Respiratory Physiology

Respiration: General Purpose- To stay alive Speech is an overlaid function Respiratory patterns different for: –Breathing for life –Breathing for speech

Relationship of Lung, Thorax & Abdomen Motion of rib cage & diaphragm cause volume change (inc. & dec) Surface of lungs linked to surface of thoracic walls & diaphragm –Linkage- Fluid interface between pleura Visceral Pleurae- lines lung Parietal Pleurae- lines thoracic cavity Pleural cavity- space between visceral & parietal linings Thoracic & diaphragm movement cause LV inc. & dec. –Inhalation: Lung volume and pressure

Pleural Linkage Function of surface tension of the fluid in pleural space –e.g.. Wet sheets of glass (resist separation but free to move) Only surface tension accounting for pleural linkage? No, linkage a function of: –Fluid transport out of pleural space –Elasticity of pleura itself

Linkage: Diaphragm & Rib Cage Diaphragm attaches to inferior rib cage –rib cage expands = increase in diaphragm circumference –contraction of diaphragm elevates lower rib cage (Superior fibers & costal attachment) –Rib cage & diaphragm not independent

Linkage: Diaphragm & Abdomen Linked via interposed abdominal viscera –abdominal cavity bound by 2 moveable walls Diaphragm above Muscular abdominal walls anterior and lateral Lowering diaphragm increases abdominal pressure –Drives abdominal wall out

Intrapleural Pressure Larynx Trachea Lungs Visceral Pleura Parietal Pleura Alveolar Pressure Intrapleural Pressure (cm H 2 O) Volume (Liters) Lung Volume Time (Seconds) Insp Exp

Respiratory Volumes Total Capacity Vital Capacity Residual Volume Inspiratory Volume Reserve Tidal Volume Expiratory Volume Reserve Residual Volume Percent Vital Capacity

Residual volume (RV)= Quantity of air remaining in the lungs after as much air as possible has been expelled from the lungs (25% of TLC) Total Lung Capacity (TLV)= The sum of inspiratory reserve volume, tidal volume, expiratory & inspiratory reserve volume and residual volume (TLC=IC + FRC). Vital Capacity (VC)= The maximum volume of air that can be exchanged during respiration is the difference between TLC and RV. Tidal Volume (TV)= Volume of air exchanged in one cycle of respiration (one breath). Inspiratory & Expiratory Reserve Volume (IRV) & (ERV): Part of VC still available at the end of a given inhalation or exhalation respectively. Functional Residual Capacity (FRC): The volume of air in the body at the end of passive exhalation, including expiratory reserve & residual volumes (FRC=ERV+RV)

Total Lung Capacity Tidal Volume Inspiratory Capacity Vital Capacity Expiratory Reserve Volume Inspiratory Reserve Volume Tidal Volume (Increasing Activity) Residual Volume Resting Expiratory Level Functional Residual Capacity Spirometer for measuring respiratory volume

Measurement of Respiration Respiratory flow, volumes & capacities are measured using a spirometer Amount of water displaced gives you estimate of the air required to displaces it Air Chamber Water Recording Drum

Measurement of Respiration cm H 2 O Manometer -Measures Pressure; more force used the higher the water rises

Respiration for Life Quiet respiration & Forced respiration –Economy of effort –Minimum departure from the resting volume –Relaxed balance exists between tendencies of thorax expansion & lung collapse –Balance is typically at 35-40% of vital capacity (amount available for use) –Quiet inspiration= the volume of air that can be inhaled from a resting level with muscle contraction –Quiet expiration= Passive process by elastic recoil of lungs & abdomen

Quiet Respiration 40% Insp. 60% Exp. Resting Tidal Volume Resting Volume 0 40 Percent of Vital Capacity *Volume of air move called resting tidal volume *40% of cycle spent on inspiration; 60% of cycle spent on expiration

Forced Respiration Increased energy demands for air exchange in lungs –muscular support recruited for insp. & exp. –Forced insp.= ? –Forced expiration=? Go beyond resting inhalation or exhalation= recruit muscle involvement Time spent about the same as in quiet respiration

Respiration for Life Ventilation –Actual movement of air in the conducting respiratory pathway –Air distributed: 3 million alveoi; perfused (picks up oxygen) through 6 million capillaries –Diffussion takes place (actual gas exchange across alveolar-capillary membrane)

Development Developmental Changes (infancy-adulthood): –Increase in VC –VC increases fairly regularly with age –Young adult times the lung volume of a 5 year old child –VC depends on volume of lung tissue –Peak reached in late teens or 20’s –Decrease after early 20’s & reduction of diaphragmatic action –Residual volume increase with age

Vital Capacity Based on Age & Gender Male Female VC (ml) Age (Years)

Typical Respiratory Volumes & Capacities in Adults Volume/ Capacity Males (cc) Females (cc) Average (in cc) VC 4800 cc 3200 cc 4000 cc TLC 6000 cc 4800 cc 5100 cc Resting TV 600 cc 450cc 525cc Males: VC in ml= (0.112 x age in years) x ht.in cm Females: VC in ml= (0.101 x age in years) x ht.in cm

Breathing for Speech Same respiratory equipment and measures of air volume &lung capacity apply for speech breathing Difference? How & Why they are used! –Life- Objective to move O 2 & CO 2 in & out of lungs resistance interferes –Speech- Objective to have air under pressure; force vocal folds to vibrate Achieve pressure by resisting airflow

Respiratory Pressures Alveolar Pressure Intrapleural Pressure Subglottal Pressure Intraoral Pressure Atmospheric Pressure

Respiratory Pressures Atmospheric Intraoral Subglottal Intrapleural

Respiratory Pressures Atmospheric (P atm ): Exerts pressure on earth’s surface; our reference with which to compare resp. pressures (zero) Intraoral (P m ): Pressure within the mouth Subglottal (P s ): Pressure below the vocal folds Intrapleural (P pl ): Pressure in the space between the parietal and visceral pleura

Reading Readings: –Seikel: Ch. 4, (Pgs ) –Maue-Dickson: Ch.3 (Pgs )