Respiratory Histology

Question 1

Conduction portion of the RT

Answer 1

Collects and warms air.
Transmits air to respiratory portion.
Includes: nasal cavity, paranasal sinuses, nasopharynx, trachea, brochi and terminal bronchi.

Question 2

Respiratory portion of the RT

Answer 2

Passes air to alveoli to assist in gas exchange.

Includes: respiratory bronchioles, alveolar ducts, alveolar sacs.

Question 3

Respiratory epithelium

Answer 3

Pseudostratified columnar ciliated epithelium.
Includes a lamina propria which has a rich, vascular network w/ set of capillary loops.
Exist only in the airways.

Question 4

Goblet cells

Answer 4

Secrete mucus via exocytosis.

Exist within the epithelium to trap foreign invaders.

Question 5

Nasal cavities divided by nasal septum into 3 regions:

Answer 5

Nasal vestibule: inside of nostrils (lined by skin).
Respiratory region: inferior 2/3 of nasal cavities, lined with respiratory mucosa.
Olfactory region: upper 1/3 of cavity. Lined with olfactory mucosa.

Question 6

Function of the nasal cavity

Answer 6

Adjust tempirature and humidity of inspired air. Enhanced by large surface area from turbinate bones.

Question 7

Epithelium of nasal vestibule

Answer 7

Keratinized stratified squamous epithelium.

Question 8

Epithelium of respiratory region of the nasal cavity

Answer 8

Pseudostratified columnar ciliated epithelium.

Question 9

Olfactory mucosa

Answer 9

Has receptors for sense of smell.
Pseudostratified ciliated columnar epithelium.
Olfactory glands have serous secretions that dissolve odorant molecules.
**Hallmark: much thinner, lacks goblet cells.

Question 10

Olfactory receptor cells

Answer 10

Have single dendritic process.

Have nonmotile cilia w/ odorant receptors that transmit signal to olfactory bulb.

Question 11

Basal cells of olfactory mucosa

Answer 11

Stem cells for olfactory receptor and supporting cells.

Question 12

Brush cells of olfactory mucosa

Answer 12

Ciliated, columnar epithelial cells.

Question 13

Supporting/sustentacular cells of olfactory mucosa

Answer 13

Mechanical and metabolic support to olfactory receptor cells.

Question 14

Trachea overview

Answer 14

Short and flexible conduit for air.
Extends from larynx and divides into main bronchi.
Lumen remains open due to cartilaginous rings.

Question 15

Trachea has 4 layers which are:

Answer 15

Mucosa: ciliated pseudostratified epithelium and an elastic rich LP.
Submucosa: slightly denser CT than LP.
Cartilaginous layer: C-shaped hyaline cartilage.
Adevntitia: CT that binds trachea to adjacent structures.

Question 16

Epithelium of terminal bronchioles

Answer 16

Simple cuboidal epithelium w/ clara cells.

Question 17

Clara cells

Answer 17

Secrete lipoprotein substance that prevents luminal adhesion w/ airway collapse during exhalation.

Question 18

Respiratory bronchioles

Answer 18

Simple cuboidal epithelium.
Elastic fibers.
Smooth muscle.

Question 19

Branching of respiratory bronchiole

Answer 19

RB –> alveolar duct –> alveolar sac.

Question 20

Alveoli overview

Answer 20

Lined with type I and type II pneumocytes.

Simple squamous epithelium.

Question 21

Alveolar septum

Answer 21

Wall of alveolar capillaries surrounded by elastin and collagen fibers.

Question 22

Alveolar pores

Answer 22

Small openings that permit movement of air between alveoli.

Question 23

Type I pneumocytes

Answer 23

Line almost entirety of alveolar surface.
Creates surface for gas exchange.
In close association with capillaries.

Question 24

Type II pneumocytes

Answer 24

Rounded cells comprising about 60% of epithelium, but cover 5% of surface area.
More numerous.
Secrete surfactant to prevent collapse.

Question 25

Asthma

Answer 25

Chronic inflammation of airways.
Restriction of airflow due to inflammation and bronchospasm.
Infiltration of eosinophils, lymphocytes and MCs.
Thick bronchiolar epithelium w/ increased goblet cells, thick BM and hyperplastic smooth muscle cells.

Question 26

Emphysema

Answer 26

Enlargement of airspaces distal to terminal bronchiole.
Destruction of alveolar walls.
Poor gas exchange.

Question 27

Pneumonia

Answer 27

Inflammation of lung tissue.
Air spaces filled with WBCs, RBCs and fibrin.
Enlarged capillaries congested with RBCs.
Lung appears red due to increase in RBCs.

Question 28

Visceral pleura

Answer 28

Covered in a flattened, mesothelium.
Underlying fibrous tissues of collagen and elastin fibers.
Extends into the lung as fibrous septa.
Has extensive lymphatic vessels.