Chapt19 Apr Lecture

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Chapter 19APR Enhanced Lecture

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Chapter 19

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Hole’s Human Anatomyand Physiology

Twelfth Edition

Shier Butler Lewis

Chapter 19

Respiratory System

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

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

Respiratory System Overview

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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

Larynx

Bronchus

Nostril

Right lung Left lung

Soft palate

Pharynx

Epiglottis

Esophagus

FrontalsinusNasalcavityHardpalate

Oralcavity

Trachea

Nose through larynx

The Upper Respiratory Tract

Nasal cavity

Nasal septum

Hard palate

Soft palate

EpiglottisVocal cordsLarynx

Frontal sinus

Nostril

Hard palate

EpiglottisHyoid bone

Larynx

SuperiorMiddleInferior

Sphenoidal sinus

Pharyngeal tonsilNasopharynx

Palatine tonsilOropharynxLingual tonsil

Laryngopharynx

Esophagus

Tongue

Trachea

Nasalconchae

Opening ofauditory tube

Nasal Septum and Conchae

Vomer Perpendicular plate

Septal nasal cartilage

Nasal Septum

Nares Nasal cavity

Nasal septum Nasopharynx

Middle nasal concha

Inferior nasal conchae

Soft palate Uvula

Superior

Middle

Inferior

Septum

Nasal Cavity

Mucus Particle

Goblet cell

CiliaNasal cavity

Epithelial cell

(b)(a)b: © Biophoto Associates/Photo Researchers, Inc.

CiliaRespiratory epithelium

Goblet cellsLamina propria

Ciliated cells

Respiratory Epithelium

Sinuses• The sinuses are air-filled spaces in the maxillary, frontal, ethmoid, and sphenoid bones of the skull

Sinuses

Maxillary

Frontal

Ethmoid

Sphenoid

19.1 Clinical Application

The Effects of Cigarette Smoking on the Respiratory System

Frontal sinus

Nostril

Hard palate

EpiglottisHyoid bone

Larynx

SuperiorMiddleInferior

Sphenoidal sinus

Pharyngeal tonsil

Nasopharynx

Palatine tonsilOropharynxLingual tonsil

Laryngopharynx

Esophagus

Tongue

Trachea

Nasalconchae

Opening ofauditory tube

NasopharynxNasopharynx OropharynxOropharynx LaryngopharynxLaryngopharynx

Pharynx

OropharynxNasopharynx Laryngopharynx

Pharynx

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 cartilage

Hyoid bone

Thyroid cartilage

Cricoid cartilage

Hyoid bone

Epiglottic cartilage

Thyroid cartilage

Cricoid cartilage

Trachea

False vocal cord

Glottis

Epiglottis

Hyoid bone

Thyroid cartilage

Cricoid cartilage

Hyoid boneEpiglottis

Thyroid cartilage

Cricoid cartilage

False vocalcord

True vocalcord

Thyroid cartilage

Cuneiform cartilageCorniculate cartilageArytenoid cartilageTrue vocal cord

GlottisCorniculate cartilage(a)

Epiglottis

Glottis

Posterior portionof tongue

False vocal cord

True vocal cordCuneiform cartilage

Inner lining of trachea

c: © CNRI/PhotoTake

Epiglottis

Vocal cords

Larynx

Thyroid cartilage

Cricoid cartilage

Epiglottis Circothyroid ligament

Thyrohyoid membrane

Larynx - Anterior

Laryngeal cartilages

Epiglottis Thyroid cartilage

Cricoid cartilage

Arytenoid cartilages

Corniculate cartilages

Larynx - Posterior

Epiglottis Thyroid cartilage

Vestibularfold

Vocal fold

Larynx - Lateral

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

Larynx

Carina

Trachea

Superior (upper)lobe bronchus

Right primarybronchus

Middle lobebronchus

Inferior (lower)lobe bronchi

Thyroidcartilage

Cricoidcartilage

Cartilaginousring

Leftprimarybronchus

Superior (upper)lobe bronchus

Trachea

Trachea and Primary Bronchi

carina

Trachea

Hyaline cartilage

Ciliated epithelium

Smooth muscle

Lumen of trachea

Connective tissue

Connectivetissue

Hyalinecartilage

Ciliatedepithelium

Lumen oftrachea

Smoothmuscle

Thyroid gland

Incision

Trachea

Hyoidbone

ThyroidcartilageCricoidcartilage

Jugularnotch

Bronchial Tree• The bronchial tree consists of branched airways leading from the trachea to the microscopic air sacs in the lungs

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

Branches of the Bronchial Tree

• 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 bronchioles5.Terminal bronchioles6.Respiratory bronchioles7.Alveolar ducts8.Alveolar sacs9.Alveoli

Intralobular bronchiole

Blood flow

Alveolus

Smooth muscle

Alveoli

Blood flow

Pulmonaryartery

Pulmonaryvein

Terminalbronchiole

Respiratorybronchiole

Pulmonaryarteriole

Pulmonaryvenule

Capillary network onsurface of alveolus

AlveolarductAlveolarsac

Capillary

Alveolus

Simple squamousepithelial cells

Conducting bronchiole

Pulmonary artery branch

Alveolar duct

alveolar sacsAlveolar

Lung Tissue

Alveolar macrophages Pulmonary

artery branchAlveolar wall

Alveolus

Lung Tissue

The Respiratory Tubes

• 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

Blood flowBlood flow

Arteriole

Alveolus

Capillary

Alveolarwall

Venule

Blood vessel Capillary Alveolus

Courtesy of the American Lung Association Bronchiole

Alveolus

Animation:Alveolar Pressure Changes

During Inspiration and Expiration

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 cartilageCricoid cartilage

Clavicle

Scapula

Rib cartilage

Sternum

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

Right lung

Left lung

Pericardium

Pleura

Plane ofsection

Pericardialcavity

Right pleuralcavity

Visceralpleura

Parietalpleura

Left pleuralcavity

Superior lobe Middle lobe Inferior lobe

Horizontal fissure

Oblique fissure

Right Lung

Horizontal fissure

Superior lobe Inferior lobe

Left Lung

Cardiac impression

Chest X-ray and Bronchogram

Animation:The Pleural Membranes

Pleural Membranes

Parietal pleura Visceral pleura 50

Lung Irritants

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

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

Diaphragm

Air passageway

Atmospheric pressureof 760 mm Hg on theoutside

Atmosphericpressureof 760 mm Hgon the inside

(a) (b)

• 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

Inspiration

Diaphragm

(a) (b)

Intra-alveolarpressure(760 mm Hg)

Atmospheric pressure(760 mm Hg)

Intra-alveolarpressure(758 mm Hg)

(a) (b)

Externalintercostalmuscles pullribs up and out

Diaphragmcontracts

SternummovesUp and out

Sternocleidomastoidelevates sternum

Pectoralis minorelevates ribs

Diaphragmcontracts more

Inspiration

Thoracic Cavity Dimensional Changes

Inspiratory Muscles

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

Diaphragm

(a) (b)

Abdominal organsrecoil and pressdiaphragm upward

Posterior internalintercostal musclespull ribs down andinward

Abdominal organsforce diaphragmhigher

Abdominal wallmuscles contractand compressabdominal organs

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

illili

Inspiratoryreserve volume

Tidalvolume

Residualvolume

Expiratoryreserve volume

Vitalcapacity

Inspiratorycapacity

Total lungcapacity

Functionalresidualcapacity

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

Animation:Alveolar Ventilation

and Anatomic Dead Space

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

Respiratory Disorders That Decrease Ventilation: Bronchial

Asthma and Emphysema

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

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

Diaphragm

Medulla oblongataPons

Midbrain

Dorsal respiratory group

Pontine respiratorygroup

Ventral respiratory group

Fourthventricle

Medullaryrespiratorycenter

Internal (expiratory)intercostal muscles

External (inspiratory)intercostal muscles

Respiratory muscles

Forceful breathing

Nerve impulses Nerve impulses

Pontine respiratorygroup

Ventralrespiratorygroup

Dorsalrespiratorygroup

Medullary respiratory center

Respiratory areas

Basic rhythmof breathing

Animation:Movement of Oxygenand Carbon Dioxide

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

Aortic bodies

Medulla oblongataSensory nerve(branch ofglossopharyngealnerve)

Common carotidartery

Sensory nerve(branch of vagus nerve)

Factors Affecting Breathing• 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

Respiratory center

Motor pathways

Spinal cord

Intercostal nerve

Diaphragm

Sensory pathway

Phrenic nerve

Stretch receptors

External intercostalmuscles

Vagus nerve

––

Exercise and Breathing

19.6: Alveolar Gas Exchanges• The alveoli are the sites of the vital process of gas exchange between the air and the blood

Courtesy of the American Lung Association

Capillary lumen

Alveolus

Macrophage

Capillary

Alveolus

Red blood cell

Diffusion of CO2

Diffusion of O2

Capillary endothelium

Interstitial space

Alveolar epithelium

Type I(squamousepithelial) cell of alveolar wall

Type II(surfactant-secreting) cell

Fluid withsurfactant

Respiratorymembrane Cell of

capillary wall

Alveolar fluid(with surfactant)

Basement membrane ofalveolar epithelium

Basement membrane ofcapillary endothelium

Respiratorymembrane

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

Alveolus Diffusion of CO2

Diffusion of O2

Capillary

Alveolarwall

Blood flow(from bodytissues)

Blood flow(to bodytissues)

PCO2 = 45 mm Hg

PCO2 = 40 mm Hg

PO2 = 40 mm Hg

PO2 = 104 mm Hg

PO2 = 104 mm HgPCO2 = 40 mm Hg

Animation:Gas Exchange During Respiration

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

Effects of High Altitude

Disorders That Impair Gas Exchange: Pneumonia, Tuberculosis, and Adult

Respiratory Distress Syndrome

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

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

AlveolusCapillary

(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

Oxyhemoglobin dissociation at 38°C

100 40 50 60 70 9080 100 110 120 130 14020 30PO2(mm Hg)

• The amount of oxygen released from oxyhemoglobin increases with:

100 40 50 60 70 9080 100 110 120 130 14020 30

20 mm Hg40 mm Hg80 mm Hg

PCO2 =

PO2 (mm Hg)

100 40 50 60 70 9080 100 110 120 130 14020 30

7.67.47.2

PO2 (mm Hg)

100 40 50 60 70 9080 100 110 120 130 14020 30

PO2 (mm Hg)Oxyhemoglobin dissociation at various temperatures

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

Tissue cell

Cellular CO2

Plasma Red blood cell Capillary wall

Bloodflow tosystemicvenule

TissuePCO2

= 45 mm Hg

CO2 dissolvedin plasma

PCO2 = 40 mm Hg

Bloodflow fromsystemicarteriole

CO2 combined withhemoglobin to form

carbaminohemoglobin

H+combineswith hemoglobin

PCO2 = 45 mm HgHCO3

- + H+

CO2 + H2O

Red blood cell

CO2CO2

Alveolus

Alveolar wall

Capillary wall

Carbaminohemoglobin

Plasma Red blood cell

PCO2 = 45 mm Hg

PCO2 = 40 mm Hg

CO2dissolvedin plasma

Blood flowfrom pulmonaryarteriole

HCO3-+ H+

H+ releasedfrom hemoglobin

Bloodflow topulmonaryvenule

PCO2 = 40 mm Hg

CO2 + hemoglobin

Animation:Changes in the Partial Pressuresof Oxygen and Carbon Dioxide

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

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.

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.

Describe the structure and function of the respiratory membrane.

19.7: Gas Transport

Explain how the blood transports oxygen and carbon dioxide.

19.8: Lifespan Changes

Describe the effects of aging on the respiratory system.

Quiz 19Complete Quiz 19 now!

Read Chapter 20.

Chapt19 Apr Lecture

Health & Medicine