Respiratory Tract

Question 1

What forms can epithelium come in?

Answer 1

Simple (single layered)
Stratified (multiple layers)

Squamous (scale like)
Cuboidal (cube like)
Columnar (Column like)

Pseudostratified (simple appearing to look stratified)

Question 2

List the upper and lower components of the respiratory system (conducting portion)

Answer 2

Upper:
Nasal cavity
Pharynx
Larynx

Lower:
Trachea
Bronchi
Bronchioles
Terminal bronchioles

Question 3

List the three components of the respiratory portion of the respiratory tract

Answer 3

Respiratory bronchioles
Alveolar ducts
Alveolar sacs and alveoli

Question 4

Outline the function of the lungs

Answer 4

Olfaction (environmenal smelling)
Phonation (vocal folds)
Conduction and conditioning of air (warmth, air transport and clearance)
Gaseous exchange
Endocrine (hormones)
Immune functions (macrophages, lymphoid tissue)

Question 5

Outline features of the nasal cavity

Answer 5

Vestibule
Respiratory region
Olfactory region

Question 6

What is the vestibule?

Answer 6

• A cartilage framework
• Stratified squamous epithelium
• Short firm hairs
• Sweat and sebaceous glands

Question 7

What is the respiratory region?

Answer 7

• Respiratory epithelium
• Lamina propria
• Has turbinates to increase SA of resp. mucosa

Question 8

What is the olfactory region?

Answer 8

• Roof of nasal cavity
• Lined by pseudostratified columnar epithelium, 4 cell types

Question 9

What illnesses affect the nasal cavity?

Answer 9

Allergic reactions or vital infections

Can lead to Rhinitis/coryza (inflammation of nasal mucous membrane - capillaries near surface become engorded, restricts breathing)

Question 10

What glands are located at the nasal olfactory region?

Answer 10

Serous olfactory (Bowman’s) glands

Produce a serous fluid, bathes cilia and serves as a solvent to dissolve odor molecules so olfactory cells can detect them

Question 11

What cell types are in the olfactory epithelium?

Answer 11

Olfactory receptor cells
Supportive
Brush cells
Basal cells

Question 12

What cells are in the nasal respiratory epithelium?

Answer 12

Ciliated columnar cells
Mucus cells
Brush cells
Small granule
Basal cells

Question 13

Outline the ciliated columnar cell type

Answer 13

• Columnar, extend to surface
• 250 cilia
• Sweeping motion to expel particles trapped in mucus

Question 14

Outline the mucus cell type

Answer 14

• Short, blunt microvilli
• Secretes mucin granules to form a protective barrier
• Increased in smokers/chronic inflammation

Question 15

Outline the brush cell type

Answer 15

• Columnar, extend to the apical surface
• Short microvilli
• Synapse with afferent nerves gives sensory function
• Sensory receptors allow transduction of sensation

Question 16

Outline the small granule cell type

Answer 16

• Most numerous at bifurcation of primary bronchi
• Basal granules
• AKA Kulchitsky
• Primary cells affected in small cell carcinoma of the lung

Question 17

Outline the basal cell type

Answer 17

• Near basement membrane
• Stem cells
• Regenerate all other cell types

Question 18

Outline Kartagener syndrome

Answer 18

• Immotile cilia syndrome
• Genetic disorder (autosomal recessive)
• Mutation in gene coding for ciliary proteins
• Results un situs inversus, recurrent sinus, pulmonary infections, sterility

Question 19

Outline the larynx

Answer 19

• Tubular region
• Skeletal framework contains plates of hyaline cartilage
• Functions include sir conduction, phonation (speech sounds)

Question 20

Outline the trachea

Answer 20

Contains:
- Mucosa (Resp. epith, elastic fibres, Lamina propria)
- Submucosa (seromucous glands, loose connect. tissue)
- Cartilaginous layer (c-shaped hyaline, fibroelastic membrane, trachealis muscle)
- Adventitia (connective tissue)

Question 21

Outline the bronchi

Answer 21

-:Primary bronchi: structurally like trachea
- Segmental bronchi supply a bronchopulmonary segment
- Bronchi can be primary/secondary/tertiary, or extrapulmonary/intrapulmonary (surrounded by lung tissue)

Question 22

What features do the bronchi have?

Answer 22

Mucosa (Resp. epith)
Muscular layer (smooth muscle, regulate airway diameter)
Submucosa (seromucus glands)
Cartilage layer (plates in intrapul, rings in extrapul)
Adventitia (connective tissue)

Question 23

What type of cartilage is found in extrapulmonary and intrapulmonary bronchi?

Answer 23

Intrapulmonary: cartilage plates
Extrapulmonary: cartilage rings

Question 24

What does squamous metaplasia mean?

Answer 24

Noncancerous (benign) changes in squamous cells in epithelium.

E.g., smoking looses ciliated cells. Bronchitis. Squamous cell carcinoma.

Question 25

Outline the bronchioles

Answer 25

• 1mm diameter or less
• Regular (larger), terminal, respiratory types

Larger: epithelium:
- ciliated, pseudostratified columnar transitioning into simple ciliated columnar, goblet cells

Smaller: epithelium:
- Simple cuboidal with secretory club and ciliated cells, NO goblet cells, smooth muscle instead of cartilage

• Bronchial asthma = inflammatory airway disease

Question 26

Outline type I and II pneumocytes

Answer 26

Type I:
- Squamous cells line 95% of alveolar surface
- Incapable of mitosis
- Surface covered by surfactant

Type II:
- Cuboidal cells, secrete surfactant
- Found at septal junctions/cells
- Only cover 5% of alveolar surface

Question 27

How is alveolar surfucant managed

Answer 27

Regulated by cortisol, insulin, thyroxin, prolactin

Question 28

What does interalveolar septum contain?

Answer 28

Collagen fibres
Elastic fibres (for pulmonary recoil)
Continuous capillaries
Permanent and transient cells

It is the site of the air-blood barrier

Pneumonia is spread by their alveolar pores

Question 29

Give three examples of clinical conditions

Answer 29

Smoking induced metaplasia
Chronic obstructive pulmonary disease
Cystic fibrosis