1. Vestibule
2. Olfactory segment
3. Respiraotry segment

• Stratified squamous epithelium
• Part of nose that you pick
• Epidermis and dermis
• Dermis has subaceous & sweat glands
• Vibrissae- stiff hairs that trap particles
• Nasal conchae/turbinates- 3 bones that churn air, fascilitate:
• Humidification
• Warming- extensive BV underlying nasal epith.
• Cause of common nosebleeds
• Filtration

• Covers roof of nasal cavity- senses smell
• Specialized pseudostratified columnar epithelium
• All cells make contact with basement membrane, but not all reach lumen
• 3 cell types found in olfactory segment:

1. Olfactory receptor cells- neurons

• Bipolar
• Immotile cilia (no dynein)
• Odorant receptors on surface
• Only neurons in NS that are exposed directly to external environmen

2. Supporting/sustentacular cells

• Physical and metabolic support to olfactory cells
• Yellow

3. Basal cells- stem cells for other 2

Bowman's glands/olfactory glands and ducts:

• Beneath olfactory epithelium
• Serous secreting glands
• Act as solvent to clear away odorant

Mucociliary Escalator

*Goblet cells (30%)

• Secrete mucus that blankets ciliated cells

*Ciliated columnar epith.

• ~300cilia/cell, lots of mito., to move mucus upward, carrying debris with it

Kartegener's Syndrome- immotile cilia; lack dynein

• Lots of respiratory infections- mucus promotes growth of bacteria and infection

• 3%
• Lots of microvilli on apical surface (actin)
• Afferent nerve endings on basal surfaces- considered *sensory neurons

• 30%
• Location: basement membrane, but their apical surfaces do not reach the lumen
• ***Relatively undifferentiated cells that can differentiate into:
•  Goblet cells
• Ciliated columnar
•  Brush cells

Core of elastic cartilage

Open- breath air

Closed- swallow food

3 sections

• Nasopharnx- respiratory epithelium
• Oroopharynx- stratified squamous
• Laryngeopharynx- stratified squamous

Composition

• Hyaline and elastic cartilage
• Elastic cartilage- includes epiglottis 
• No fibrocartilage

2 main functions:

• Phonation- mucosa of larynx: true vocal cords modify slit-like opening (lower) and false, immobile (upper) vocal cords
• Separated via laryngeal ventricle
• Control airway via epiglottis- elastic cartilage
• Open- air to trachea
• Closed- food to esophagus

• Vocal cords reinforced by vocal ligament- dense, regular CT
• Vocal ligament attached to vocalis muscle- assist other intrinsic laryngeal muscles to change tension of vocal cords
• Phonation- cords strongly adducted
• Longer the cords- deeper pitch of sound

True vocal ligament

• *Stratified squamous epithelium
• Vocal ligament- dense, regular CT
• Vocallis muscle- skeletal muscle regulates tension of cords

False vocal ligament

• *Respiratory epithelium (pseudostratified)
• Lamina propria with many exocrine glands
• No skeletal muscle 

Dysplasia- indicative of early neoplastic process

• expansion of immature cells with corresponding decrease in number and location of mature cells

Metaplasia- false vocal cord with patch of stratified epithelium (smokers)

• Respiratory epithelium (psedostratified)
• C-shaped hyaline cartilage rings in lamina propria
• Adacent rings connected via dense firboelastic ligament
• Continuous with perichondrium of each ring
• Open ends posteriorly toward esophagus
• Connected by bundle of smooth muscle

Decrease:

• Cartilage
• Number of glands and goblet cells
• Height of cells

Cartilagenous rings on trachea and extrapulmonary bronchi, become cartilagenous plates when enter lung, which become smaller and less numerous as the bronchi gets maller-->*bronchioles ~1mm have no cartilage

• *Do NOT contain cartilage
• *Contain Clara cells- unique to bronchioles
• As size decreases, number of ciliated cells decraese and number of Clara cells increase
• Decrease in height- ciliated columnar--> columnar or cuboidal epithelium

• Secrete a component of GAGs and surfactant
• Detoxify inhaled substances
• Lots of SER and cP450s to metabolize airborn toxins
• Divide and differentiate into to cuboidal and non-ciliated epithelial cells
• *Note: ciliated cells in resp. epith. arise from basal cells, not Clara cells

Respiratory Distress Syndrome (RDS)

• Occurs in newborns who do not produce enough sufactant (~week 26- they are able to breathe on their own)
• Leads to cyanosis and RDS
• Treatment:
• Glucocorticoids to mother and synthetic surfactant therapy
• Reduces surface tension
• Glucocorticoids stimulaties Type II penumocyte production of surfactant

1. Aleolar epithelial cells
2. Basal lamina of alveolar epithelium
3. Basal lamina of capillary endothelium
1. Basal lamina 2 and 3 often fused together
4. Endothelial cells of capillary network

Function:

• Prevent air bubbles in blood
• Barrier permeable to O₂, CO₂, and CO and other gas 

• aka Dust Cells
• Located within air space and interalveolar septum
• *Move b/t air and liquid space
• Scavenge for particulate matter

• aka Pores of Kohn
• Location: interalveolar septum
• Funciton: equalizie pressure within alveoli
• COPD-