Histology 2: Respiratory System

Question 1

Vestibule region of the nasal cavity and epithelium type present

Answer 1

Vestibule: stratified squamous epithelium w/ many stiff hairs (vibrissae) and associated sebaceous glands.

Question 2

Respiratory region of the nasal cavity and epithelium type present.

Answer 2

Respiratory segment: Ciliated pseudo stratified columnar epithelium w/ goblet cells.

Specific Cell Types: t

• Ciliated cells: tall columnar w/ motile cilia.
• Goblet cells: synthesize and secrete mucus via mercerize secretion.
• Basal cells: can differentiate into any of the other cell types
• Brush cells: short/blunt microvilli, receptor cells.
• Small granule cels: secretory and contain membrane-bound dense-core granules @ cell base.

Question 3

What comprises the Mucociliary Apparatus?

Answer 3

Ciliated cells + Goblet Cells in the respiratory region.

Question 4

Olfactory region of nasal cavity and epithelium type present

Answer 4

Olfactory cell/Bipolar Neuron:

• Dendrites:
• -have apical projections = Olfactory vesicle.
• -Cilia (non-motile) - Olfactory receptors
• Axon:
• -Olfactory nerve (CN I)

Supporting Cell/Sestentacular:

• Tall columnar, most numerous in Olfactory region
• -microvilli, apical position of nuclei
• Fx: mechanical and metabolic support of Olfactory Cells

Basal Cells:
-replacement cells, able to replace Olfactory Cells/Bipolar Neurons, method unknown

Bowman’s Glands:

• Branched tubuloalveolar glands
• serous secretion, constant flow to refresh surface

Question 5

Larynx: lining layers and cartilages present

Answer 5

Lined by respiratory epithelium and stratified squamous epithelium.

Cartilages: hyaline and elastic

Question 6

Layers of Trachea

Answer 6

Mucosa: Ciliated pseudostratified columnar epithelia.

Submucosa: Connective tissue, Seromucous glands, many lymphoid follicles (primary and secondary)

Cartilaginous layer: Hyaline cartilage and C-shaped cartilages (~20)

Trachealis muscle
Adventitia

Question 7

Structure of Bronchus:

Answer 7

Mucosa: ciliated pseudostratified columnar epithelium, lamina propria (w/ BALT)

Muscularis: smooth muscle

Submucosa: Serous glands, loose CT

Cartilaginous layer: hyaline cartilage, discontinuous plates

Adventitia

Question 8

Structure of Bronchioles

Answer 8

Walls do not contain cartilage or glands, only surface epithelia, lamina propria, smooth muscle.

Question 9

Terminal bronchiole structure

Answer 9

last portion of the CONDUCTION system for respiration.

Lined w/ simple cuboidal epithelium of two types:

• Cuboidal or low columnar: w/ cilia, help move secretions up bronchioles, more numerous
• Clara cells: specialized secretory cells, no cilia, many granules.

Question 10

Respiratory bronchioles

Answer 10

1st site of gas exchange

Large number of Clara cells
Decreasing numbers of ciliated cells distally.

Question 11

Type 1 Pneumocyte (Type 1 Aveolar Cell)

Answer 11

Flattened squamous cell, comprises 95% of alveolar surface

Joined by occluding junctions, not capable of mitosis.
Basal lamina fused w/ endothelial cells of the tight capillaries. Have occluding junctions and helps prevent fluid movement into alveolus.
Represent the air/blood barrier, primary location of gas exchange.

Question 12

Type 2 Pneumocyte (Type 2 Aveolar Cell)

Answer 12

large, rounded or cuboidal secretory cells.
Cytoplasm rich w/ granules containing surfactant.
Capable of mitosis and act as progenitors for Type 1 cells.

Question 13

Respiratory Distress Syndrome (RDS)

Answer 13

1 cause of death in developed countries during 1st month of life.

Premature infants surfactant synthesis is low and may result in alveoli collapsing on successive exhalation.

Requires exogenous surfactant to reduce risk of RDS.

Question 14

Purpose of interaveolar septa and pores:

Answer 14

helps connect neighboring alveoli, equalize air pressure and provide collateral air circulation if bronchiole is obstructed.

Question 15

Alveolar Macrophages

Answer 15

Derived from blood monocytes

Present in septal walls and alveolar spaces.

Question 16

Tuberculosis clinical comments

Answer 16

Macrophages phagocytose Mycobacterium tuberculosis, however, these bacterium cannot be digested by Macrophage.

Later damage to macrophage can release of latent TB and infection recurs.

Question 17

Lung Cancer clinical comments

Answer 17

Non-small-cell carcinoma (NSCC): most common, fast developing, typically metastatic. Most common are squamous cell carcinoma and adenocarcinoma. Affects both smokers and nonsmokers.

Small-cell carcinoma (SCC): most aggressive and rapid growing, highly malignant. Associated with smoking. Called “oat-cell” carcinoma based on cell morphology.