d- chapter 19 lecture powerpoint respiratory system anatomy and physiology
TRANSCRIPT
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19.1: Introduction• The respiratory system consists of passages that filter incoming air and transport it into the body, into the lungs, and to the many microscopic air sacs where gases are exchanged• Respiration is the process of exchanging gases between the atmosphere and body cells• It consists of the following events:
• Ventilation• External respiration• Transport of gases• Internal respiration• Cellular respiration
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19.2: Why We Breathe• Respiration occurs on a macroscopic level at the organ system• Gas exchange, oxygen and carbon dioxide, occur at the cellular and molecular levels• Aerobic reactions of cellular respiration allow for:
• ATP production• Carbon dioxide generation forming carbonic acid
19.3: Organs of the Respiratory System
• The organs of the respiratory system can be divided into two tracts:
• Upper respiratory tract• The nose• Nasal cavity• Sinuses• Pharynx
• Lower respiratory tract• Larynx• Trachea• Bronchial tree• Lungs
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Larynx
Bronchus
Nostril
Right lung Left lung
Soft palate
Pharynx
Epiglottis
Esophagus
Frontalsinus
NasalcavityHardpalate
Oralcavity
Trachea
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Nose
Frontal sinus
Nostril
Hard palate
Uvula
EpiglottisHyoid bone
Larynx
SuperiorMiddleInferior
Sphenoidal sinus
Pharyngeal tonsil
Nasopharynx
Palatine tonsilOropharynx
Lingual tonsil
Laryngopharynx
Esophagus
Tongue
Trachea
Nasalconchae
Opening of auditory tube
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Nasal Cavity
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Mucus Particle
Goblet cell
CiliaNasal cavity
Epithelial cell
(b)(a)b: © Biophoto Associates/Photo Researchers, Inc.
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Sinuses• The sinuses are air-filled spaces in the maxillary, frontal, ethmoid, and sphenoid bones of the skull
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Pharynx• The pharynx is posterior to the oral cavity and between the nasal cavity and the larynx
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Frontal sinus
Nostril
Hard palate
Uvula
EpiglottisHyoid bone
Larynx
SuperiorMiddle
Inferior
Sphenoidal sinus
Pharyngeal tonsil
Nasopharynx
Palatine tonsilOropharynxLingual tonsil
Laryngopharynx
Esophagus
Tongue
Trachea
Nasalconchae
Opening ofauditory tube
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Larynx• The larynx is an enlargement in the airway superior to the trachea and inferior to the pharynx• It is composed of a framework of muscles and cartilages bound by elastic tissue
Epiglottic cartilageHyoid bone
Thyroid cartilage
Cricoid cartilage
Hyoid bone
Epiglottic cartilage
Thyroid cartilage
Cricoid cartilage
(b)
(a)
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Trachea
Trachea
False vocal cord
Glottis
Epiglottis
Hyoid bone
Thyroid cartilage
Cricoid cartilage
Hyoid bone
Epiglottis
Thyroid cartilageCricoid cartilage
(b)
(a)
False vocal cord
True vocalcord
Thyroid cartilageCuneiform cartilage
Corniculate cartilageArytenoid cartilage
True vocal cord
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Glottis
Corniculate cartilage
(a)
(b)
Epiglottis
Glottis
(c)
Posterior portionof tongue False vocal cord
True vocal cordCuneiform cartilage
Inner lining of trachea
c: © CNRI/PhotoTake
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Trachea
• The trachea (windpipe) is a flexible cylindrical tube about 2.5 centimeters in diameter and 12.5 centimeters in length• As it extends downward anterior to the esophagus and into the thoracic cavity, it splits into the right and left primary bronchi
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Larynx
Carina
Trachea
Superior (upper)lobe bronchus
Right primarybronchus
Middle lobebronchus
Inferior (lower)lobe bronchi
Thyroidcartilage
Cricoidcartilage
Cartilaginousring
Leftprimarybronchus
Superior (upper)lobe bronchus
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Hyaline cartilage
Ciliated epithelium
Smooth muscle
Lumen of trachea
Connective tissue
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Connectivetissue
Hyalinecartilage
Ciliatedepithelium
Lumen oftrachea
Smoothmuscle
© Ed Reschke
Thyroid gland
Incision
Trachea
Hyoidbone
Thyroidcartilage
Cricoidcartilage
Jugularnotch
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Bronchial Tree• The bronchial tree consists of branched airways leading from the trachea to the microscopic air sacs in the lungs
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Larynx
Right middle lobe
Right superior (upper) lobe
Right primary bronchus
Secondary bronchus
Right inferior (lower) lobe
Alveolar duct
Alveolus
Respiratory bronchiole
Tertiary bronchus
Terminal bronchiole
Trachea
Left superior(upper) lobe
Left inferior(lower) lobe
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• The successive divisions of the branches from the trachea to the alveoli are:1.Right and left primary bronchi2.Secondary or lobar bronchi3.Tertiary or segmental bronchi4.Intralobular bronchioles (12-14 generations)5.Terminal bronchioles6.Respiratory bronchioles7.Alveolar ducts•Alveolar sacs1.Alveoli
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© Ralph Hutchings/Visuals Unlimited
Branches of the Bronchial Tree
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Intralobular bronchiole
Blood flow
Alveolus
Smooth muscle
Alveoli
Blood flow
Blood flow
Pulmonaryartery
Pulmonaryvein
Terminalbronchiole
Respiratorybronchiole
Pulmonaryarteriole
Pulmonaryvenule
Capillary network onsurface of alveolus
AlveolarductAlveolarsac
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Capillary
Alveolus
Simple squamousepithelial cells
© McGraw-Hill Higher Education, Inc./Bob Coyle
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• The structure of the bronchus is similar to that of the trachea, but the C-shaped cartilaginous rings are replaced with cartilaginous plates where the bronchus enters the lung• These respiratory tubes become thinner and thinner, and the cell layers thin and change until the alveoli is reached• It is the alveoli that provides surface area for gas exchange
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Blood flowBlood flow
Arteriole
Alveolus
Capillary
Air
O2CO2
CO2
Alveolarwall
Venule
O2
The Respiratory Tubes
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Blood vessel Capillary Alveolus
Tissues and Organs: A Text-Atlas of Scanning Electron Microscopy, by R.G. Kessel and R.H. Kardon. © 1979 W.H. Freeman and Company
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Courtesy of the American Lung Association Bronchiole
Alveolus
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Lungs• The right and left lungs are soft, spongy, cone-shaped organs in the thoracic cavity• The right lung has three lobes and the left lung two lobes
Thyroid cartilage
Cricoid cartilage
Clavicle
Scapula
Rib cartilageSternum
Superior (upper)lobe of right lung
Middle lobeof right lung
Inferior (lower) lobe of right lung
Superior (upper) lobe of left lung
Inferior (lower) lobe of left lung
Trachea
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19.4: Breathing Mechanism• Breathing or ventilation is the movement of air from outside of the body into the bronchial tree and the alveoli
• The actions responsible for these air movements are inspiration, or inhalation, and expiration, or exhalation
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Inspiration• Atmospheric pressure due to the weight of the air is the force that moves air into the lungs• At sea level, atmospheric pressure is 760 millimeters of mercury (mm Hg)• Moving the plunger of a syringe causes air to move in or out• Air movements in and out of the lungs occur in much the same way
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Diaphragm
Air passageway
Atmospheric pressureof 760 mm Hg on theoutsideAtmospheric
pressureof 760 mm Hgon the inside
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(a) (b)
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• Intra-alveolar pressure decreases to about 758mm Hg as the thoracic cavity enlarges due to diaphragm downward movement caused by impulses carried by the phrenic nerves• Atmospheric pressure then forces air into the airways
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Diaphragm
(a) (b)
Intra-alveolarpressure(760 mm Hg)
Atmospheric pressure(760 mm Hg)
Intra-alveolarpressure(758 mm Hg)
Inspiration
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(a) (b)
Externalintercostalmuscles pullribs up and out
Diaphragmcontracts
SternummovesUp and out
Sternocleidomastoidelevates sternum
Pectoralis minorelevates ribs
Diaphragmcontracts more
Inspiration
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Expiration• The forces responsible for normal resting expiration come from elastic recoil of lung tissues and from surface tension• These factors increase the intra-alveolar pressure about 1 mm Hg above atmospheric pressure forcing air out of the lungs
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Diaphragm
Diaphragm
(a) (b)
Abdominal organsrecoil and pressdiaphragm upward
Posterior internalintercostal musclespull ribs down andinward
Abdominal organsforce diaphragmhigher
Abdominal wallmuscles contractand compressabdominal organs
Expiration
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Respiratory Air Volumes and Capacities
• Different degrees of effort in breathing move different volumes of air in and out of the lungs• This measurement of volumes is called spirometry
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Lung
vo
lum
e in
mill
ilite
rs (
mL)
6,000
5,000
4,000
3,000
2,000
1,000
0
Inspiratoryreserve volume
Tidalvolume
Residualvolume
Expiratoryreserve volume
Vitalcapacity
Inspiratorycapacity
Total lungcapacity
Functionalresidualcapacity
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Alveolar Ventilation
• The volume of new atmospheric air moved into the respiratory passages each minute is minute ventilation• It equals the tidal volume multiplied by the breathing rate• Much of the new air remains in the physiologic dead space• The tidal volume minus the physiologic dead space then multiplied by breathing rate is the alveolar ventilation rate• This is the volume of air that reaches the alveoli• This impacts the concentrations of oxygen and carbon dioxide in the alveoli
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Nonrespiratory Air Movements
• Air movements other than breathing are called nonrespiratory movements• They clear air passages, as in coughing and sneezing, or express emotions, as in laughing and crying
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19.3 Clinical Application
Respiratory Disorders That Decrease Ventilation: Bronchial Asthma and
Emphysema
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19.5: Control of Breathing
• Normal breathing is a rhythmic, involuntary act that continues when a person is unconscious• Respiratory muscles can be controlled as well voluntarily
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Respiratory Areas
• Groups of neurons in the brainstem comprise the respiratory areas that control breathing• Impulses travel on cranial nerves and spinal nerves, causing inspiration and expiration• Respiratory areas also adjust the rate and depth of breathing• The respiratory areas include:
• Respiratory center of the medulla• Respiratory group of the pons
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Diaphragm
Medulla oblongataPons
Midbrain
Dorsal respiratory group
Pontine respiratorygroup
Ventral respiratory group
Fourthventricle
Medullaryrespiratorycenter
Internal (expiratory)intercostal muscles
External (inspiratory)intercostal muscles
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Respiratory muscles
Forceful breathing
Nerve impulses Nerve impulses
Pontine respiratorygroup
Ventralrespiratorygroup
Dorsalrespiratorygroup
Medullary respiratory center
Respiratory areas
Basic rhythmof breathing
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Factors Affecting Breathing
• A number of factors affect breathing rate and depth including:
• Partial pressure of oxygen (Po2)• Partial pressure of carbon dioxide (Pco2)• Degree of stretch of lung tissue• Emotional state• Level of physical activity
• Receptors involved include mechanoreceptors and central and peripheral chemoreceptors
Carotid bodies
Aorta
Heart
Aortic bodies
Medulla oblongata
Sensory nerve(branch ofglossopharyngealnerve)
Common carotidartery
Sensory nerve(branch of vagus nerve)
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• Changes in blood pH, O2 and CO2 concentration stimulates chemoreceptors• Motor impulses can travelfrom the respiratory centerto the diaphragm and external intercostal muscles• Contraction of these muscles causes the lungs to expand stimulating mechanoreceptors in the lungs• Inhibitory impulses from the mechanoreceptors back to the respiratory center prevent overinflation of the lungs
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Respiratory center
Motor pathways
Spinal cord
Intercostal nerve
Rib
Diaphragm
Sensory pathway
Phrenic nerve
Stretch receptors
Lung
External intercostalmuscles
Vagus nerve
––
Factors Affecting Breathing
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19.6: Alveolar Gas Exchanges• The alveoli are the sites of the vital process of gas exchange between the air and the blood
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AlveoliCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Courtesy of the American Lung Association
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Capillary lumen
Alveolus
Macrophage
Capillary
Alveolus
Red blood cell
Diffusion of CO2
Diffusion of O2
Capillary endothelium
Interstitial space
Alveolar epithelium
Type I (squamous epithelial) cell of alveolar wall
Type II (surfactant-secreting) cell
Fluid withsurfactant
Respiratorymembrane
Cell ofcapillary wall
Alveolar fluid (with surfactant)
Basement membrane ofalveolar epithelium
Basement membrane ofcapillary endothelium
Respiratorymembrane
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Respiratory Membrane• Part of the wall of an alveolus is made up of cells (type II cells) that secrete pulmonary surfactant• The bulk of the wall of an alveolus consists of a layer of simple squamous epithelium (type I cells)• Both of these layers make up the respiratory membrane through which gas exchange takes place
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AS
AS
BM
IS
RBC
EP
© Imagingbody.com
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AlveolusDiffusion of CO2
Diffusion of O2
Capillary
Alveolarwall
Blood flow(from bodytissues)
Blood flow(to bodytissues)
PCO2 = 45 mm Hg
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PCO2 = 40 mm Hg
PO2 = 40 mm Hg
PO2 = 104 mm Hg
PO2 = 104 mm Hg
PCO2 = 40 mm Hg
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Diffusion Through the Respiratory Membrane
• Molecules diffuse from regions where they are in higher concentration toward regions where they are in lower concentration• It is important to know the concentration gradient• In respiration, think in terms of gas partial pressures• Gases diffuse from areas of higher partial pressure to areas of lower partial pressure• The respiratory membrane is normally thin and gas exchange is rapid
• Increased diffusion is favored with more surface area, shorter distance, greater solubility of gases and a steeper partial pressure gradient• Decreased diffusion occurs from decreased surface area
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19.6 Clinical Application
Disorders That Impair Gas Exchange: Pneumonia, Tuberculosis, and Adult
Respiratory Distress Syndrome
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19.7: Gas Transport
• Blood transports O2 and CO2 between the lungs and the body cells• As the gases enter the blood, they dissolve in the plasma or chemically combine with other atoms or molecules
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Oxygen Transport• Almost all oxygen carried in the blood is bound to the protein hemoglobin in the form of oxyhemoglobin• Chemical bonds between O2 and hemoglobin are relatively unstable• Oxyhemoglobin releases O2 into the body cells• About 75% of the O2 remains bound to hemoglobin in the venous blood ensuring safe CO2 levels and thereby pH
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AlveolusCapillary
2
2
2
(a) (b)
Blood flow(from bodytissues)
Alveolarwall
Oxygenmolecules
Hemoglobinmolecules
Diffusionof oxygen
Oxyhemoglobinmolecule
Hemoglobinmolecules
Diffusionof oxygen
Blood flow(to lungs)
BloodPO = 40 mm Hg
BloodPO = 95 mm Hg
Tissue cellsTissuePO = 40 mm Hg
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Oxyhemoglobin dissociation at 38°C
% s
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hem
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PO2(mm Hg)
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• The amount of oxygen released from oxyhemoglobin increases with: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Oxyhemoglobin dissociation at 38°C
20 mm Hg40 mm Hg80 mm Hg
PCO2 =
PO2 (mm Hg)
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Oxyhemoglobin dissociation at 38°C
% s
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7.67.47.2
pH =
PO2 (mm Hg)
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PO2 (mm Hg)
Oxyhemoglobin dissociation at various temperatures
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Carbon Dioxide Transport
• Blood flowing through capillaries gains CO2 because the tissues have a high Pco2 • The CO2 is transported to the lungs in one of three forms:
• As CO2 dissolved in plasma• As part of a compound with hemoglobin• As part of a bicarbonate ion
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Tissue cell
Cellular CO2
Plasma Red blood cell Capillary wall
Bloodflow tosystemicvenule
TissuePCO2
= 45 mm Hg
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CO2 dissolvedin plasma
PCO2 = 40 mm Hg
Bloodflow fromsystemicarteriole
CO2 combined withhemoglobin to form
carbaminohemoglobin
H2CO3
H+combineswith hemoglobin
PCO2 = 45 mm HgHCO3
- + H+
CO2 + H2O
HCO3-
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HCO3-
Red blood cell
HCO3-
Cl-
Cl-
Cl-
HCO3-
PlasmaCapillary wallCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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CO2CO2
Alveolus
Alveolar wall
Capillary wall
CO2
HCO3-
Carbaminohemoglobin
Plasma Red blood cell
PCO2 = 45 mm Hg
PCO2 = 40 mm Hg
CO2
CO2dissolvedin plasma
Blood flowfrom pulmonaryarteriole
HCO3-+ H+
H2CO3
H+ releasedfrom hemoglobin
Bloodflow topulmonaryvenule
PCO2 = 40 mm Hg
+ H2O
CO2 + hemoglobin
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19.8: Lifespan Changes• Lifespan changes reflect an accumulation of environmental influences and the effects of aging in other organ systems, and may include:
• The cilia become less active• Mucous thickening• Swallowing, gagging, and coughing reflexes slowing• Macrophages in the lungs lose efficiency• An increased susceptibility to respiratory infections• A “barrel chest” may develop• Bronchial walls thin and collapse• Dead space increasing
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Important Points in Chapter 19:Outcomes to be Assessed
19.1: Introduction
Identify the general functions of the respiratory system.
19.2: Why We Breathe
Explain why respiration is necessary for cellular survival.
19.3: Organs of the Respiratory System
Name and describe the locations of the organs of the respiratory system.
Describe the functions of each organ of the respiratory system.
19.4: Breathing Mechanism
Explain how inspiration and expiration are accomplished.
Name and define each of the respiratory air volumes and capacities.
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Important Points in Chapter 19:Outcomes to be Assessed
Calculate the alveolar ventilation rate.
List several non-respiratory air movements and explain how each occurs.
19.5: Control of Breathing
Locate the respiratory areas and explain control of normal breathing.
Discuss how various factors affect breathing.
19.6: Alveolar Gas Exchanges
Define partial pressure and explain its importance in diffusion of gases.
Describe gas exchange in the pulmonary and systemic circuits.