Respiratory System Histology

Question 1

What is respiratory epithelium

Answer 1

Pseudostratified ciliated columnar epithelium with goblet cells

Question 2

What does the nasal cavity provide

Answer 2

An extensive area for 
1. Warming
2. Moistening
3. Filtering 
the inspired air 

Roof contains an area of specialised olfactory epithelium

Question 3

How does the lining of the nasal cavity change

Answer 3

The initial part, vestibule is lined by keratinised stratified squamous epithelium
Deeper, the keratin is lost and deeper still it changes to respiratory epithelium

Question 4

Histology of the oropharynx and epiglottis

Answer 4

As oropharynx transmits air and swallowed food, needs to resist abrasion so lined with non-keratinised stratified squamous epithelium.
Same as the anterior surface and upper part of the posterior surface of the epiglottis

Question 5

Histology of the larynx

Answer 5

Walls made up of cartilage and muscles with respiratory epithelium lining its surfaces.

Exception is vocal cords and adjacent structures which are covered with stratified squamous epithelium

Question 6

Histology of the trachea

Answer 6

Contains 15-20 C shaped cartilages. Open side spanned by fibroelastic tissue and smooth muscles (trachealis muscle)

Wall of trachea includes a lining of respiratory epithelium backed by a basal lamina, a lamina propria of connective tissue with abundant elastic fibres and a submucosa of connective tissue that includes numerous seromucous glands

Question 7

Histology of the bronchi

Answer 7

Trachea divides into two main bronchi and rings of hyaline cartilage are replaced by irregularly shaped cartilage plates.
Wall of bronchus is made up of RE, LP, a muscularis consisting of a ring of smooth muscle and a submucosa with adipose tissue and some seromuscous glands

Question 8

What happens to the cartilage as you go down the bronchial tree

Answer 8

Cartilage becomes more discontinuous and is lost when airway is about 1mm in diameter - bronchioles

Question 9

Histology of bronchioles

Answer 9

Less than 1mm in diameter and lack cartilage and glands but may contain a few goblet cells in their initial portion

Epithelium decreases in height from columnar to cuboidal as you progress down tree

Lamina propria is composed of smooth muscle and elastic and collagenous fibres

Question 10

Smooth muscle function in bronchioles

Answer 10

Respond to parasympathetic innervation, histamine and other factors by contracting and constricting diameter of bronchiole.
Plays a role in asthma attacks and allergic reactions

Question 11

Histology of terminal bronchioles

Answer 11

Lined with cuboidal ciliated epithelium and contain non-ciliated club cells

Question 12

Roles of club cells

Answer 12

Stem cells
Detoxification
Immune modification
Surfactant production

Question 13

What are the alveoli

Answer 13

Alveoli are the terminal process if bronchial tree and responsible for spongy nature of lungs. Resemble thin walled pockets like honeycomb.
O2 and CO2 are exchanged
300 million alveoli in each lung

Question 14

Type 1 alveolar cells

Answer 14

Simple squamous epithelium that lines alveolar surfaces covering over 90% of alveolar surface

Provide barrier of minimal thickness that is permeable to gases

Question 15

Type 2 alveolar cells

Answer 15

Polygonal in shape