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RESPIRATORY PHYSIOLOGY

RESPIRATORY PHYSIOLOGY. Anatomy and Physiology. Pulmonary Ventilation- breathing. Boyle’s Law - volume of a gas caries inversely with pressure at a constant temperature Defines the relationship between gas pressure and volume volume decrease  pressure increases

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RESPIRATORY PHYSIOLOGY

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  1. RESPIRATORY PHYSIOLOGY Anatomy and Physiology

  2. Pulmonary Ventilation- breathing • Boyle’s Law- volume of a gas caries inversely with pressure at a constant temperature Defines the relationship between gas pressure and volume • volume decrease  pressure increases • Volume increase  pressure decreases

  3. Respiration • What is respiration? • External respiration – exchange of O2 and CO2 between respiratory surfaces and the blood (breathing) • Internal respiration – exchange of O2 and CO2 between the blood and cells • Cellular respiration – process by which cells use O2 to produce ATP

  4. The Respiratory Muscles Figure 23–16c, d

  5. Inspiration • Expansion of thorax (increased volume) leads to decreased intrapleural pressure, causing air to move inside the lung

  6. 3 Muscle Groups of Inhalation • Diaphragm: • contraction draws air into lungs • 75% of normal air movement • External intracostal muscles: • assist inhalation • 25% of normal air movement • Accessory muscles assist in elevating ribs: • sternocleidomastoid • serratus anterior • pectoralis minor • scalene muscles

  7. Contraction of diaphragm • Contraction of external intercostals • Contraction of sternocleidomastoid, pectoralis minor, serratus ventralis/ant.

  8. Expiration • Inspiratory muscles relax, causing decrease in size of thorax and increase in intrapleural press., releasing air.

  9. Factors Influencing Pulmonary Ventilation • Airway resistance: friction/drag • Diameter of airways • Alveolar surface tension  shrinks alveoli • Surfactant: detergent-like film of lipids and proteins that reduces surface tension • IRDS: Infant respiratory distress syndrome • Lung compliance: ease by which the lungs can be expanded • Reduced in fibrosis • Blocking smaller pathways  pneumonia and bronchitis

  10. Pulmonary Volumes (1-4) • Tidal volume (TV)- volume of air exhaled normally after typical inspiration. ~500 ml • Expiratory Reserve Volume (ERV)- largest additional volume of air that one can forcibly expire after expiring tidal air. ~1000-1200 ml • Inspiratory Reserve Volume (ERV)- amount of air that can be forcibly inspired over and above normal inspiration ~2100-3200 ml • Residual Volume (RV)- amount of air that cannot be forcibly expired ~ 1200 ml

  11. Pulmonary Volumes 5. Vital Capacity (VC)= IRV + TV + ERV • The largest volume of air that an individual can move in and out of the lungs. • Determined by measuring the largest possible expiration after the largest possible inspiration. • In general, larger people have larger VC.

  12. Lung Volumes: Spirometry

  13. Review Lung & Breathing Volumes

  14. What’s going on here?

  15. C. Exchange of Gases in the Lungs • Gases move both ways • Oxygen enters blood from the alveolar air from an area of higher to lower concentration • Carbon dioxide move from the blood into the alveoli in the same way • This 2 way exchange converts deoxygenated blood to oxygenated blood

  16. External Respiration • Exchange of O2 and CO2 between alveoli and blood • Partial pressure of O2 higher in alveoli than blood so O2 diffuses into blood • Partial pressure of CO2 higher in blood than alveoli, so CO2 moves into alveoli in opposite direction and gets exhaled out

  17. Form meets functions

  18. Internal Respiration • Exchange of O2 and CO2 between blood and tissues • Pressure of O2 higher in blood than tissues so O2 gets release into tissues. • Pressure of CO2 higher in tissue than in blood so CO2 diffused in opposite direction into blood. • CO2 Is a waste product • O2 Is used in cellular respiration

  19. D. How Blood Transports Gases • Large volumes of gases can be transported by binding to proteins rather than dissolving in plasma • Hemoglobin in red blood cells is a quaternary protein with 2 alpha and 2 beta chains associated with iron-containing heme groups. • O2 can combine with Fe • CO2 can combine with the alpha and beta chains

  20. How Blood Transports Gases • Carbon dioxide • 70% as bicarbonate ion (HCO3-) dissolved in plasma • 23% bound to hemoglobin • 7% as CO2 dissolved in plasma • Oxygen • 99% bound to hemoglobin • 1% as O2 dissolved in plasma • Carbon monoxide poisoning occurs because CO binds to hemoglobin more readily than O2

  21. Hamburger's phenomenon  Chloride Shift

  22. E. Regulation of Breathing • Respiratory centers- in brainstem; control nerves that affect breathing muscles • medullary rhythmic center with inspiratory and expiratory centers • apneustic center in the pons • pneumontaxic center in the pons

  23. Control of Breathing Regulated by 4 factors: • changes in concentration of O2 and CO2 • increase CO2 sends message to increase breathing frequency and breath more deeply • changes in blood pH • arterial blood pressure • Cerebral cortex nervous control - natural flight response triggers increased rate of breathing

  24. Control of Breathing • Breathing is regulated by the rhythmicity center in the medulla of brain • Medulla stimulates inspiratory muscles (diaphragm & external intercostal muscles) rhytmicity center

  25. Control of Breathing • The most important factor affecting the rhythmicity center is CO2 •  in arterial CO2 causes  in acidity of cerebrospinal fluid (CSF) •  in CSF acidity is detected by pH sensors in medulla • medulla  rate and depth of breathing

  26. Why does breathing rate increase during exercise? • CO2 levels increase • Blood becomes acidic • Aorta sends signals to brain • Brain stimulates diaphragm to contract more rapidly • Therefore, you take in more O2 and release more CO2

  27. Respiratory System at Birth • Before birth: • pulmonary vessels are collapsed • lungs contain no air • During delivery: • placental connection is lost • blood PO2falls • PCO2 rises • At birth: • newborn overcomes force of surface tension to inflate bronchial tree and alveoli and take first breath

  28. Respiratory System at Birth • Large drop in pressure at first breath: • pulls blood into pulmonary circulation • closing foramen ovale and ductus arteriosus • redirecting fetal blood circulation patterns • Subsequent breaths: • fully inflate alveoli

  29. 3 Effects of Aging on the Respiratory System • Elastic tissues deteriorate: • reducing lung compliance • lowering vital capacity • Arthritic changes: • restrict chest movements • limit respiratory minute volume • Emphysema: • affects individuals over age 50 • depending on exposure to respiratory irritants (e.g., cigarette smoke)

  30. Respiratory Performance and Age Figure 23–28

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