning from lungs

  29. Oxygen Moves from alveoli into blood. Blood is almost completely saturated with oxygen when it leaves the capillary P02 in blood decreases because of mixing with deoxygenated blood Oxygen moves from tissue capillaries into the tissues Carbon dioxide Moves from tissues into tissue capillaries Moves from pulmonary capillaries into the alveoli Oxygen and Carbon Dioxide Diffusion Gradients

  30. Changes in Partial Pressures

  31. Hemoglobin and Oxygen Transport • Oxygen is transported by hemoglobin (98.5%) and is dissolved in plasma (1.5%) • Oxygen-hemoglobin dissociation curve shows that hemoglobin is almost completely saturated when P02 is 80 mm Hg or above. At lower partial pressures, the hemoglobin releases oxygen. • A shift of the curve to the left because of an increase in pH, a decrease in carbon dioxide, or a decrease in temperature results in an increase in the ability of hemoglobin to hold oxygen

  32. Hemoglobin and Oxygen Transport • A shift of the curve to the right because of a decrease in pH, an increase in carbon dioxide, or an increase in temperature results in a decrease in the ability of hemoglobin to hold oxygen • The substance 2.3-bisphosphoglycerate increases the ability of hemoglobin to release oxygen • Fetal hemoglobin has a higher affinity for oxygen than does maternal

  33. Oxygen-HemoglobinDissociation Curve at Rest

  34. Oxygen-HemoglobinDissociation Curve during Exercise

  35. Shifting the Curve

  36. Transport of Carbon Dioxide • Carbon dioxide is transported as bicarbonate ions (70%) in combination with blood proteins (23%) and in solution with plasma (7%) • Hemoglobin that has released oxygen binds more readily to carbon dioxide than hemoglobin that has oxygen bound to it (Haldane effect) • In tissue capillaries, carbon dioxide combines with water inside RBCs to form carbonic acid which dissociates to form bicarbonate ions and hydrogen ions

  37. Transport of Carbon Dioxide • In lung capillaries, bicarbonate ions and hydrogen ions move into RBCs and chloride ions move out. Bicarbonate ions combine with hydrogen ions to form carbonic acid. The carbonic acid is converted to carbon dioxide and water. The carbon dioxide diffuses out of the RBCs. • Increased plasma carbon dioxide lowers blood pH. The respiratory system regulates blood pH by regulating plasma carbon dioxide levels

  38. Carbon Dioxide Transportand Chloride Movement

  39. Respiratory Areas in Brainstem • Medullary respiratory center • Dorsal groups stimulate the diaphragm • Ventral groups stimulate the intercostal and abdominal muscles • Pontine (pneumotaxic) respiratory group • Involved with switching between inspiration and expiration

  40. Respiratory Structures in Brainstem

  41. Rhythmic Ventilation • Starting inspiration • Medullary respiratory center neurons are continuously active • Center receives stimulation from receptors and simulation from parts of brain concerned with voluntary respiratory movements and emotion • Combined input from all sources causes action potentials to stimulate respiratory muscles • Increasing inspiration • More and more neurons are activated • Stopping inspiration • Neurons stimulating also responsible for stopping inspiration and receive input from pontine group and stretch receptors in lungs. Inhibitory neurons activated and relaxation of respiratory muscles results in expiration.

  42. Cerebral and limbic system Respiration can be voluntarily controlled and modified by emotions Chemical control Carbon dioxide is major regulator Increase or decrease in pH can stimulate chemo- sensitive area, causing a greater rate and depth of respiration Oxygen levels in blood affect respiration when a 50% or greater decrease from normal levels exists Modification of Ventilation

  43. Modifying Respiration

  44. Regulation of Blood pH and Gases

  45. Herring-Breuer Reflex • Limits the degree of inspiration and prevents overinflation of the lungs • Infants • Reflex plays a role in regulating basic rhythm of breathing and preventing overinflation of lungs • Adults • Reflex important only when tidal volume large as in exercise

  46. Ventilation in Exercise • Ventilation increases abruptly • At onset of exercise • Movement of limbs has strong influence • Learned component • Ventilation increases gradually • After immediate increase, gradual increase occurs (4-6 minutes) • Anaerobic threshold is highest level of exercise without causing significant change in blood pH • If exceeded, lactic acid produced by skeletal muscles

  47. Effects of Aging • Vital capacity and maximum minute ventilation decrease • Residual volume and dead space increase • Ability to remove mucus from respiratory passageways decreases • Gas exchange across respiratory membrane is reduced

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