Respiratory Histology (Dennis)

Question 1

What are the functions and components of the conducting portion of the respiratory tract?

Answer 1

• function: air passage that leads to sites of respiration within lungs where gas exchange occurs
• components: nasal cavity, paranasal sinuses, nasopharynx, larynx, trachea; primary, secondary, tertiary bronchi; bronchioles, terminal bronchioles

Question 2

What are the functions and components of the respiratory portion of the respiratory tract?

Answer 2

• function: locations leading to or locations where gas exchange occurs
• components: bronchioles, alveolar ducts, alveolar sacs, alveoli

Question 3

Describe the structure of respiratory epithelium:

Answer 3

• pseudostratified columnar ciliated epithelium
• lamina propria: rich, vascular network w/ complex set of capillary loops
• confined to airways of the respiratory system

Question 4

What are the cells present within respiratory epithelium?

Answer 4

• ciliated, columnar epithelial cells (70%)
• goblet cells (5-15%)
• brush cells: have short, blunt microvilli; chemosensory cells connected to sensory nerve fibers
• small granule cells: resemble basal cells but have secretory granules; endocrine cells of diffuse neuroendocrine system (DNES)
• basal cells: non-ciliated, stem cells that lie on basement membrane

Question 5

What are the 3 regions of the nasal cavities?

Answer 5

• nasal vestibule: inside the nostrils, lined by skin
• respiratory region: inferior 2/3 of nasal cavities, lined w/ respiratory mucosa
• olfactory region: located at the apex (upper 1/3), lined by specialized olfactory mucosa

Question 6

What is the function of nasal cavities in terms of temperature?

Answer 6

• adjusts temp and humidity of inspired air
• this function is enhanced by large surface are provided by turbinate bones

Question 7

What is the structure and function of paranasal sinuses?

Answer 7

• structure: air-filled spaces in bones of walls of nasal cavity, extensions of respiratory region of nasal cavity, lined by respiratory epithelium
• function: communicate w/ nasal cavities via narrow openings into respiratory mucosa; mucus prod in sinuses is swept into nasal cavities by ciliary movements

Question 8

What is the clinical relevance of paranasal sinuses?

Answer 8

• sinuses are often subject to acute infection after viral infection UR tract
• severe infections may require physical drainage

Question 9

What type of epithelium is the nasal vestibule and respiratory region of the nasal cavities composed of?

Answer 9

• nasal vestibule: keratinized stratified squamous epithelium (skin), top picture
• respiratory region (posterior to vestibule): pseudostratified columnar ciliated epithelium, bottom picture

Question 10

What is the structure and function of olfactory mucosa?

Answer 10

• covers the superior conchae bilaterally and contains receptors for sense of smell
• composed of pseudostratified ciliated columnar epithelium (10 cm2 area)
• olfactory (Bowman’s) glands: serous secretions that dissolve odorant molecules
• hallmarks: dramatically thicker and LACKS goblet cells, nonmotile cilia

Question 11

What cells are present in the olfactory mucosa?

Answer 11

• olfactory receptor neurons (ORNs): single dendritic process; specialized, nonmotile cilia w/ odorant receptors; ligand binding causes action potential
• basal cells: stem cells that replnish the mucosa
• brush cells: ciliated, columnar epithelial cells in contact w/ CN V
• sustentacular cells: provide mechanical and metabolic support to ORNs

Question 12

Answer 12

Question 13

What is the structure and function of the larynx?

Answer 13

• short passage for air between pharynx and trachea
• rigid walls reinforced by cartilage, movements involve skeletal muscle that participates in phonation:
• hyaline cartilage: thyroid, cricoid, inferior arytenoid cartilages
• elastic cartilage: epiglottis, cuneiform, corniculate, superior arytenoid cartilages

Question 14

What is the structure and function of the epiglottis?

Answer 14

• prevents swallowed food/fluid from entering the airways
• core of elastic cartilage
• lingual surface = stratified squamous epithelium
• laryngeal surface = transitions to ciliated pseudostratified columnar epithelium
• mixed mucous and serous glands are found in the lamina propria beneath the epithelium

Question 15

What are the folds and ligament of the larynx?

Answer 15

• vestibular folds: respiratory epithelium w/ seromucous glands and lymphoid nodules; superior pair, immovable
• vocal folds: nonkeratinized stratified squamous epithelium; protects abrasion and desiccation; used for phonation or sound prod
• vocal ligament: dense regular bundle of elastic CT; supports the free edge of vocal cord

Question 16

• inflammation of the larynx (viral, allergies)
• edema of lamina propria changes shape of vocal folds causes hoarseness/loss of voice

Answer 16

laryngitis

Question 17

• laryngitis in young children
• edema of laryngeal mucosa causes hoarseness and loud/harsh coughs

Answer 17

croup

Question 18

Answer 18

Question 19

Where in the respiratory tract are these tissues are present:

• epithelium:
• goblet cells:
• ciliated cells:
• glands:
• hyaline cartilage:
• smooth muscle:
• elastic fibers:

Answer 19

Where in the respiratory tract are these tissues are present:

• epithelium: pseudostratified columnar ciliated epithelium (except nasal vestibule and vocal folds)

*for the rest refer to the photo*

Question 20

What is the structure and function of the trachea?

Answer 20

• short, flexible, air tube that serves as conduit for air
• extends from larynx and divides into the main/primary bronchi
• lumen of the trachea remains open because of stacked cartilaginous rings
• trachealis m.: bundle of smooth muscle that spans the open ends of cartilage rings posteriorly

Question 21

Describe the mucosa, submucosa, and adventitia of the trachea: