Chapter 23: The Respiratory System

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Chapter 23 The Respiratory System

• BIO 211 Lab
• Instructor Dr. Gollwitzer

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• Today in class we will discuss
• The structural divisions of the respiratory
  system
• Identify the components of the respiratory system
• The respiratory tract
• Define the respiratory tract
• Identify the functional divisions of the
  respiratory tract
• The respiratory mucosa
• The respiratory mucosa and list its functions
• The respiratory defense system and look at some
  of its components
• The upper respiratory system and its components
• Nose and nasal cavity
• Pharynx
• Paranasal sinuses
• The lower respiratory system and its components
• Pharynx
• Larynx

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Structural Divisions

• Upper respiratory system
• Above the larynx
• Includes nose, nasal cavity, paranasal sinuses,
  pharynx
• Filters, warms, and humidifies incoming air
  (conditioning process)
• Protects more delicate structures of lower
  respiratory system
• Cools and dehumidifies outgoing air
• Lower respiratory system
• From larynx down
• Includes larynx (voice box), trachea (windpipe),
  bronchi, bronchioles, alveoli

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Figure 23-1 The Components of the Respiratory
System
Frontal sinus
Nasal cavity
Nasal conchae
Sphenoidal sinus
Nose
Internal nares
Tongue
UPPERRESPIRATORYSYSTEM
Pharynx
Hyoid bone
Larynx
LOWERRESPIRATORYSYSTEM
Esophagus
Trachea
Clavicle
Bronchus
Bronchioles
RIGHTLUNG
Ribs
Diaphragm
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Respiratory Tract

• Airways that carry air to/from exchange
  surfaces of lungs
• Functional divisions
• Conducting portion
• Nose to terminal bronchioles
• Respiratory portion
• Respiratory bronchioles, alveolar ducts, and
  alveoli
• Alveoli air-filled pockets within lung where
  gas exchange takes place

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Respiratory Mucosa

• Mucous membrane
• Pseudostratified columnar epithelium areolar
  tissue
• Lines conducting portion of respiratory tract
• Underlying mucous glands ? mucus
• Responsible for success of air conditioning
  process (prior to it reaching conducting
  respiratory portion)
• Filters (traps dust and particles), warms,
  humidifies
• When air reaches alveoli, most foreign particles
  and pathogens removed and temperature and
  humidity at acceptable levels

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Figure 23-2bc The Respiratory Epithelium of the
Nasal Cavity and Conducting System
Movementof mucusto pharynx
Ciliated columnarepithelial cell
Mucous cell
Cilia
Stem cell
Laminapropria
Nucleus ofcolumnarepithelial cell
Mucus layer
Mucous cell
Lamina propria
Basementmembrane
Stem cell
A diagrammatic view of therespiratory epithelium
of the trachea, indicating the direction of
mucus transport inferior to the pharynx.
The sectional appearance ofthe respiratory
epithelium, apseudostratified ciliated columnar
epithelium.
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Respiratory Mucosa

• Respiratory defense system
• Goblet cells (single cell exocrine glands) and
  mucous glands
• Secrete sticky mucus that bathes exposed surfaces
• Cilia
• Sweep mucous and trapped debris or microorganisms
  toward pharynx (mucus escalator)
• Mucus is swallowed and exposed to acids/enzymes
  of the stomach

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Upper Respiratory System

• Nose and nasal cavity
• Pharynx
• Paranasal sinuses

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Figure 23-3c Structures of the Upper Respiratory
System (Part 1 of 1)
Frontal sinus
Nasal conchae
Nasal cavity
Superior
Middle
Internal nares
Inferior
Entrance to auditory tube
Nasal vestibule
Pharyngeal tonsil
Pharynx
External nares
Hard palate
Nasopharynx
Oral cavity
Oropharynx
Laryngopharynx
Tongue
Soft palate
Palatine tonsil
Mandible
Epiglottis
Lingual tonsil
Hyoid bone
Glottis
Thyroid cartilage
Vocal fold
Cricoid cartilage
Trachea
Esophagus
Thyroid gland
The nasal cavity and pharynx, as seen in
sagittalsection with the nasal septum removed
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Nose and Nasal Cavity

• External naris (pl es) nostril opening
• Nasal cavity (2) space within nose
• Nasal vestibule space within flexible tissues
  of the nose at the entrance to the nasal cavity
• Coarse hairs prevent entry of foreign objects
• Nasal septum (that divides nasal cavity into two
  areas)
• Bony portion fusion of parts of vomer and ethmoid
  bones
• Anterior portion formed from hyaline cartilage
  supports bridge and tip of nose

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Nose and Nasal Cavity

• Superior, middle, inferior nasal conchae
• Project from lateral walls of nasal cavity toward
  the nasal septum
• Air bounces off, churns creates turbulence ?
  promotes filtration, warms, and humidifies
• Also creates eddy currents ? bring olfactory
  stimuli to receptors
• AKA turbinates
• Superior, middle, inferior nasal meatuses
  (passages)
• Narrow grooves through which air flows between
  adjacent conchae

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Upper Respiratory System
Figure 23-3
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Nose and Nasal Cavity

• Olfactory region
• In superior nasal cavity on either side of nasal
  septum
• Has olfactory epithelium
• Specialized receptors that provide sense of
  smell)
• Connected to olfactory bulb and tract (N I)

Figure 171a
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Nose and Nasal Cavity

• Hard palate
• Separates oral and nasal cavities
• Forms floor of nasal cavity, roof of oral cavity
• Formed by maxillary and palatine bones
• Soft palate
• Fleshy extension posterior to hard palate
• Marks boundary between nasopharynx and lower
  pharynx
• Uvula dangling process on posterior margin
  helps prevent food from entering pharynx
  prematurely
• Internal naris (pl es)
• Opening from nasal cavity into nasopharynx
  posterior to conchae

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Pharynx

• Shared by respiratory and digestive systems
• Extends from internal nares to entrances to
  larynx and esophagus
• Divided into
• Nasopharynx
• Oropharynx
• Laryngopharynx

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Pharynx

• Nasopharynx
• Superior portion of pharynx
• Separated from oral cavity by soft palate
• Contains pharyngeal tonsils, entrances to
  auditory (eustachian) tubes
• Oropharynx
• Middle part of pharynx (inferior to nasopharynx)
• Posterior portion of oral cavity
• Laryngopharynx
• Inferior part of pharynx
• Between hyoid bone and entrance to larynx and
  esophagus

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Figure 23-3c Structures of the Upper Respiratory
System (Part 1 of 1)
Frontal sinus
Nasal conchae
Nasal cavity
Superior
Middle
Internal nares
Inferior
Entrance to auditory tube
Nasal vestibule
Pharyngeal tonsil
Pharynx
External nares
Hard palate
Nasopharynx
Oral cavity
Oropharynx
Laryngopharynx
Tongue
Soft palate
Palatine tonsil
Mandible
Epiglottis
Lingual tonsil
Hyoid bone
Glottis
Thyroid cartilage
Vocal fold
Cricoid cartilage
Trachea
Esophagus
Thyroid gland
The nasal cavity and pharynx, as seen in
sagittalsection with the nasal septum removed
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Paranasal Sinuses

• Sinuses of the frontal, sphenoid, ethmoid and
  paired maxillary and palatine bones
• Spaces in the bones surrounding nasal passages
• Lighten skull weight
• Lined with mucous membranes
• Produce mucous secretions (plus tears through
  nasolacrimal ducts)
• Lubricate and clean nasal cavity surfaces
• Secretions increase in response to changes in
• Temperature and humidity
• Viral or bacterial infection
• Irritating vapors

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Lower Respiratory System

• Larynx (voice box)
• Trachea (windpipe)
• Bronchi
• Bronchioles
• Alveoli

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Larynx

• Air leaves pharynx and enters larynx through
  glottis (opening)
• Comprised of incomplete cartilaginous walls
  stabilized by ligaments and skeletal muscles
• Cartilage surrounds and protects glottis
• Walls formed by 9 cartilages
• 3 Pairs of small cartilages
• 3 Large, unpaired cartilages
• Thryoid cartilage, cricoid cartilage, epiglottic
  cartilage

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Figure 23-4c
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Larynx

• Thyroid cartilage
• Largest, anterior (hyaline) cartilage
• Protects glottis and entrance to trachea
• Forms anterior and lateral walls of larynx
• Anterior laryngeal prominence (Adams apple)
• Cricoid cartilage
• Inferior to thyroid cartilage
• Ring-like hyaline cartilage
• Also protects glottis and entrance to trachea
• Epiglotic cartilage (epiglottis)
• Elastic cartilage
• Forms lid over the glottis
• Prevents entry of liquids or food into the larynx
  and rest of respiratory tract

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Larynx

• Laryngeal epithelial folds
• Vestibular folds (false vocal cords)
• Superior folds in lateral walls
• Help prevent foreign objects from entering
  glottis
• Protect delicate vocal folds
• Vocal folds (true vocal cords)
• Inferior folds in lateral walls
• Also guard entrance to glottis
• Involved in production of sounds
• Ventricle of larynx
• Space between epithelial folds

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Figure 23-5
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• Today in class we will continue our discussion
  of
• The lower respiratory system and its components
• Pharynx
• Larynx
• Trachea
• Bronchi
• Lungs
• Bronchial tree
• Bronchioles
• Alveolar ducts
• Alveolar sac
• Alveoli of the lungs
• Respiratory membrane
• The blood supply to and from the lungs
• Muscles involved in respiration
• Respiratory pathology and diseases

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Trachea

• Tough, flexible tube
• Comprised of
• 15-20 C-shaped/tracheal cartilages (hyaline)
• Tracheal ligaments bind cartilages together
• Carina internal ridge at end of trachea that
  separates bronchi
• Branches to form R and L primary bronchi
• Tracheostomy
• Insertion of tube into trachea to bypass blocked
  or damaged trachea

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Figure 23-6a
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Lungs

• In thoracic cavity (walls are ribcage, floor is
  diaphragm)
• Lie within two pleural cavities separated by
  mediastinum (central tissue mass)
• Lined by pleura (serous membranes, like
  pericardium)
• Parietal pleura covers inner surface of
  thoracic (chest) wall and extends over diaphragm
  and mediastinum
• Visceral pleura covers outer surfaces of lungs,
  extending into fissures between lobes
• Pleurae secrete pleural fluid ? moist, slippery
  coating that lubricates, reducing friction
  between parietal and visceral surfaces as you
  breathe
• Pleurisy normal pleural fluid coating unable to
  prevent friction ? pain and pleural inflammation,
  breathing becomes difficult

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Relationship between Lungs and Heart
Figure 238
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Lungs

• Hilus where root (primary bonchus, blood
  vessels, nerves) enters
• Shape blunt cone
• Superior apex extends into base of neck
  superior to first rib
• Inferior base rests on superior surface of
  diaphragm
• Separated into lobes divided by fissures
• Right lung
• Superior, middle, inferior lobes (N3)
• Horizontal and oblique fissures
• Left lung
• Superior, inferior lobes (N2)
• Oblique fissure
• Narrower than R lung (heart and great vessels
  project into left thoracic cavity)
• Longer than R lung (diaphragm rises on right side
  to accommodate liver mass)
• Cardiac notch accommodates heart

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Figure 23-7c, 7th edition
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Figure 23-7b, 7th edition
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Lungs

• Pulmonary lobules
• Formed by interlobular septa (finest partitions)
• Each supplied by branches of pulmonary arteries,
  veins, and respiratory passageways

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Bronchial Tree

• Formed by primary bronchi and branches
• Progresses from less cartilage to more smooth
  muscle
• R and L primary bronchi (extrapulmonary bronchi)
• Also have cartilaginous C-shaped supporting rings
• Carina (ridge at base of trachea) separates two
  bronchi
• R primary bronchus
• Larger in diameter than L
• Steeper angle toward lung than L
• Route of most foreign objects
• Each primary bronchus branches to form secondary
  bronchi

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Figure 23-9a, 7th edition
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Bronchial Tree

• Intrapulmonary bronchi (inside lungs)
• Secondary bronchi
• One to each lobe (R 3 L 2)
• In each lobe, secondary bronchi branch to form
  tertiary bronchi
• Tertiary bronchi
• Each supplies air to specific region of one lung
  bronchopulmonary segment (8-10/lung)
• Branch to form bronchioles

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Bronchial Tree

• Bronchioles
• Arterioles of respiratory system
• Walls dominated by smooth muscle
• ANS controls diameter and airflow
• Bronchodilation enlargement of airway diameter
  ? decreased resistance
• Brochoconstriction reduction of airway diameter
  ? increased resistance.
• Also occurs in asthma and allergic reaction
  (e.g. anaphylaxis, in response to histamine
  release by basophils and mast cells)
• Each bronchiole ? 6,500 terminal bronchioles

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Bronchial Tree

• Terminal bronchioles
• Each one delivers air to a single pulmonary
  lobule
• Pulmonary lobule
• Smallest compartments of lung divided by
  interlobular septa
• Each one supplied by pulmonary arteries and veins
• Within lobule, each bronchiole branches to form
  several respiratory bronchioles
• Respiratory bronchioles
• Thinnest, most delicate branches
• Deliver air to gas exchange surfaces of lungs
• Lined by simple cuboidal epithelium (also lines
  terminal bronchioles)

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Bronchial Tree

• Summary
• Primary bronchus (to lung) ?
• Secondary bronchus (to lobe) ?
• Tertiary bronchus ?
• Bronchiole ?
• Terminal bronchiole (to lobule) ?
• Respiratory bronchioles ?
• Alveolar ducts ?
• Alveolar sac ?
• Alveolus

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Alveolar Ducts and Alveoli

• Respiratory bronchioles ? alveolar ducts which
  end at alveolar sacs
• Alveolar sacs common chambers connected to
  multiple individual alveoli
• Alveoli (sing. alveolus)
• Blind pockets at end of respiratory tree
• Sites of gas exchange with blood
• 50 million alveoli per lung ? open, spongy
  appearance

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Alveolar Ducts and Alveoli

• Alveolar epithelium
• Lines exchange surfaces of alveoli
• Consists of simple squamous epithelium
• Very thin, delicate
• aka Type 1 cells
• Contains septal cells (Type II cells)
• Produce surfactant
• Surfactant
• Oily secretion, mixture of phospholipids and
  proteins
• Coats alveolar surface
• Reduces surface tension so alveoli dont collapse
• Alveolar macrophages (dust cells)
• Patrol epithelial surfaces, phagocytosing
  particles

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Alveolar Ducts and Alveoli

• Pores of Kohn small openings in wall between
  alveoli
• Each alveolus surrounded by
• Extensive capillary network
• For gas exchange (O2 and CO2)
• Elastic fibers
• Recoil during exhalation
• Reduce size of alveolus and helps push air out of
  lungs

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Figure 23-9b
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Respiratory Membrane

• Site of gas exchange
• 3-part structure
• Squamous epithelial lining of alveolus
• Endothelial cells lining adjacent capillary
• Fused basement membranes that lie between
  alveolar and endothelial cells
• Diffusion very rapid
• Distance is very small
• Both O2 and CO2 are lipid soluble
• Membranes do not pose barrier between blood and
  alveolar air spaces

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Figure 23-11c
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Figure 23-12
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Blood Supply to/from Lungs

• To/from respiratory exchange surfaces
• Pulmonary artery enters lungs at hilus and
  branches within bronchi
• Each lobule receives a pulmonary arteriole (and
  venule)
• Network of (pulmonary) capillaries surrounds each
  alveolus as part of respiratory membrane
• Blood from alveolar capillaries passes through
  pulmonary venules (also 1/lobule) to pulmonary
  veins
• Returns to L atrium
• To/from conducting passageways
• Capillaries supplied by bronchial arteries
• Provide O2 and nutrients to tissues of
  respiratory tract
• Venous blood flows into pulmonary veins
• Returns to L atrium

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Respiratory Muscles

• Most important
• Diaphragm
• External intercostals (raise ribs)
• Accessory muscles
• Kick in when breathing deeply/frequently
• e.g.,
• Internal intercostals
• Pectoralis minor
• Sternocleidomastoid
• Serratus anterior

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Figure 23-16, 7th edition
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Respiratory Pathology/Diseases

• Cystic fibrosis (CF)
• Lethal inherited disease
• Respiratory mucosa produces dense, viscous mucus
  that cannot be transported by respiratory defense
  system
• Mucus blocks smaller respiratory passageways,
  reduces diameter of airways, makes breathing
  difficult
• Inactivation of normal respiratory defenses leads
  to frequent bacterial infections
• Tuberculosis (TB)
• Results from bacterial infection of lungs
  (Mycobacterium tuberculosis)
• May colonize respiratory passageways,
  interstitial spaces, alveoli, or combination
• Symptoms variable, but generally include
  coughing, chest pain, fever, night sweats,
  fatigue, weight loss

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Respiratory Pathology/Diseases

• Pneumonia
• Develops from pathogenic infection or anything
  else that causes inflammation of lung lobules
• As inflammation occurs, fluids leak into alveoli,
  respiratory bronchioles swell and constrict
• Respiratory function deteriorates
• More likely when respiratory defenses compromised
  (e.g. epithelial damage from smoking, breakdown
  of immune system with AIDS)
• Pulmonary embolism
• Pulmonary system blood pressure low (lt 30 mm Hg)
• Pulmonary vessels can easily become blocked by
  small blood clots, fat masses, air bubbles in
  pulmonary arteries
• Stops blood flow to group of lobules or alveoli
• Alveoli permanently collapse, pulmonary
  resistance increases, strains heart, unable to
  maintain cardiac output ? CHF (congestive heart
  failure)