Mechanics of Breathing 17

About this Chapter The respiratory system Gas laws Ventilation

Respiratory System Exchange of gases between the atmosphere and the blood Homeostatic regulation of body pH Protection from inhaled pathogens and irritating substances Vocalization

Principles of Bulk Flow Flow from regions of higher to lower pressure Muscular pump creates pressure gradients Resistance to flow Diameter of tubes

Respiratory System Overview of external and cellular respiration Figure 17-1

Respiratory System Conducting system Alveoli Bones and muscle of thorax

Respiratory System Figure 17-2a

Muscles Used for Ventilation Figure 17-2b

The Respiratory System The relationship between the pleural sac and the lung Figure 17-3

Branching of Airways Figure 17-2e

Branching of the Airways Figure 17-4

Alveolar Structure Figure 17-2g

Pulmonary Circulation Right ventricle  pulmonary trunk  lungs  pulmonary veins  left atrium PLAY Animation: Respiratory System: Anatomy Review

Gas Laws

Gas Laws Pgas = Patm  % of gas in atmosphere

Boyle’s Law Gases move from areas of high pressure to areas of low pressure Figure 17-5

Spirometer Figure 17-6

Lungs Volumes and Capacities Figure 17-7

Conditioning Warming air to body temperature Adding water vapor Filtering out foreign material

Ciliated Respiratory Epithelium Figure 17-8

Air Flow Flow  P/R Alveolar pressure or intrapleural pressure can be measured Single respiratory cycle consists of inspiration followed by expiration

Movement of the Diaphragm Figure 17-9a

Movement of the Diaphragm Figure 17-9b

Movement of the Diaphragm Figure 17-9c

Movement of the Rib Cage during Inspiration Figure 17-10a

Movement of the Rib Cage during Inspiration Figure 17-10b

Pressure Changes during Quiet Breathing Figure 17-11

Pressure in the Pleural Cavity Figure 17-12a

Pressure in the Pleural Cavity Pneumothorax results in collapsed lung that can not function normally Figure 17-12b

Compliance and Elastance Compliance: ability to stretch High compliance Stretches easily Low compliance Requires more force Restrictive lung diseases Fibrotic lung diseases and inadequate surfactant production Elastance: returning to its resting volume when stretching force is released

Law of LaPlace Surface tension is created by the thin fluid layer between alveolar cells and the air Figure 17-13

Surfactant More concentrated in smaller alveoli Mixture containing proteins and phospholipids Newborn respiratory distress syndrome Premature babies Inadequate surfactant concentrations

Air Flow PLAY Animation: Respiratory System: Pulmonary Ventilation

Ventilation Total pulmonary ventilation and alveolar ventilation Total pulmonary ventilation = ventilation rate  tidal volume 150 mL 350 2700 mL 2200 mL Dead space filled with fresh air PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Respiratory cycle in an adult End of inspiration Inhale 500 mL of fresh air (tidal volume). Dead space filled with stale air KEY Only 350 mL reaches alveoli. The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. Dead space is filled with fresh air. The first 150 mL of air into the alveoli is stale air from the dead space. At the end of expiration, the dead space is filled with “stale” air from 500 mL Atmospheric air Exhale 500 mL 1 2 3 4 Figure 17-14

Ventilation Figure 17-14, step 1 Dead space filled with fresh air 150 mL 2700 mL Dead space filled with fresh air PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Respiratory cycle in an adult KEY 1 End of inspiration Figure 17-14, step 1

Ventilation Figure 17-14, steps 1–2 Dead space filled with fresh air 150 mL 2700 mL 2200 mL Dead space filled with fresh air PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Respiratory cycle in an adult End of inspiration KEY The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. 350 Exhale 500 mL (tidal volume). 1 2 Figure 17-14, steps 1–2

Ventilation Figure 17-14, steps 1–3 150 mL 2700 mL 2200 mL Dead space filled with fresh air PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Respiratory cycle in an adult End of inspiration Dead space filled with stale air KEY The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. At the end of expiration, the dead space is filled with “stale” air from alveoli. 350 Exhale 500 mL (tidal volume). 1 2 3 Figure 17-14, steps 1–3

Ventilation Figure 17-14, steps 1–4 150 mL 350 2700 mL 2200 mL Dead space filled with fresh air PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Respiratory cycle in an adult End of inspiration Inhale 500 mL of fresh air (tidal volume). Dead space filled with stale air KEY Only 350 mL reaches alveoli. The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. Dead space is filled with fresh air. The first 150 mL of air into the alveoli is stale air from the dead space. At the end of expiration, the dead space is filled with “stale” air from 500 mL Atmospheric air Exhale 500 mL 1 2 3 4 Figure 17-14, steps 1–4

Ventilation Figure 17-14, steps 1–5 150 mL 350 2700 mL 2200 mL Dead space filled with fresh air PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Respiratory cycle in an adult End of inspiration Inhale 500 mL of fresh air (tidal volume). Dead space filled with stale air KEY Only 350 mL reaches alveoli. The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. Dead space is filled with fresh air. The first 150 mL of air into the alveoli is stale air from the dead space. At the end of expiration, the dead space is filled with “stale” air from 500 mL Atmospheric air Exhale 500 mL 1 2 3 4 Figure 17-14, steps 1–5

Ventilation Alveolar ventilation = ventilation rate  (tidal volume – dead space volume)

Ventilation

Ventilation

Ventilation Effects of changing alveolar ventilation on PO2 and PCO2 in the alveoli Figure 17-15

Ventilation

Ventilation Local control matches ventilation and perfusion Figure 17-16a

Ventilation Figure 17-16b

Ventilation Figure 17-16c

Ventilation Auscultation = diagnostic technique Obstructive lung diseases Asthma Emphysema Chronic bronchitis

Summary Respiratory system Gas Laws: Dalton’s law and Boyle’s law Cellular respiration, external respiration, respiratory system, upper respiratory tract, pharynx, and larynx Lower respiratory tract, trachea, bronchi, bronchioles, alveoli, Type I and Type II alveolar cells Diaphragm, intercostal muscles, lung, pleural sac, and plural fluid Gas Laws: Dalton’s law and Boyle’s law

Summary Ventilation Tidal volume, vital capacity, residual volume, and respiratory cycle Alveolar pressure, active expiration, intrapleural pressures, compliance, elastance, surfactant, bronchoconstriction, and bronchodilation Total pulmonary ventilation, alveolar ventilation, hyperventilation, and hypoventilation