Lecture 29: Pulmonary Histology

Question 1

What epithelium lines the nares?

Answer 1

Stratified squamous epithelium continuous with epidermis; nares contain sebaceous and suderiferous glands and hair follicles

Question 2

What is respiratory epithelium?

Answer 2

Pesudostratified ciliated columnar epithelium

Question 3

Olfactory epithelium

Answer 3

located in nasal cavity roof; respiratory epithelium WITHOUT goblet cells; no distinct basement membrane

Question 4

Sustentacular cells

Answer 4

Support cells with pigment granules (olfactory epithelium)

Question 5

Basal cells

Answer 5

Have pigment granules; stem cells - give rise to immature olfactory cells (olfactory epithelium)

Question 6

Olfactory cells

Answer 6

Bipolar neurons; apical end projects into nasal cavity as knoblike ending w/ non-motile cilia (G-protein linked odor receptors); basal end of cell extends as unmyelinated axon bundled with other similar axons through the ethmoid plate to mitral cells located in olfactory bulb; senesce and replaced by basal cells

Question 7

Olfactory glands of Bowman

Answer 7

Located in lamina propria, secrete odorant binding protein which binds to odorant molecule in nasal cavity

Question 8

Waldeyer’s Ring

Answer 8

Ring of lymphoid tissue around nasopharynx which includes tonsils and adenoids; “portal” in back of nasopharynx that encounters airborne antigens and initiates immune response

Question 9

Lingual surface of epiglottis

Answer 9

Covered with stratified squamous epithelium; lamina propria with loose CT and elastic fibers

Question 10

Pharyngeal surface of epiglottis

Answer 10

Covered with respiratory epithelium; lamina propria with tubuloacinar seromucous glands

Question 11

False vocal cords

Answer 11

Covered with respiratory epithelium, lamina with seromucous glands

Question 12

True vocal cords

Answer 12

Covered with stratified squamous epithelium, lack seromucous glands in lamina propria

Question 13

Name all 5 tissues found in larynx

Answer 13

Respiratory epithelium, stratified squamous epithelium, hyaline cartilage, elastic cartilage, skeletal muscle

Question 14

Mucosa of trachea

Answer 14

Respiratory epithelium, thick basement membrane; Lamina propria with delicate FECT and lymphatic tissue

Question 15

Submucosa of trachea

Answer 15

Many seromucous glands

Question 16

Adventitia of trachea

Answer 16

16-20 horseshoe shaped cartilages interconnected by FECT which are closed by trachealis muscles, mixed glands and capillaries

Question 17

Bronchi

Answer 17

2 primary - one to each lung; extrapulmonary; resemble trachea except for smaller diameter and circular cartilage rings

Question 18

Secondary bronchi

Answer 18

Each primary divides into 3 on the right, 2 on the left; AKA segmental bronchi - mostly intrapulmonary; circular rings of cartilage transition into irregular plates

Question 19

What happens to histological characteristics of bronchi as they decrease in size?

Answer 19

Height of epithelium decreases, there is a decrease in cartilage and glands, and an increase in proportion of elastic fibers and smooth muscles

Question 20

Mucosa of intrapulmonary bronchi

Answer 20

Similar to trachea and extrapulmonary bronchi; mucosal folds present due to smooth muscles, elastic fibers prominent

Question 21

Submucosa of intrapulmonary bronchi

Answer 21

Characterized by loose CT and lymphatic tissue, contains mixed glands and mucous glands

Question 22

Adventitia

Answer 22

Contains hyaline cartilage plates surrounded by dense FECT

Question 23

Name some characteristics of bronchioles

Answer 23

Absence of cartilage, glands; sparse goblet cells, mostly smooth muscle; ciliated columnar to ciliated cuboidal; terminal bronchioles form 2 or more respiratory bronchioles

Question 24

Name some characteristics of respiratory bronchioles

Answer 24

Low columnar/cuboidal epithelium, cilia present only in larger respiratory bronchioles; no goblet cells, smooth muscle wall within FECT; some alveolar outpocketings as gas exchange occurs here first

Question 25

Alveolar ducts

Answer 25

continuation of respiratory bronchioles, cone-shaped and made of squamous epithelium with smooth muscle/FECT

Question 26

Alveoli

Answer 26

Several within each alveolar sac; separated by thin alveolar septa; walls composed of Type I, II alveolar cells, macrophages, contain Pores of Kohn

Question 27

Type I alveolar cells/pneumocytes

Answer 27

Less numerous than Type II, but cover largest surface area (more spread out); very thin cytoplasm, tight junctions connect with other type I cells, basal lamina may be fused with basal lamina of nearby capillaries

Question 28

Type II alveolar cells/pneumocytes

Answer 28

Cuboidal/rounded-bulge into alveolar lumen, serve as stem cells for type I and type II pneumocytes; contain numerous lamellar bodies with lecithin which is a component of surfactant; these cells can also phagocytize old surfactant

Question 29

Pores of Kohn

Answer 29

Openings between adjacent alveoli - collateral respiration

Question 30

Neuroendocrine cells

Answer 30

May be associated with sensory reception and more prevalent in infants; release catecholamines

Question 31

Clara cells

Answer 31

Found only in bronchioles; secrete protein which is a component of surfactant; number increases as ciliated columnar cells decrease; apical surface bulges into lumen of airway; abundant SER for lipid synthesis

Question 32

Dust cells/macrophages

Answer 32

derived from monocytes, phagocytize particles not trapped in mucous; connection to CHF: fluid containing hemoglobin breakdown products leak into alveolar spaces and phagocytized by dust cells - iron-containing dust cells are referred to as heart failure cells

Question 33

Blood-Air Barrier

Answer 33

Consists of: thin capillary endothelium, thin epithelium of pneumocyte, intervening basal lamina produced by both cell types; permits gas exchange but does NOT allow fluids or cells to enter alveoli