lung anatomy

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following statements accurately describes the parasympathetic innervation of the lungs?

Parasympathetic fibers are supplied by the phrenic nerve.

Parasympathetic fibers are supplied by branches of the vagus nerve and cause bronchoconstriction and bronchial gland secretion. (correct)

Parasympathetic innervation causes bronchodilation and inhibits bronchial gland secretion.

Parasympathetic innervation is primarily controlled by epinephrine from the adrenal gland.

What is the primary function of the conducting bronchioles in the bronchial tree?

Filtering air.

Air transport without gas exchange. (correct)

Gas exchange.

Warming and humidifying air.

Which of the following structures is NOT a part of the bronchial tree?

Trachea

Tertiary bronchi

Secondary bronchi

Alveoli (correct)

What is the primary source of oxygenated blood supply to the bronchial tree?

Bronchial circulation. (D) Signup and view all the answers

Which of the following structures connects the parietal and visceral pleura?

Pulmonary ligament (B) Signup and view all the answers

Which of the following describes the path of lymph drainage from the right lung?

Pulmonary nodes -> bronchopulmonary nodes -> tracheobronchial nodes -> paratracheal nodes -> right lymphatic duct. (D) Signup and view all the answers

Which of the following is responsible for bronchodilation?

Sympathetic nervous system. (D) Signup and view all the answers

Which of the following statements accurately describes the blood flow through the pulmonary circulation?

Deoxygenated blood flows from the heart to the lungs, and oxygenated blood flows back to the heart from the lungs. (D) Signup and view all the answers

Which of the following structures is responsible for preventing food or fluid from entering the air passage during swallowing?

Epiglottis (B) Signup and view all the answers

What type of epithelium is present in the nasopharynx?

Respiratory epithelium (C) Signup and view all the answers

Which of the following cells in the olfactory epithelium act as stem cells for olfactory neurons and supporting cells?

Basal cells (C) Signup and view all the answers

Which of the following structures is responsible for sound production?

Vocal cords (D) Signup and view all the answers

What type of cartilage reinforces the rigid wall of the larynx?

Both hyaline and elastic cartilage (D) Signup and view all the answers

What is the function of the cilia in the olfactory epithelium?

To provide a large surface for chemoreceptors (B) Signup and view all the answers

What is the primary developmental abnormality that leads to Esophageal Atresia?

Failure of the tracheoesophageal septum to completely separate the trachea and esophagus. (B) Signup and view all the answers

Where do the axons from olfactory neurons synapse?

Olfactory bulb (A) Signup and view all the answers

In the context of lung development, what is the role of the pericardioperitoneal canals?

They serve as initial narrow spaces for the lungs to grow into. (C) Signup and view all the answers

What is the function of the supporting cells in the olfactory epithelium?

Their function is not well understood (D) Signup and view all the answers

What is the term used to describe the connection between the trachea and esophagus that can occur due to developmental abnormalities?

Tracheoesophageal fistula (C) Signup and view all the answers

Which of the following is NOT a direct consequence of the abnormal development of the tracheoesophageal septum?

Formation of the primary bronchial buds. (D) Signup and view all the answers

During which developmental stage do the primary bronchial buds form?

Week 5 (B) Signup and view all the answers

How many tertiary bronchi are typically formed in the right lung?

10 (C) Signup and view all the answers

What is the name given to the space between the parietal and visceral pleura?

Pleural cavity (B) Signup and view all the answers

What happens to the mesoderm covering the outside of the developing lung?

It develops into the visceral pleura. (D) Signup and view all the answers

What is the primary function of the pleural fluid?

To lubricate and facilitate gliding movement of the lungs during breathing (B) Signup and view all the answers

What happens when air enters the pleural space?

The lungs collapse (D) Signup and view all the answers

Which of the following is NOT a surface of the lung?

Posterior (B) Signup and view all the answers

What is the function of the horizontal fissure in the right lung?

To separate the superior and middle lobes (C) Signup and view all the answers

Which structure is responsible for connecting the lung to the cardiovascular system?

Hilum of the lung (D) Signup and view all the answers

What causes the pleural pressure to be slightly less than atmospheric pressure?

Opposing elastic forces of the chest wall and lung (B) Signup and view all the answers

What is the name of the recess where pleural fluid accumulates during quiet breathing?

Costo-diaphragmatic recess (B) Signup and view all the answers

What is the main difference between the right and left lungs?

The right lung has three lobes, while the left lung has two. (D) Signup and view all the answers

Which of the following describes the primary bronchus on the right side?

It is shorter, wider, and more vertical than the left primary bronchus. (A) Signup and view all the answers

Which of the following vessels arches over the right primary bronchus?

Azygos vein (B) Signup and view all the answers

What is the carina?

The point where the trachea bifurcates into the primary bronchi (A) Signup and view all the answers

What is the primary function of the trachealis muscle?

To prevent the trachea from collapsing during exhalation (A) Signup and view all the answers

Which of the following is true about bronchopulmonary segments?

They are supplied by a tertiary (segmental) bronchus, pulmonary artery, and vein. (B) Signup and view all the answers

What is the role of the nasal septum in the nasal cavities?

To divide the nasal cavities into two distinct chambers (B) Signup and view all the answers

If a foreign object is aspirated, where is it most likely to lodge?

Right primary bronchus (C) Signup and view all the answers

What is the correct sequence for the divisions of the bronchial tree, from the trachea to the alveoli?

Trachea - primary bronchi - secondary bronchi - tertiary bronchi - bronchioles - alveolar sacs (A) Signup and view all the answers

What is the primary function of the reticular fibers found within the lamina propria of alveolar sacs?

To provide structural support for the alveoli and prevent their collapse (A) Signup and view all the answers

Which type of cell is responsible for the production of surfactant?

Type II pneumocytes (D) Signup and view all the answers

What is the significance of the rich capillary network found in the interalveolar septa?

To provide a large surface area for gas exchange between the alveoli and the blood (C) Signup and view all the answers

Which of the following correctly describes the role of Boyle's Law in the process of inspiration?

As the volume of the thoracic cavity increases, the pressure within the lungs decreases, causing air to flow in (B) Signup and view all the answers

What is the primary mechanism responsible for quiet expiration?

Passive recoil of the elastic lung tissue (B) Signup and view all the answers

Which of the following best describes the role of the type I pneumocytes in gas exchange?

They form a thin, continuous epithelial lining that facilitates gas diffusion (A) Signup and view all the answers

How does the presence of tight junctions between type I pneumocytes contribute to gas exchange?

They allow for the diffusion of gases across the respiratory membrane without leakage (C) Signup and view all the answers

Which of the following correctly describes the function of dust cells in the alveoli?

They phagocytose foreign particles and cellular debris (D) Signup and view all the answers

Study Notes

Lung Anatomy

Learning Outcomes: Describe embryological development of the respiratory system, relate lung development to tracheoesophageal fistula & IRDS, identify surface anatomical landmarks of the pleurae, describe the structure of thoracic wall components (highlighting ventilation and chest wall compliance), describe anatomical landmarks, blood supply, lymphatic drainage, and innervation of lungs, identify structures and functions of upper and lower airways, and describe the histology of olfactory and respiratory epithelium.
Pre-Assessment Question 1: During embryological development, the foregut gives rise to the lungs.
Pre-Assessment Question 2: The lungs are located within the pleural body cavity.
The Beginning: A bilaminar disc (epiblast, hypoblast) transforms into a trilaminar disc (ectoderm, mesoderm, endoderm) through gastrulation, where epiblast cells migrate towards the primitive streak and differentiate into different layers.
Lateral Folding: The amniotic cavity, surface ectoderm, visceral mesoderm, parietal mesoderm, connection between the gut & yolk sac, and embryonic body cavity are involved in lateral folding.
Cranio-caudal Folding: The oropharyngeal membrane, cloacal membrane, lung bud, liver bud, heart tube, remnant of the oropharyngeal membrane, vitelline duct, and allantois are parts of cranio-caudal folding.
Lateral Plate Mesoderm: The lateral plate mesoderm splits into parietal (somatic) and visceral (splanchnic) layers. Endoderm forms epithelial linings and glands, while splanchnic layer produces muscles, cartilage, and connective tissue.
Main Components: The main components of the respiratory system are the lungs, trachea, larynx, and pleura.
Formation of the Lung Buds: At 4 weeks, respiratory diverticulum (lung buds) appear on the ventral wall of the foregut. Development depends on retinoic acid and TBX4 transcription factor. Endodermal origin forms the internal lining of the larynx, trachea, bronchi, and lungs. Splanchnic mesoderm origin forms cartilaginous, muscular, and connective tissue of the trachea and lungs.
Lung Bud & Foregut Connections: As the lung bud expands, tracheoesophageal ridges develop, then fuse to form the tracheoesophageal septum. Days 26 to 28 see the first bifurcation of lung buds, creating right and left primary bronchial buds.
Esophageal Atresia & Tracheoesophageal Fistula:
Esophageal atresia is a condition where the proximal esophagus does not connect with the distal esophagus.
Tracheoesophageal fistula is a connection (fistula) between the trachea and the esophagus, potentially due to abnormal development in utero.
Case Study: A newborn struggling to breathe and unable to swallow might have esophageal atresia or tracheoesophageal fistula.
Trachea, Bronchi, Lungs: The fifth week sees enlargement of each primary bronchial bud. The right primary bronchus forms three secondary bronchi; the left forms two.
Remember Primitive Body Cavities: Lung growth into the body cavity begins with narrow pericardioperitoneal canals. Pleuroperitoneal and pleuropericardial folds separate the channels from peritoneal and pericardial cavities, forming primitive pleural cavities. Mesoderm develops into visceral pleura, and somatic mesoderm becomes parietal pleura. The space between them is the pleural cavity.
Further Development: Secondary bronchi repeatedly divide, creating 10 tertiary (segmental) bronchi on the right lung and 8 on the left. These form bronchopulmonary segments in the adult lung. By week 24, around 17 rounds of subdivisions have occurred, and an additional six occur postnatally.
Maturation of the Lungs: The four stages of lung maturation include: (1) pseudoglandular (5-16 weeks), (2) canalicular (16-26 weeks), (3) terminal sac (26 weeks-birth), and (4) alveolar (36 weeks-8 years).
What's Next? Bronchioles divide into smaller canals and vascular supply increases up to the 7th month. Terminal bronchioles divide into respiratory bronchioles and further into alveolar ducts ending in alveoli.
Type I & Type II Alveolar Epithelial Cells: Type I alveolar epithelial lining thin and surrounded by blood capillaries. Type II cells develop by week 24, producing surfactant, which lowers surface tension in the lungs.
Fetal Breathing Movements: Fetal breathing begins before birth to prepare the lungs and stimulate their development conditioning respiratory muscles. Lung fluid is resorbed at birth. Surfactant coats alveoli, preventing collapse during the first breath.
Infant Respiratory Distress Syndrome (IRDS): Formerly hyaline membrane disease, IRDS results from insufficient surfactant, causing high surface tension and alveolar collapse during exhalation. It's a common cause of infant death, accounting for around 20%.
Larynx: Lines with endoderm; cartilages & muscles from fourth/sixth pharyngeal arches develop into thyroid, cricoid, and arytenoid cartilages. Rapid proliferation changes laryngeal orifice shape.
Larynx (cont.): As cartilages are formed, laryngeal epithelium occludes the lumen. Subsequent vacuolation & recanalization produces lateral recesses (laryngeal ventricles). Tissue folds form false & true vocal cords. Laryngeal muscles innervated by vagus nerve (CN X).
Landmarking Pleurae: Visceral pleura adheres to the lung; parietal pleura lines the internal thoracic cavity; together they form a pleural sac surrounding each lung.
Parietal Pleura: Mediastinal parietal pleura lines the lateral surface of the mediastinum; costal lines the ribs' internal surface; diaphragmatic lines the superior diaphragm surface; cervical/cupula extends above rib 1 to the neck root. Innervated by general sensory neurons (sensitive to pain.) Intercostal nerves innervate the peripheral portion of the diaphragm and ribs, while phrenic nerves innervate the central portion of the diaphragm and mediastinum.
Visceral Pleura: Follows lung lobe contours, contiguous with parietal at hilum, producing and reabsorbing pleural fluid with assistance from the parietal pleura's lymphatics. Innervated by visceral sensory neurons (insensitive to pain; innervated by the autonomic vagus nerve (CN X)) and has simple squamous mesothelium.
Pleural Space: Located between parietal & visceral pleura. Pleural fluid lubricates & enables gliding during breathing movements. Surface tension keeps parietal & visceral pleura in contact and resists lung collapse. Pleural pressure slightly lower than atmospheric pressure (negative pressure) and opposes elastic forces of the chest wall & the lung.
Pneumothorax: Air enters pleural space, often due to chest trauma, causing a collapsed lung and breaks the parietal/visceral pleura coupling.
Pleural Recesses: Lungs don't fill the entire pleural sac during quiet breathing. These incomplete-filling areas are called pleural recesses. Costodiaphragmatic recesses and costomediastinal recesses allow lung expansion during deep breaths. A medical professional would find the costodiaphragmatic recess during a hemothorax.
Back to the Lungs: Lungs are pyramid-shaped, featuring an apex and base. They have costal, diaphragmatic, and mediastinal surfaces. Borders include anterior, posterior, and inferior borders.
Lobes of the Lung: Right Lung: three lobes (superior, middle, inferior); two fissures (horizontal, oblique). Left Lung: two lobes (superior, inferior); one fissure (oblique).
Hilum of the Lung: Location where blood vessels, airways, lymphatics, and nerves enter/leave the lungs. Connects lungs to cardiovascular system. Parietal and visceral pleura meet at the pulmonary ligament.
Blood Supply to the Lung:
Bronchial Circulation: Supplies oxygenated blood to the bronchial tree by branches of the aorta, and bronchial veins.
Pulmonary Circulation: Circulates deoxygenated blood to the lungs and oxygenated blood back to the heart.
Lymphatic Drainage of the Lung: Lymphatic vessels define lung lobules and collect lymph from lung lobes to drain via pulmonary and bronchopulmonary (hilar) nodes, to tracheobronchial (carinal) nodes and paratracheal nodes and then enter systemic circulation via the right lymphatic duct (right lung) or thoracic duct (left lung).
Innervation of the Lungs: Pulmonary plexus surrounds the trachea and bronchial tree and innervates them with both parasympathetic and sympathetic fibers. Parasympathetic fibers innervated by vagus nerve (CN X) cause bronchoconstriction and bronchial gland secretion. Sympathetic fibers (T1-T4 & cervical ganglia) cause bronchodilation and inhibit gland secretion. Adrenal gland's epinephrine is also a key controller of sympathetic function.
Bronchial Tree: Listing of structures: the trachea, primary bronchi, secondary bronchi, tertiary bronchi, conducting bronchioles, terminal bronchioles, respiratory bronchioles, and alveoli.
Bronchial Tree (cont.): Conducting airways; the trachea begins at the cricoid cartilage and splits into right/left primary bronchi (T4-T5 level). Walls have C-shaped hyaline cartilage rings, open posteriorly by trachealis muscle. Carina is ridge at primary bronchi bifurcation.
Bronchial Tree (cont.): Right primary bronchus divides into superior, middle, and inferior secondary bronchi, a shorter, wider, more vertical branch that arches over the right SVC. Left primary bronchus divides into superior and inferior secondary bronchi. Left pulmonary artery arches over the bronchus. Tertiary bronchi branch into bronchioles and terminate in alveolar sacs.
Bronchopulmonary Segments: Each lung region with a tertiary bronchus is a bronchopulmonary segment—anatomical, functional, and surgical units.
Respiratory Tracts: Anatomical features & components of the upper (nasal cavity, pharynx, larynx) and lower (trachea, bronchi, bronchioles, alveoli, pleura) respiratory tracts.
Nasal Cavities: Two chambers separated by nasal septum, lined with mucosa and conchae. Blood flow warms and humidifies air; mucus traps particles; immunoglobulin A inactivates microorganisms. Upper, middle, and inferior conchae have respiratory epithelium; olfactory epithelium present in superior conchae and nasal roof. External vestibule contains sweat glands, sebaceous glands, and vibrissae (nose hairs).
Respiratory Epithelium: Pseudostratified columnar cells with cilia and goblet cells. Ciliated cells move mucus; goblet cells secrete mucus; brush cells—sensory receptors. Small granule cells (diffuse neuroendocrine system) and basal cells (stem cells).
Olfactory Epithelium: Lines superior conchae; olfactory neurons are bipolar, have nuclei near middle. Dendrites/cilia contact aqueous layer, provide surface area for chemoreceptors. Respond to odoriferous substances to produce action potentials along axons traveling through cribriform plate of ethmoid bone to synapse in olfactory bulb. Supporting cells (tall columnar shaped; nuclei concentrated at base; role unknown; express abundant ion channels) and basal cells (small, spherical; basal lamina; stem cells).
Pharynx:
Nasopharynx: Respiratory epithelium, medial pharyngeal tonsil (adenoids), and openings for auditory tubes.
Oropharynx: Nonkeratinized stratified squamous epithelium, palatine and lingual tonsils.
Laryngopharynx: Nonkeratinized stratified squamous epithelium.
Larynx: Rigid wall reinforced by hyaline cartilage (thyroid, cricoid, arytenoid); elastic cartilages (epiglottis, cuneiform, corniculate). Skeletal muscles controlled movements for sound; epiglottis structure prevents swallowed food from entering the airway. Lingual surface is stratified squamous; laryngeal surface transitions to respiratory epithelium.
Larynx (cont.):
Vestibule of Larynx: Mucosa projects into the lumen below the epiglottis.
Upper pair of Immovable vestibular folds (covered with respiratory epithelium) - seromucous glands/lymphoid nodules
Lower pair: Vocal folds (cords) used for phonation (nonkeratinized stratified squamous epithelium; Supported by vocal ligament and vocalis m. that moves the cords).
Trachea: Lined with respiratory mucosa and lamina propria. Walls strengthened by C-shaped hyaline cartilage rings to keep lumen open; trachealis connects open ends of rings on posterior surface.
Bronchi: Primary bronchi maintain cartilage rings encircling lumen. Bronchioles lose rings, develop smooth muscle and mucous glands.
Bronchioles: Lacks mucosal glands and cartilage. Increasingly smaller pseudostratified columnar epithelium (larger bronchioles); Ciliated simple columnar or simple cuboidal epithelium in terminal bronchioles initiating mucociliary apparatus or escalator to clear debris and mucus.
Terminal Bronchioles: Lined with cuboidal epithelium (club cells—nonciliated, dome-shaped); granules/secretory granules present—surfactant lipoproteins and mucins, detoxification of inhaled xenobiotics by via SER; antimicrobial peptides, cytokines. Chemosensory brush cells, DNES small granule cells, and stem cells present. Elastic fibers and smooth muscle in lamina propria.
Respiratory Bronchioles: Each terminal bronchiole subdivides into 2 or more respiratory bronchioles. Include saclike alveoli. Smooth muscle & elastic connective tissues in propria. Epithelium consists of club cells and simple squamous at alveolar openings extend into alveoli.
Alveolar Ducts & Sacs: Alveolar ducts branch from respiratory bronchioles into alveoli w/ extremely attenuated squamous cells. Lamina propria surrounds openings; elastic and collagen fibers support. Alveolar sacs contain web-like elastic/reticular fibers surrounding openings and alveoli.
Alveoli: Site of gas exchange. Respiratory membrane has thin Type I epithelial cells with fused basal laminae and capillary endothelial cells. Elastic and reticular fibers in septa allow expansion/contraction (and prevent collapse). Abundant capillaries surrounding alveoli.
Alveolar Cells:
Type I pneumocytes: Thin epithelial cells, desmosomes/tight junctions.
Type II pneumocytes: Cuboidal cells, release surfactant in lamellar bodies. Site of SARS-CoV-2 attachment. Dust cells: Phagocytes of erythrocytes and debris.
Ventilation:
Boyle's Law: Volume and pressure of gas in a container are inversely related.
Inspiration: Diaphragm flattens, external intercostals contract, increasing thoracic volume, decreasing pressure, creating vacuum, and air moving into lungs (inspiration ends when thoracic volume stops increasing).
Quiet Expiration: Passive process - inspiratory muscles relax, diaphragm ascends, rib cage descends, elastic lung tissue recoils.
Forced Expiration: Active process - expiratory muscles contract (external & internal obliques, transverse, & rectus abdominis) increasing intra-abdominal pressure, forcing abdominal organs up against diaphragm/ribcage to depress it.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the anatomy and functions of the respiratory system with this quiz. Explore questions covering the bronchial tree, pleura, and associated structures. Perfect for students studying anatomy or respiratory physiology.