1 / 46

Respiratory System

Respiratory System. Dr. Anderson GCIT. Basic Concepts. Surface area relative to diffusion Physics of Airflow Special ways to insure against pathogen invasion of large mucus membranes (lungs and sinuses). Nose and Sinuses. Nose Functions. Opening for air exchange Moistens and warms air

fionn
Download Presentation

Respiratory System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Respiratory System Dr. Anderson GCIT

  2. Basic Concepts • Surface area relative to diffusion • Physics of Airflow • Special ways to insure against pathogen invasion of large mucus membranes (lungs and sinuses)

  3. Nose and Sinuses

  4. Nose Functions • Opening for air exchange • Moistens and warms air • Houses sensory (smell) neurons • Filters air going to lungs • Serves as resonating chamber for speech

  5. Mucus Membranes • Line the interior surfaces of the nasal cavity • Mucus and defensive compounds (enzymes) are secreted to destroy trapped pathogens (E.g. defensins) • Ciliated epithelia move mucus and trapped contaminants to the back of the throat where they are swallowed and digested in the stomach

  6. Nasal Conchae • Occur laterally from the lateral walls of the nasal cavity • Covered in mucosa and highly vascular • This serves to warm and moisten air and trap particles that may be inhaled

  7. The Pharynx • Connects nasal cavity and mouth • Nasopharynx – (Superior to level of the soft palate) - only serves to transport air • Oropharynx – (Posterior to oral cavity) – both swallowed food and air pass through • Laryngopharynx – (merging of esophagus and trachea) serves to separate food and air

  8. Larynx - Function • Provides a “switching” mechanism between inspiration and swallowing • Also houses vocal cords for speech

  9. Larynx Cartilagenous “box” that maintains an open airway • Needs to be rigid – why? • Epiglottis – fold of cartilage that closes the trachea during swallowing

  10. Voice Production • Vocal cords are stretched on either side of the larynx, and vibrate as air passed over them from the lungs • Air moves between these vocal cords through a space called the glottis • Laryngeal muscles that surround the cartilage change the pitch of the voice by flexing and relaxing

  11. Trachea (Windpipe) • Passageway for air into the lungs, from the pharynx • Rings of cartilage prevent collapse under the negative pressure of inhalation (rigid, but flexible) • Trachealis muscle allow the trachea to flex during inhalation, exhalation, sneezing and swallowing • Lined with mucosa and cilia which propels particles towards the throat to be swallowed

  12. Bronchi • Point at which the trachea bifurcates (right bronchus is wider, shorter and more vertical) • No cartilaginous rings, but irregular plates hold bronchi open • Very little mucus produced, therefore pathogens and contaminants removes by WBCs (macrophages)

  13. Bronchi • Bifurcates from trachea into lungs • Further subdivides into secondary, (tertiary, etc. bronchi) within the lungs • Bronchioles are 0.1 mm in diameter • Terminal bronchioles are 0.05 mm in diameter and lead to the alveoli

  14. Anatomy - Lungs • Left lung – divided into 2 lobes (superior and inferior) • Also has space made to accommodate the heart (cardiac notch) • Right Lung – 3 lobes (superior, middle and inferior) • Both lungs have sections called bronchopulmonary segments that are separated by connective tissue

  15. Basic Anatomy

  16. Alveoli (the respiratory zone) • Respiratory bronchioles lead to alveolar ducts which lead to alveolar sacs that make up the alveoli • Roughly 300 million alveoli present for gas exchange

  17. Blood Supply

  18. Alveoli - Structure • Composed of extremely thin single layer of squamous epithelial cells, which allows rapid diffusion of O2 in and CO2 out of the blood • Also allows the evaporation of water out of the blood

  19. Alveolar Blood Supply

  20. Mechanics of Breathing • Partial Pressure • Diffusion

  21. Atmospheric Pressure • At sea level, air rushes towards areas of relatively lower pressure and away from areas of relatively higher pressure • This difference in partial pressures changes in the chest cavity via muscle flexing and resultant forces in the thoracic cavity

  22. Diaphragm • Sheet of muscle that separates the thoracic and abdominal cavities • Flexing the diaphragm causes it to drop (inferiorly), increasing the empty volume of the thoracic cavity • The resulting negative pressure causes air to rush into the lungs and fill the negative space (inspiration) • As the diaphragm relaxes, it rises and increases the pressure in the thoracic cavity, causing exhalation

  23. Intercostal Muscles • Contraction of intercostal muscles lifts the rib cage up (superiorly) • This flexion serves to “open up” the rib cage and decreases the pressure inside the chest, causing air to rush in

  24. Physics of Airflow • Flow = Change in pressure/resistance • Look familiar? • Air is a fluid, just as blood is, and is therefore subject to the same physical rules

  25. Shouldn’t lungs collapse? • Elastic nature of lungs causes them to contract inwards • Surface tension in alveoli (water tension) tries to collapse alveoli • Wouldn’t this be bad? • How is this avoided?

  26. Pressure Balances • The outside of the lung (visceral pleura) is attached via pleural fluid to the parietal pleura (inside surface of the pleural cavity) keeping them from collapsing • This keeps the lungs clinging tightly to the thoracic wall (parietal pleura), preventing their collapse

  27. Alveolar Surfactant • Surfactant decreases the tension between water molecules (breaks the cohesiveness between molecules) • Reduces the force trying to pull individual alveoli together

  28. Respiratory Volume and Pulmonary Function • Volumes • Tidal Volume: Amount of air moved in and out under normal resting conditions • Inspiratory Reserve Volume: amount of air that can be inspired forcibly beyond the tidal volume • Expiratory Reserve Volume: volume that can be forcibly expired beyond the tidal volume • Residual Volume: air left in lungs, even after forced expiration

  29. Gas Physics • Dalton’s Law of Partial Pressures – gases exert a pressure in proportion to its concentration in a mixture • Air • 78% N2, • 21% O2, • 1% Other gases (CO2, rare gases, etc.) • Pressure of gas is proportional to its concentration in a mixture

  30. Henry’s Law • Gas will dissolve into a liquid at a rate proportional to its partial pressure and vice-versa • Gas liquid • Liquid gas • This is what allows for the movement of O2 in, and CO2 out of the blood

  31. Factors Effecting Gas Exchange Rate • Pressure Gradients (vary with altitude, etc.) • Ventilation-Perfusion coupling – must be an efficient match between the volume of air reaching the alveoli and the blood flow in pulmonary capillaries • This is accomplished via vasoconstriction/dilation • Thickness and Surface area of Respiratory Membrane • Thickening of this membrane can lead to respiration issues

  32. Oxygen Transport • O2 primarily carried by hemoglobin in blood • 4 Heme groups in hemoglobin DeoxyhemoglobinOxyhemoglobin 0 1 2 3 4 (Number of heme groups carrying Oxygen)

  33. Factors Affecting Hemoglobin Saturation • Partial Pressure of O2 • Blood pH • Temperature • BPG concentration – a metabolite that bonds reversibly with hemoglobin

  34. Bohr Effect • Increasing acidity (from increasing levels of CO2) weaken the bond between hemoglobin and O2. • What does this mean? Is this a good or bad thing?

  35. CO2 Transport • CO2 is transported in • Plasma (7-10%) • *Bound to hemoglobin (carbaminohemoglobin) – binds to amino acids, not the heme molecule • *as bicarbonate in plasma (via carbonic anhydrase) and RBC’s (enzyme-mediated in BRC cytoplasm) • CO2 loading enhances O2 release (Bohr Effect)

  36. Control of Respiration • Neural Control • Medulla Oblongata • Ventral Respiratory Group (VRG) • Phrenic and intercostal nerves cause diaphragm and intercostal contraction • Dorsal Respiratory Group (DRG) • Modulate rhythms generates by VRG due to peripheral stimulation (stretch and chemoreceptors) • Pontine Respiratory Group (PRG) • Also modulates breathing rhythm by directing impulses to the VRG • Communication between all of these centers regulates breathing rhythm

  37. Factors Influencing Breathing Rate • Chemoreceptors – monitor blood pH and O2 levels • Central (found in brain stem), monitors blood pH • Peripheral (found in aortic arch and carotid arteries), monitors CO2, blood pH • CO2 in blood (Hypercapnia) = blood pH = increased respiration rate • CO2 in blood (Hypocapnia) = blood pH = decreased respiration rate

  38. Higher Brain Respiratory Inputs • Hypothalamus • Processes sensory input (rapid chillingand/or heating, pain, etc.) or limbic input affect breathing rate • Cortical Controls • Respiration rate can be consciously controlled, but will be overridden by brain stem when CO2 gets too high

  39. Reflexive Respiration • Irritants can cause reflexive constriction of passageways • Inflation reflex – stretch receptors prevent lung over-inflation (inspiring too much air)

  40. Respiratory Adjustments • Exercise - CO2in blood (Hypercapnia) from muscle contractions • However, these are not the stimuli! • Psychological, cortical, and proprioreceptor input are the cause (we think) • Altitude • Decrease O2 pressure results in lower O2 absorption rates • Altitude Sickness – headache, nausea, fainting, death?

  41. Respiratory Diseases • COPD – Chronic Obstructive Pulmonary Diseases – irreversible decrease in the ability to force air out of the lungs • Most patients smoke (80%) • Labored breathing (dyspnea) • Coughing and infections • Hypoventilation

  42. COPD’s • Emphysema – alveoli are enlarged and walls of alveoli are destroyed • Harder to move air • Bronchioles open during inspiration, but collapse upon expiration, trapping air in the lungs • Increases resistance to blood flow causing right side of heart to increase in size • Chronic Bronchitis – constant exposure to irritants creates stagnant mucus in lungs • Decreases air flow • Increases chance of infection

  43. Other Respiration Disorders • Asthma – inflammation of lung issue increases resistance to air movement • Allergies • Stress • Due to an “aseptic environment”?? • Tuberculosis – chronic bacterial infection of the lungs • Lung Cancer • Very often metastasizes before detection

More Related