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Questions and Answers
Which structure is located at the apex of the lung?
Which structure is located at the apex of the lung?
What is the primary function of the hilum of the lung?
What is the primary function of the hilum of the lung?
How many lobes does the right lung have?
How many lobes does the right lung have?
Which term describes the smallest subdivisions of the lungs?
Which term describes the smallest subdivisions of the lungs?
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In which location is the cardiac notch found?
In which location is the cardiac notch found?
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Which fissure separates the lobes of the left lung?
Which fissure separates the lobes of the left lung?
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What is the costal surface of the lung?
What is the costal surface of the lung?
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Which structure lies in the mediastinum?
Which structure lies in the mediastinum?
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What is the main functional difference between the right and left main bronchi?
What is the main functional difference between the right and left main bronchi?
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What characterizes the transition from bronchi to bronchioles?
What characterizes the transition from bronchi to bronchioles?
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Which structures primarily contribute to gas exchange in the lungs?
Which structures primarily contribute to gas exchange in the lungs?
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What is the role of type II alveolar cells?
What is the role of type II alveolar cells?
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What is the approximate thickness of the air-blood barrier?
What is the approximate thickness of the air-blood barrier?
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What feature of alveoli aids in equalizing air pressure throughout the lung?
What feature of alveoli aids in equalizing air pressure throughout the lung?
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How many lobar (secondary) bronchi are found on the left side?
How many lobar (secondary) bronchi are found on the left side?
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Which component is reduced in number as the airways transition from bronchi to bronchioles?
Which component is reduced in number as the airways transition from bronchi to bronchioles?
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What is the primary function of the pulmonary veins?
What is the primary function of the pulmonary veins?
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Which lobe of the lung has the highest number of segments?
Which lobe of the lung has the highest number of segments?
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What distinguishes systemic circulation from pulmonary circulation?
What distinguishes systemic circulation from pulmonary circulation?
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Where do bronchial arteries arise from?
Where do bronchial arteries arise from?
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What role does pleural fluid play in the thoracic cavity?
What role does pleural fluid play in the thoracic cavity?
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Which of the following does NOT supply blood to the alveoli?
Which of the following does NOT supply blood to the alveoli?
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What is the relationship between the parietal pleura and the thoracic wall?
What is the relationship between the parietal pleura and the thoracic wall?
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Which component of lung anatomy is responsible for carrying most venous blood back to the heart?
Which component of lung anatomy is responsible for carrying most venous blood back to the heart?
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What is the primary function of the epiglottis during swallowing?
What is the primary function of the epiglottis during swallowing?
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Which cartilages are paired in the structure of the larynx?
Which cartilages are paired in the structure of the larynx?
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How does the pitch of voice primarily get determined?
How does the pitch of voice primarily get determined?
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What role do vestibular folds play in normal physiology?
What role do vestibular folds play in normal physiology?
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Which tissue type primarily makes up the tunica mucosa of the trachea?
Which tissue type primarily makes up the tunica mucosa of the trachea?
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What structure marks the point where the trachea bifurcates into bronchi?
What structure marks the point where the trachea bifurcates into bronchi?
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Which of the following statements about vocal folds is incorrect?
Which of the following statements about vocal folds is incorrect?
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In what way do the vocal folds function during the Valsalva maneuver?
In what way do the vocal folds function during the Valsalva maneuver?
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Which of the following statements is true regarding sound production?
Which of the following statements is true regarding sound production?
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What type of cartilage is found in the epiglottis?
What type of cartilage is found in the epiglottis?
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Which part of the anatomy aids in the stabilization of the trunk during heavy lifting?
Which part of the anatomy aids in the stabilization of the trunk during heavy lifting?
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Which layer of the trachea wall contains seromucous glands?
Which layer of the trachea wall contains seromucous glands?
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What determines the loudness of sound produced?
What determines the loudness of sound produced?
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What is the primary role of the trachealis muscle?
What is the primary role of the trachealis muscle?
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What is the primary function of the diaphragm in the respiratory system?
What is the primary function of the diaphragm in the respiratory system?
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Which structure is primarily involved in the external respiratory process?
Which structure is primarily involved in the external respiratory process?
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Which part of the respiratory system is responsible for filtering coarse particles from inspired air?
Which part of the respiratory system is responsible for filtering coarse particles from inspired air?
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Which muscle group assists the diaphragm during the process of ventilation?
Which muscle group assists the diaphragm during the process of ventilation?
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What is the main role of the respiratory mucosa in the nasal cavity?
What is the main role of the respiratory mucosa in the nasal cavity?
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What are the three anatomical regions of the pharynx?
What are the three anatomical regions of the pharynx?
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Which of the following structures is NOT a part of the conducting zone of the respiratory system?
Which of the following structures is NOT a part of the conducting zone of the respiratory system?
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What is a key feature of the respiratory zone?
What is a key feature of the respiratory zone?
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Which area of the respiratory system is primarily involved in the exchange of gases between blood and body tissues?
Which area of the respiratory system is primarily involved in the exchange of gases between blood and body tissues?
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What function do the nasal conchae serve during respiration?
What function do the nasal conchae serve during respiration?
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Which structure serves as the passageway for both air and food in the respiratory system?
Which structure serves as the passageway for both air and food in the respiratory system?
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What is the primary role of the external nose in the respiratory system?
What is the primary role of the external nose in the respiratory system?
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Which mucosal secretion helps protect the respiratory system from pathogens?
Which mucosal secretion helps protect the respiratory system from pathogens?
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What happens to oxygen as it moves from the lungs into the bloodstream?
What happens to oxygen as it moves from the lungs into the bloodstream?
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Study Notes
Respiratory System Overview
- Respiration involves both the respiratory and circulatory systems
- Four processes supply the body with oxygen (O₂) and dispose of carbon dioxide (CO₂):
- Pulmonary ventilation (breathing): movement of air into and out of the lungs
- External respiration: O₂ and CO₂ exchange between the lungs and the blood
- Transport: O₂ and CO₂ in the blood
- Internal respiration: O₂ and CO₂ exchange between systemic blood vessels and tissues
- Cellular respiration: Oxygen (O₂) is used by cells in converting glucose to cellular energy (ATP); carbon dioxide (CO₂) is a waste product
- The body's cells die if either the respiratory or cardiovascular system fails
Respiratory System: Functional Anatomy
- Major organs:
- Nose, nasal cavity, and paranasal sinuses
- Pharynx
- Larynx
- Trachea
- Bronchi and their branches
- Lungs and alveoli
- Respiratory zone: site of gas exchange (microscopic structures: respiratory bronchioles, alveolar ducts, and alveoli)
- Conducting zone: conduits to gas exchange sites (includes all other respiratory structures)
- Respiratory muscles: diaphragm and other muscles that promote ventilation (intercostal muscles, etc.)
The Nose
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Functions:
- Provides an airway for respiration
- Moistens and warms entering air
- Filters and cleans inspired air
- Serves as a resonating chamber for speech
- Houses olfactory receptors
-
Regions:
- External nose: root, bridge, dorsum nasi, and apex
- Philtrum: a shallow vertical groove inferior to the apex
- Nostrils (nares): bounded laterally by the alae
- Skeletal Framework: frontal bone, nasal bone, septal cartilage, maxillary bone (frontal process), lateral process of septal cartilage, minor alar cartilages, dense fibrous connective tissue, major alar cartilages
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Nasal Cavity:
- Divided by a midline nasal septum
- Posterior nasal apertures (choanae) open into the nasal pharynx
- Roof: ethmoid and sphenoid bones
- Floor: hard and soft palates
-
Nasal Cavity Structures:
- Vestibule: nasal cavity superior to the nostrils (vibrissae filter coarse particles from inspired air)
- Olfactory mucosa: lines the superior nasal cavity (contains smell receptors)
- Respiratory mucosa: pseudostratified ciliated columnar epithelium (mucous and serous secretions contain lysozyme and defensins; cilia move contaminated mucus posteriorly to throat; inspired air is warmed by plexuses of capillaries and veins; sensory nerve endings trigger sneezing)
- Superior, middle, and inferior nasal conchae: protrude from the lateral walls, increase mucosal area, and enhance air turbulence
- Functions of nasal mucosa and conchae: during inhalation, filter, heat, and moisten air; during exhalation, reclaim heat and moisture
- Paranasal Sinuses: in frontal, sphenoid, ethmoid, and maxillary bones; act as resonance chambers for speech, warm and moisten incoming air, and lighten facial bones
Pharynx
- Muscular tube connecting the nasal cavity and mouth superiorly and the larynx and esophagus inferiorly
- Extends from base of skull to the sixth cervical vertebra
- Divided into three regions:
- Nasopharynx
- Oropharynx
- Laryngopharynx
- Nasopharynx: air passageway posterior to the nasal cavity, pseudostratified columnar epithelium, soft palate and uvula close nasopharynx during swallowing, pharyngeal tonsil (adenoids) on posterior wall, pharyngotympanic (auditory) tubes open into the lateral walls
- Oropharynx: passageway for food and air from the level of the soft palate to the epiglottis, stratified squamous epithelium, isthmus of the fauces opening to the oral cavity, palatine tonsils in the lateral walls of fauces, lingual tonsil on the posterior surface of the tongue
- Laryngopharynx: passageway for food and air posterior to the upright epiglottis, extends to the larynx where the respiratory and digestive pathways diverge, continuous with the esophagus
Larynx
- Attaches to hyoid bone and opens into laryngopharynx
- Continuous with trachea
-
Functions:
- Provides a patent airway
- Switching mechanism to route air and food into proper channels
- Voice production
- Cartilages: hyaline cartilage except for epiglottis, thyroid cartilage (laryngeal prominence, Adam's apple), ring-shaped cricoid cartilage, paired arytenoid, cuneiform, and corniculate cartilages
- Epiglottis: elastic cartilage, covers the laryngeal inlet during swallowing; vocal ligaments attach arytenoid cartilages to thyroid cartilage, contain elastic fibers, form core of vocal folds, opening is glottis, folds vibrate to produce sound as air rushes from lungs
- Vestibular folds (false vocal cords): superior to vocal folds, no sound production, help close glottis during swallowing
Trachea
- Windpipe: connects larynx to mediastinum
- Wall composed of three layers:
- Mucosa: ciliated pseudostratified epithelium with goblet cells
- Submucosa: connective tissue with seromucous glands
- Adventitia: outermost layer made of connective tissue that encases the C-shaped rings of hyaline cartilage
- Trachealis muscle: connects posterior parts of cartilage rings, contracts during coughing to expel mucus
- Carina: last tracheal cartilage, point where trachea branches into two bronchi
Bronchi and Subdivisions
- Air passages undergo 23 orders of branching (branching pattern called the bronchial or respiratory tree)
- Each bronchus then branches successively into lobar (secondary) and segmental (tertiary) bronchi; each lobar bronchus supplies one lobe
- Bronchioles are less than 1 mm in diameter; terminal bronchioles are the smallest, less than 0.5 mm in diameter
- In the conducting zone, cartilage rings give way to plates; cartilage is absent from bronchioles; epithelium changes from pseudostratified columnar to cuboidal; relative amount of smooth muscle increases
Lungs and Respiratory Zone
- Lungs occupy all of the thoracic cavity except the mediastinum; each lung has an apex (superior tip) and base (inferior surface that rests on the diaphragm); lung hilum (on mediastinal surface) is the site of attachment of blood vessels, bronchi, lymphatic vessels, and nerves; cardiac notch of the left lung accommodates the heart ; lobes separated into right lung (3 lobes, oblique and horizontal fissures) and left lung (2 lobes, oblique fissure)
- Bronchopulmonary segments: smallest subdivisions, divided by bronchioles and their branches
- Respiratory bronchioles, alveolar ducts, and alveolar sacs (clusters of alveoli) are the main site of gas exchange; ~300 million alveoli
- Alveoli (sacs): surrounded by fine elastic fibers, contain open pores; allow air pressure throughout the lung to be equalized; house alveolar macrophages to keep alveolar surfaces sterile
- Respiratory membrane: ~0.5-µm-thick air–blood barrier, alveolar and capillary walls with fused basement membranes, single layer of squamous epithelium (type I cells), scattered type II cuboidal cells secrete surfactant and antimicrobial proteins
Blood Supply
- Pulmonary circulation (low pressure, high volume): Pulmonary arteries deliver systemic venous blood; branch profusely, along with bronchi, to feed into pulmonary capillary networks; pulmonary veins carry oxygenated blood from respiratory zones to the heart
- Systemic circulation (high pressure, low volume): Bronchial arteries provide oxygenated blood to lung tissue; arise from the aorta and enter the lungs at the hilum, supply all lung tissue except the alveoli; bronchial veins anastomose with pulmonary veins; pulmonary veins carry most venous blood back to the heart
Pleurae
- Thin, double-layered serosa; parietal pleura on thoracic wall and superior face of diaphragm; visceral pleura on external lung surface; pleural fluid fills slitlike pleural cavity; provides lubrication and surface tension
Mechanics of Breathing
- Pulmonary ventilation consists of two phases: inspiration and expiration.
- Inspiration: Volume of thoracic cavity increases, internal gas pressure decreases, diaphragm flattens, and intercostal muscles contract (raises ribs); deep inspiration requires additional muscles (scalenes, sternocleidomastoid, pectoralis minor, erector spinae)
- Expiration: Quiet process—inspiratory muscles relax, thoracic cavity volume decreases, elastic lungs recoil reducing intrapulmonary volume, and intrapulmonary pressure rises; forced expiration is an active process using abdominal and internal intercostal muscles.
Physical Factors Influencing Pulmonary Ventilation
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Airway resistance: Friction is the major nonelastic source of resistance; relationship between flow, pressure, and resistance is: F = ΔP/R;
- Gas flow changes inversely with resistance; resistance is usually insignificant in large airways
- Resistance disappears at terminal bronchioles where diffusion drives gas movement
- As airway resistance rises, breathing movements become more strenuous
- Severely constricting bronchioles can prevent life-sustaining ventilation
- Epinephrine dilates bronchioles and reduces air resistance
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Alveolar surface tension: Surface tension attracts liquid molecules to one another, resists any force that increases the surface area of the liquid,
- Surfactant (detergent-like lipid and protein complex produced by type II alveolar cells) reduces alveolar surface tension, and discourages alveolar collapse
- Insufficient surfactant quantity in premature infants causes infant respiratory distress syndrome
- Lung compliance: A measure of the change in lung volume that occurs with a given change in transpulmonary pressure; normally high because of distensibility of lung tissue and alveolar surface tension; diminished by nonelastic scar tissue, reduced production of surfactant, and decreased flexibility of thoracic cage; Homeostatic imbalances that reduce compliance include deformities of thorax, ossification of costal cartilage, and paralysis of intercostal muscles
Applying Knowledge
- The right bronchus is the most lethal site for obstruction by a foreign body because it is wider, shorter, and more vertical than the left.
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Description
Explore the essential functions of the respiratory system, including oxygen and carbon dioxide exchange. Delve into the major organs involved in respiration, such as the lungs and trachea, and learn about cellular respiration processes. This quiz provides a comprehensive look at how the respiratory and circulatory systems work together to sustain life.
