Figure 23.17 The Respiratory Muscles Figure 23.17a-d

Thoracic Volume

Figure 23.18 Respiratory Volumes and Capacities

Gas exchage at respiratory surface

Figure 23.24 Carbon Dioxide Transport in Blood

Gas exchange at the tissue level

Figure 23.27 Respiratory Centers and Reflex Controls

Tuberculosis Mycobacterium tuberculosis

Pulmonary Ventilation The physical movement of air into and out of the lungs

Air movement Movement of air depends upon Boyle’s Law P1V1 = P2V2 Pressure and volume inverse relationship Volume depends on movement of diaphragm and ribs Pressure and airflow to the lungs Compliance – an indication of the expandability of the lungs

Figure 23.14 Respiratory Pressure and Volume Relationships Figure 23.14a, b

Pressure changes during inhalation and exhalation Relationship between intrapulmonary pressure and atmospheric pressure determines direction of air flow Intrapleural pressure maintains pull on lungs Pressure in the space between parietal and visceral pleura Intrapleural pressure is always less than atmospheric.

Figure 23.15 Mechanisms of Pulmonary Ventilation Figure 23.15a-d

Figure 23.16 Pressure Changes during Inhalation and Exhalation

Mechanisms of breathing Quiet breathing (eupnea) Diaphragm and external and internal intercostals muscles Forced breathing (hyperpnea) Accessory muscles

Respiratory volumes Alveolar volume Amount of air reaching the alveoli each minute Tidal Volume (VT) Amount of air inhaled or exhaled with each breath Vital capacity Tidal volume plus expiratory and inspiratory reserve volumes Residual volume Air left in lungs after maximum exhalation

Figure 23.20 An Overview of Respiratory Processes and Partial Pressures in Respiration PLAY Animation: Respiratory Processes and Partial Pressures in Respiration Figure 23.20a, b

Oxygen transport Carried mainly by RBCs, bound to hemoglobin The amount of oxygen hemoglobin can carry is dependent upon: PO2 pH temperature BPG Fetal hemoglobin has a higher O2 affinity than adult hemoglobin

Figure 23.21 The Oxygen-Hemoglobin Saturation Curve

Figure 23.22 The Effect of pH and Temperature on Hemoglobin Saturation Figure 23.22a, b

Figure 23.23 A Functional Comparison of Fetal and Adult Hemoglobin

Respiratory centers of the brain Medullary centers Respiratory rhythmicity centers - set pace Pons Even out-smooth out inspiration/expiration

Figure 23.28 The Chemoreceptor Response to Changes in PCO2

Gas absorption/generation balanced by capillary rates of delivery/removal Homeostatic mechanisms maintain balance Local regulation of gas transport and alveolar function include Lung perfusion Alveolar capillaries constrict in low oxygen Alveolar ventilation Bronchioles dilate in high carbon dioxide

Respiratory reflexes Respiratory centers are modified by sensory information including Chemoreceptor reflexes Level of carbon dioxide Baroreceptors reflexes Hering-Breuer reflexes Prevents overinflation Protective reflexes

Voluntary control of respiration Regulation of respiratory rate is dependent upon: Conscious and unconscious thought Emotional state Anticipation PLAY Animation: Control of Respiration

Diffusion and respiratory function Gas exchange across respiratory membrane is efficient due to: Differences in partial pressure Small diffusion distance Lipid-soluble gases Large surface area of all alveoli Coordination of blood flow and airflow