Download The Respiratory System

The Respiratory System
• Cells continually use O2
& release CO2
• Respiratory system
designed for gas
exchange
• Cardiovascular system
transports gases in blood
• Failure of either system
– rapid cell death from O2
starvation
Human Lungs
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Respiratory System Anatomy
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Nose
Pharynx = throat
Larynx = voicebox
Trachea = windpipe
Bronchi = airways
Lungs
Locations of infections
– upper respiratory tract is above vocal cords
– lower respiratory tract is below vocal cords
External Nasal Structures
• Skin, nasal bones, & cartilage lined with mucous membrane
• Openings called external nares or nostrils
Nose -- Internal Structures
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Large chamber within the skull
Roof is made up of ethmoid and floor is hard palate
Internal nares are openings to pharynx
Nasal septum is composed of bone & cartilage
Bony swelling or conchae on lateral walls
Functions of the Nasal Structures
• Olfactory epithelium for sense of smell
• Pseudostratified ciliated columnar with goblet
cells lines nasal cavity
– warms air due to high vascularity
– mucous moistens air & traps dust
– cilia move mucous towards pharynx
• Paranasal sinuses open into nasal cavity
– found in ethmoid, sphenoid, frontal & maxillary
– lighten skull & resonate voice
Pharynx
• Muscular tube (5 inch long) hanging from skull
– skeletal muscle & mucous membrane
• Extends from internal nares to cricoid cartilage
• Functions
– passageway for food and air
– resonating chamber for speech production
– tonsil (lymphatic tissue) in the walls protects
entryway into body
• Distinct regions -- nasopharynx, oropharynx and
laryngopharynx
Regions of Pharynx
Nasopharynx: passageway for air only
Oropharynx and Laryngopharnx: passageway for food & air
Cartilages of the Larynx
• Thyroid cartilage forms Adam’s apple
• Epiglottis---leaf-shaped piece of elastic cartilage
– during swallowing, larynx moves upward
– epiglottis bends to cover glottis
• Cricoid cartilage---ring of cartilage attached to
top of trachea
• Pair of arytenoid cartilages sit upon cricoid
– many muscles responsible for their movement
– partially buried in vocal folds (true vocal cords)
Larynx
Anterior
Posterior
• Cartilage & connective tissue tube
• Anterior to C4 to C6
• Constructed of 3 single & 3 paired cartilages
Vocal Cords
• False vocal cords (ventricular folds) found above
vocal folds (true vocal cords)
• True vocal cords attach to arytenoid cartilages
Trachea
• Size is 5 in long & 1in diameter
• Extends from larynx to T5 anterior to the
esophagus and then splits into bronchi
• Layers
– mucosa = pseudostratified columnar with cilia & goblet
– submucosa = loose connective tissue & seromucous
glands
– hyaline cartilage = 16 to 20 incomplete rings
• open side facing esophagus contains trachealis m. (smooth)
• internal ridge on last ring called carina (cough reflex)
– adventitia binds it to other organs
Histology of the Trachea
• Ciliated pseudostratified columnar epithelium
• Hyaline cartilage as C-shaped structure closed by
trachealis muscle
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Trachea and Bronchial Tree
Airway Epithelium
• Ciliated pseudostratified columnar epithelium with goblet
cells produce a moving mass of mucus.
Bronchi and Bronchioles
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Primary bronchi supply each lung
Secondary bronchi supply each lobe of the lungs (3 right + 2 left)
Tertiary bronchi supply each bronchopulmonary segment
Repeated branchings called bronchioles form a bronchial tree
Histology of Bronchial Tree
• Epithelium changes from pseudostratified ciliated
columnar to nonciliated simple cuboidal, and
finally to simple squamous as pass deeper into
lungs
• Incomplete rings of cartilage replaced by rings of
smooth muscle & then connective tissue
– sympathetic NS & adrenal gland release epinephrine
that relaxes smooth muscle & dilates airways
– asthma attack or allergic reactions constrict distal
bronchiole smooth muscle
Pleural Membranes & Pleural Cavity
• Visceral pleura covers lungs --- parietal pleura lines
ribcage & covers upper surface of diaphragm
• Pleural cavity is potential space between ribs & lungs
Gross Anatomy of Lungs
• Base, apex, cardiac notch
• Oblique & horizontal fissure in right lung results in 3 lobes
• Oblique fissure only in left lung produces 2 lobes
Mediastinal Surface of Lungs
• Blood vessels & airways enter lungs at hilus
• Covered with pleura (parietal becomes visceral)
Lobules
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Structures within a Lobule of Lung
• Branchings of single
arteriole, venule &
bronchiole are wrapped by
elastic CT
• Respiratory bronchiole
– simple squamous
• Alveolar ducts surrounded
by alveolar sacs & alveoli
– sac is 2 or more alveoli
sharing a common opening
Histology of Lung Tissue
Photomicrograph of
lung tissue showing
bronchioles, alveoli
and alveolar ducts.
Cells Types of the Alveoli
• Type I alveolar cells
– simple squamous cells where gas exchange occurs
• Type II alveolar cells
– free surface has microvilli
– secrete alveolar fluid containing surfactant
• Alveolar dust cells
– wandering macrophages remove debris
Alveolar-Capillary Membrane
• Respiratory membrane = 1/2 micron thick
• Exchange of gas from alveoli to blood
• 4 Layers of membrane to cross
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alveolar epithelial wall of type I cells
alveolar epithelial basement membrane
capillary basement membrane
endothelial cells of capillary
• Vast surface area = handball court
Details of Respiratory Membrane