Respiratory Histology

Question 1

What structures make up the upper respiratory tract?

Answer 1

• Nasal cavity
• Paranasal sinuses
• Pharynx
• Larynx (proximal half)

Question 2

What is the main function of the upper respiratory tract`?

Answer 2

To warm, humidify and filter air

Question 3

What bone is in the nasal cavity?

Answer 3

Has shelves of bone called conchae, or turbinates

Question 4

What is the function of conchae?

Answer 4

Increase the surface area of the nasal cavity, for rapid warming and humidification of air

Question 5

What are paranasal sinuses?

Answer 5

Spaces in bones. Produce mucus that drains into the lateral walls of the nasal cavity

Question 6

What is the function of the larynx?

Answer 6

• When open allows airways into the trachea
• Contains vocal cords that come together close the airways with movement from the epiglottis
• Vibration of these vocal cords produces sound

Question 7

What is the epiglottis and what is its function?

Answer 7

A flap of tissue that sits beneath the tongue at the back of the throat. Closes over the windpipe while you eat to prevent food entering the airway

Question 8

What does the conducting airway consist of?

Answer 8

Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles

Question 9

What is the function of the conducting airway?

Answer 9

To warm, humidify, and filter air

Question 10

What type of respiratory epithelium does the conducting airway consist of?

Answer 10

Pseudostratified columnar ciliated epithelium with numerous goblet cells

Question 11

What does the pseudostratified columnar epithelium contain?

Answer 11

• Has ciliated cells
• Goblet cells
• Basal cells (divide to form new cells)
• Basement membrane
• Not visible K cells- neuroendocrine cells
• Underlying lamina propria

Question 12

What is mucociliary clearance?

Answer 12

Where the cilia beat in a unidirectional fashion to clear the mucus towards the pharynx, containing possible pathogens
-the mucus can then be coughed up or swallowed

Question 13

What are the different layers of respiratory tract tissue?

Answer 13

• Respiratory mucosa
• Submucosa
• Muscularis/Cariligenous layer
• Adventitia

Question 14

What does the respiratory mucosa consist of?

Answer 14

• Epithelium, underlying basment membrane and lmaina propria

- Goblet cells that gradually decrease distally

Question 15

What does the respiratory submucosa consist of?

Answer 15

• Connective tissue containing seromucous glands

- Serous and mucous glands that gradually decrease distally

Question 16

What does the respiratory muscularis/cartilaginous layer consist of?

Answer 16

• Cartlidge that disappears distally

- Smooth muscle- the amount depends on the region

Question 17

Describe the bonchial tree

Answer 17

Trachea, bronchi, bronchioles, terminal bronchioles, respiratory broncioles, alveolar ducts, alveolar sacs, alveoli

Question 18

Describe the histology of the trachea?

Answer 18

• Respiratory mucosa
• Submucosa
• Cartilaginous layer- consisting of 15-20 C-shaped cartlidges and cartlidge bridged posteriorly by smooth muscle and fibroelastin fibres (trachealis)
• Adventitia

Question 19

What is the trachealis?

Answer 19

The trachelais muscle is a smooth muscle that bridges the free ends of the C shaped cartlidges at the posterior border of the trachea
-function is the constrict the trachea, allowing air to be expelled with more force e.g in coughing

Question 20

How does the type of epithelium change from the terminal bronchioles to the respiratory bronchioles?

Answer 20

Terminal bronchioles are columar ciliated epithelia with very few goblet cells
Respiratory bronchioles are cuboidal epithelia with no goblet cells but contain clara cells

Question 21

How does the epithelia change from the trachea to the terminal bronchioles ?

Answer 21

With each division:
Less cartlidge 
Less goblet cells
More smooth muscle
Introduction of clara cells distally on terminal bronchioles

Question 22

What are clara cells?

Answer 22

Secretes surfactant - a substance which reduces the surface tension of a surface

Question 23

What does the lower respiratory system consist of?

Answer 23

Trachea
Bronchi
Bronchioles and alveoli (lungs)

Question 24

What does the respiratory airway consist of?

Answer 24

Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli

Question 25

Describe the histology of the alveolar region (Alveolar ducts, sacs and alveoli)

Answer 25

Squamous epithelia (flat for optimum gas exchange) with no cilia
Cells are called pneumocytes
Type 1 pneumocytes- flat and share basal lamina with endothelial cells for gas exchange
Type 2 pneumocytes- round cells that secrete surfactant

Question 26

What is the difference between type 1 and type 2 pneumocytes?

Answer 26

Type 1- thin squamous epithelia forming the extrememly thin gaseous diffusion barrier, nuclei flattened
Type 2- rounded, produce surfactant- which prevents collapse of alveoli by reducing surface tension

Question 27

What type of immune cells is present in the respiratory tract and why is it there?

Answer 27

Macrophages are present

-aid in phagocytosis and removal of foriegn debris