Introduction. Respiration. Chapter 10. Objectives. Objectives. The Respiratory System

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Howard Fields
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1 Introduction Respiration Chapter 10 The Respiratory System Provides a means of gas exchange between the environment and the body Plays a role in the regulation of acidbase balance during exercise Objectives Explain the principle physiological function of the pulmonary system Outline the major anatomical components of the respiratory system: conductive & respiratory List major muscles involved in inspiration & expiration at rest & during exercise Describe static and dynamic lung volumes Objectives Discuss the importance of matching blood flow to alveolar ventilation in the lung Explain how gases are transported across the blood-gas interface in the lung Discuss the major transportation modes of O 2 & CO 2 in the blood 1

2 Objectives Discuss the effects of temp, & ph on the oxygen-hemoglobin dissociation curve Describe the ventilatory response to constant load, steady-state exercise Describe the ventilatory response to incremental exercise Objectives Identify the location & function of chemoreceptors and mechanoreceptors that are thought to play a role in the regulation of breathing Respiration 1. Pulmonary ventilation Process by which air is moved into the lungs 2. External respiration Exchange of gases between lungs and blood Respiration Internal respiration The exchange of gases at the cellular level Cellular respiration Utilization of oxygen by the cells to produce energy 2

zone Anatomical dead space Humidifies, warms, and filters air

3 Respiration Major Organs of the Respiratory System Fig 10.1 Conducting Zone Conducting zone Conducts air to respiratory zone Anatomical dead space Humidifies, warms, and filters air Components: Trachea Bronchial tree Bronchioles Conducting Zone 3

2 Respiratory Airways 16 generations Conducting airways Bulk flow (water hose) X-sections reduces forward velocity 7 generations

4 Respiratory Zone Conducting & Respiratory Zones Respiratory zone Exchange of gases between air and blood Components: Respiratory bronchioles Alveolar sacs Fig 10.2 Respiratory Airways 16 generations Conducting airways Bulk flow (water hose) X-sections reduces forward velocity 7 generations Transitional zone Respiratory zone Diffusion Large surface area for gas exchange Minimal diffusion distance Alveolar and capillary walls-large lipid content O 2 diffuses, not H 2 O X-sectional area ft 2 Alveolar Sites 4

Respiratory Zone Alveoli (300 million) Site of gas exchange from external respiration Extensive capillarization in alveoli walls Blood gas barrier (2 cell layers thick) Lung diffusion Concentration

5 Respiratory Zone Alveoli (300 million) Site of gas exchange from external respiration Extensive capillarization in alveoli walls Blood gas barrier (2 cell layers thick) Lung diffusion Concentration gradient Minimal distance Smoking effects Diffusion Pulmonary Ventilation Dead-space ventilation (V D ) unused ventilation Does not participate in gas exchange Anatomical dead space: conducting zone Physiological dead space: disease V D = volume of dead space Included in V T Mechanics of Breathing V = v ΔP R = airflow ΔP = pressure gradient R = resistance Copyright 2007 Lippincott Williams & Wilkins 5

Mechanics of Breathing Boyle s Law The pressure of a gas is inversely related to its volume (temperature constant) Low pressure high volume High pressure low volume Surface or sea level (1 ATA) 33

6 Mechanics of Breathing Boyle s Law The pressure of a gas is inversely related to its volume (temperature constant) Low pressure high volume High pressure low volume Surface or sea level (1 ATA) 33 fsw (2 ATA) 1/2 66 fsw (3 ATA) 1/3 Boyle s Law 165 fsw (6 ATA) 1/6 (air) Lungs Lung/chest wall Pleural cavity Serous fluid Thin membranes Pleura Suction Outward pull chest wall Inward pull lungs 6

Lungs The Mechanics of Inspiration and Expiration Parietal pleura Lines the thoracic wall Visceral pleura Covers the lungs Diaphragmatic pleura Covers diaphragm Fig 10.

7 Lungs The Mechanics of Inspiration and Expiration Parietal pleura Lines the thoracic wall Visceral pleura Covers the lungs Diaphragmatic pleura Covers diaphragm Fig 10.6 Mechanics of Breathing Inspiratory muscles (rest) 1. Diaphragm Flattens and makes thoracic cavity longer Mechanics of Breathing Inspiratory muscles (rest) 2. External intercostals- Contraction lifts ribs Increases transverse diameter Increase in thoracic size 7

8 Mechanics of Breathing Inspiratory muscles (rest) Increased thoracic size - decrease in intrathoracic pressure Intrapulmonary pressure < ambient Intrapleural pressure <intrapulmonary pr <ambient Mechanics of Breathing Air moves from high pressure to low pressure Mechanics of Breathing Expiration (rest) Diaphragm and intercostals relax (passive) Thoracic cavity returns to original size Mechanics of Breathing Intrapulmonary pressure > ambient Intrapleural still lowest Air flows outward to atmosphere 8

Mechanics of Breathing Inspiration (exercise) Accessory muscles External intercostal muscles Pectoralis minor Scalene muscles Sternocleidomastoids Action Increase volume of thorax Mechanics of

9 Mechanics of Breathing Inspiration (exercise) Accessory muscles External intercostal muscles Pectoralis minor Scalene muscles Sternocleidomastoids Action Increase volume of thorax Mechanics of Breathing Expiration (exercise) Expiratory muscles Abdominal group Internal intercostals Action Lower ribs, moves them closer together Facilitates expiration (active) Muscles of Respiration Airflow Resistance Resistance to airflow Largely determined by airway diameter Asthma Shortness of breath-dyspnea Bronchospasm with exercise Increases work of breathing Exercise-induced is reversible Fig

10 Airflow Resistance Chronic obstructive pulmonary disease- COPD Constant narrowing of airways Chronic bronchitis-mucus Emphysema-decreased elastic support Airway collapse Respiratory Circulation Pulmonary circulation For external respiration Bronchial circulation For lung tissue respiration Pulmonary Circulation Pulmonary artery leaves right ventricle Separates down to capillaries alveoli Pulmonary vein leaves lungs to left atrium Low pressure system Bronchial Circulation Systemic arteries from aorta Thoracic artery Pulmonary venous system 10

11 Pulmonary Ventilation (V E ) The amount of air moved in or out of the lungs per minute Product of tidal volume (V T ) and breathing frequency (f) V E = V T x f Pulmonary Ventilation (V E ) Rest Tidal volume (V T or TV) The volume of gas moved per breath Normal resting is about 0.5 L/br or 500 ml/br Frequency of breathing (f or RR) The number of breaths per minute Normal resting is 12 to 15 Pulmonary Ventilation V E = V T x f Rest V T = 500 ml/breath f = 12 breaths/min 500 ml/breath x 12 breaths/min = 6,000 ml/min V E = 6.0 L/min Pulmonary Ventilation (V E ) Maximal Exercise (70 kg man) Tidal volume (V T or TV) The volume of gas moved per breath is about 3.0 to 3.5 L/br Frequency of breathing (f or RR) The number of breaths per minute is about 40 to 50 br/min 11

12 Pulmonary Ventilation V E = V T x f Exercise V T = 3 L/breath f = 40 br/min 3.0 L/breath x 40 breaths/min V E = 120 L/min Pulmonary Ventilation (V A ) Alveolar ventilation (V A ) Volume of inspired gas that reaches the respiratory zone (gas exchange ) V A = (V T V D ) x f V T = 500 ml, V D = 150 ml (500 ml 150 ml) = 350 ml/br f = 12 br/min V A = 350 ml/br x 12 br/min = 4.2 L/min Pulmonary Ventilation (V E ) V E = V T x f V T = 500 ml/breath f = 12 br/min V E = 500 ml/br x 12 br/min V E = 6000 ml/min V E = 6.0 L/min Pulmonary Ventilation (V A ) V A = (V T V D ) V A = (500 ml 150 ml) = 350 ml V A = 350 ml/breath x 12 breaths/min V A = 4200 ml/min V A = 4.2 L/min 12

Pulmonary Volumes and Capacities Measured by spirometry Vital capacity (VC) Maximum amount of air that can be expired following a maximum inspiration Residual volume (RV) Air remaining in the lungs

13 Pulmonary Volumes and Capacities Measured by spirometry Vital capacity (VC) Maximum amount of air that can be expired following a maximum inspiration Residual volume (RV) Air remaining in the lungs after a maximum expiration Total lung capacity (TLC) Sum of VC and RV Pulmonary Volumes and Capacities Tidal Volume Volume of air inspired or expired per breath Inspiratory Reserve Volume (IRV) Volume of air that can be inspired after a normal inspiration Expiratory Reserve Volume (ERV) Volume of air that can be expired after a normal expiration Pulmonary Volumes and Capacities Inspiratory Capacity (IC) Volume of air inspired from rest to maximal inspiration TV + IRV Functional Residual Capacity (FRC) Volume of air in lungs at rest ERV + RV Pulmonary Volumes and Capacities Fig

14 Lung Volumes: Exercise 14

Respiratory system & exercise. Dr. Rehab F Gwada

Respiratory system & exercise. Dr. Rehab F Gwada Respiratory system & exercise Dr. Rehab F Gwada Objectives of lecture Outline the major anatomical components & important functions of the respiratory system. Describe the mechanics of ventilation. List