Download Respiratory Membrane

Respiratory System
Overview of the Respiratory
System’s Job
• Major Duty
– Respiration
• Other important aspects
– pH control
– Vocalization
– Processing incoming air
– Protection
– Metabolism (ACE)
• What structures allow for these events?
Functional Anatomy of the Respiratory System
• Respiratory organs
– Nose, nasal cavity, and paranasal sinuses
– Pharynx, larynx, and trachea
– Lungs
• Bronchi and smaller branches and alveoli • Divided into:
– Conducting zone
– Respiratory zone
The Nose
• Functions
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Provides an airway for respiration
Moistens and warms air
Filters inhaled air
Resonating chamber for speech
• also acting as a resonator are?
– Houses olfactory receptors
• Characteristics
– Size variation due to differences in nasal cartilages
– Skin is thin – contains many sebaceous glands
The Nasal Cavity
• External nares – nostrils
• Divided by – nasal septum
• Continuous with nasopharynx
– Posterior nasal apertures – choanae
• Contains the nasal conchae
Basic Anatomy of the Upper Respiratory Tract
Upper Respiratory Tract –
The Mucosa
• Two types of mucosa
– Olfactory mucosa – houses olfactory receptors
– Respiratory mucosa – lines nasal cavity • Consists of: – Pseudostratified ciliated columnar epithelium
– Goblet cells within epithelium – Underlying layer of lamina propria • Cilia move contaminated mucus posteriorly
Upper Respiratory Tract –
The Pharynx
• Funnel‐shaped passageway
• Connects nasal cavity and mouth
• Divided into three locations
– Nasopharynx, oropharynx, and laryngopharynx • Type of mucosal lining varies along its length The Upper Respiratory Tract –
The Nasopharynx
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Superior to the point where food enters
Only an air passageway
Closed off during swallowing
Pharyngeal tonsil (adenoids) – Located on posterior wall
– Destroys entering pathogens
– Have ciliated epithelial tufts
• Major epithelium present is stratified squamous with microvilli present
• Contains the opening to the pharyngotympanic (auditory) tube The Upper Respiratory Tract –
The Oropharynx
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Arch‐like entranceway – fauces
Extends from soft palate to the epiglottis
Epithelium is stratified squamous epithelium
Two types of tonsils in the oropharynx
– Palatine tonsils – in the lateral walls of the fauces – Lingual tonsils – embedded in the posterior surface of the tongue
The Upper Respiratory Tract –
The Laryngopharynx
• Passageway for both food and air
– Starts at tip of epiglottis
– Ends at start of esophagus
• Lined with stratified squamous epithelium
• Continuous with the oropharynx anteriorly and the esophagus posteriorly
The Larynx
• Voice production – Length/Tension – adjusted by cricoarytnoid muscles & vocalis (thyroarytenoid) muscles
• Affect?
– Loudness ‐
• Sphincter function of the larynx
– Valsalva maneuver • Food vs. Air
• Innervation of the larynx
– Via the vagus nerve’s recurrent laryngeal branch
Anatomy of the Larynx
The Trachea
• Descends into the mediastinum
• Divides into two main bronchi
• C‐shaped cartilage rings
Bronchi in the Conducting Zone
• Bronchial tree –
extensively branching respiratory passageways
• Primary bronchi (main bronchi) –
largest bronchi • Right main bronchi – wider and shorter than the left
Bronchi in the Conducting Zone
• Secondary (lobar) bronchi – Three on the right – Two on the left
• Tertiary (segmental) bronchi – Branch into each lung segment (bronchopulumonary segments)
• Bronchioles – little bronchi, less than 1 mm in diameter
• Terminal bronchioles – less than 0.5 mm in diameter
Bronchopulmonary Segments
Figure 21.14a
Changes in Tissue Composition along Conducting Pathways
• Supportive connective tissues change
– C‐shaped rings replaced by cartilage plates
• Epithelium changes
– First, pseudostratified ciliated columnar
– Replaced by simple columnar, then simple cuboidal epithelium
• Smooth muscle becomes important
The Respiratory Zone
• Consists of air‐exchanging structures
• Respiratory bronchioles – branch from terminal bronchioles
– Lead to alveolar ducts
• Alveolar ducts – branch from respiratory bronchioles
– Lead to alveolar sacs (alveoli)
Structures of the Respiratory Zone
Anatomy of Alveoli and the Respiratory Membrane
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Respiratory Membrane
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alveolar component
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capillary component
The Respiratory Zone
• Alveoli consist of
– Type I alveolar cells
– Type II alveolar cells (Septal Cells)
• Scattered among type I cells
• Cuboidal epithelial cells
• Secrete surfactant – Dust Cells • Aka – free alveolar macrophages
– Basal lamina
Microscopic Anatomy of Alveoli and the Respiratory Membrane
The Pleurae
• A double‐layered sac surrounding each lung
– Parietal pleura
– Visceral pleura
• Pleural cavity – Potential space between the visceral and parietal pleurae
• Pleurae help divide the thoracic cavity – Central mediastinum – Two lateral pleural compartments Gross Anatomy of the Lungs
• Anterior View of Thoracic Structures
Lung
Diagram of the Pleurae and Pleural Cavities
Blood Supply and Innervation of the Lungs
• Pulmonary arteries – deliver oxygen‐poor blood to the lungs
• Pulmonary veins – carry oxygenated blood to the heart
• Innervation
– Sympathetic, parasympathetic, and visceral sensory fibers
• Parasympathetic – constrict airways
• Sympathetic – dilate airways
The Mechanisms of Ventilation
• Two phases of pulmonary ventilation
– Inspiration – inhalation – Expiration – exhalation Inspiration
• In order to get air into the lungs, a pressure gradient must exist.
– Action of the diaphragm
• diaphragm flattens
– Action of intercostal muscles
• contraction raises the ribs
– Deep inspiration requires • Scalenes, sternocleidomastoid, and pectoralis minor
• Erector spinae – extends the back
• All this increases the thoracic volume which corresponds to a decrease in intra‐alveolar pressure (who’s gas law?)
Expiration
• Quiet expiration – chiefly a passive process
– Inspiratory muscles relax
– Diaphragm moves superiorly
– Volume of thoracic cavity decreases
• Forced expiration – an active process
– Produced by contraction of: • The oblique and transversus abdominis muscles Changes in Thoracic Volume
Changes in Thoracic Volume
Neural Controls of Ventilation
• Respiratory centers –
generate baseline respiration rate
– in medulla oblongata
– in the pons
• Chemoreceptors – Central and Peripheral
• Other receptors