Histology - Resp.

Question 1

What is the physical process of respiration?

Answer 1

Ventilation which involves inspiratory and expiratory movement of the chest wall

Question 2

What is the chemical process of respiration?

Answer 2

Exchange of gases between air and blood takes place at cellular level

Question 3

What is the autonomic innervation of the respiratory system?

Answer 3

Parasympathetic - bronchoconstriction, mucous secretion and vasodilation
Sympathetic - bronchodilation

Question 4

What are the 4 main layers of the respiratory system?

Answer 4

Mucosa
Submucosa
Cartilage and/or muscle layer
Adventitia

Question 5

Describe the histology of the trachea

Answer 5

Wide flexible tube with 20 C-shapes tracheal cartilages
Gaps between rings are filled by trachealis muscle and fibroelastic tissue
Mucosa and submucosa are adapted to warm and moisten the air

Question 6

What is the nature of the C-shaped cartilage rings of the trachea?

Answer 6

Hyaline

Question 7

Explain the mucosa of the trachea

Answer 7

Epithelium - ciliated pseudostratified columnar epithelium with goblet cells
Lamina propria - is underneath the epithelium and contains elastin and blood vessels

Question 8

Explain the submucosa of the trachea

Answer 8

Mixed sero-mucous glands - watery secretion from serous glands humidify the air
Mucus from goblet cells traps particles from the air - keeps free from bacteria

Question 9

Explain the adventitia of the trachea

Answer 9

Connects and supports trachea to surrounding tissue - thyroid and oesophagus
Contains nerves, vessels and adipose tissue

Question 10

Describe the histology of the extrapulmonary bronchi

Answer 10

Closely resemble the trachea histologically

Question 11

Describe the histology of the intrapulmonary bronchi

Answer 11

There is less cartilage then trachea and it does not completely circle the lumen
Contains layers of smooth muscle between the mucosa and submucosa

Question 12

Describe the histology of bronchioles

Answer 12

Pseudostratified ciliated columnar epithelium decreases in height in the bronchioles to become simple columnar to cuboidal epithelium
Smooth muscle increases and Clara cells are present
No goblet cells, non-ciliated cells, no submucosal glands and no cartilage

Question 13

What do Clara cells do?

Answer 13

Secretes surfactant

Question 14

Describe the histology of the terminal and respiratory bronchioles?

Answer 14

Terminal bronchiole is lined by simple cuboidal epithelium with Clara cells and give rise to respiratory bronchiole
Respiratory bronchiole is lines with low cuboidal epithelium

Question 15

Describe the histology of alveolar ducts?

Answer 15

Surrounded by smooth muscle, elastin and collagen

Question 16

What are the major characteristics of bronchioles?

Answer 16

Lack cartilage and smooth muscle layer is relatively thicker
Many non-ciliated Clara cells in epithelium
No glands in the lamina propria

Question 17

What are type I pneumocytes?

Answer 17

Large flattened cells which present a very thin diffusion barrier for gases

Question 18

What are type II pneumocytes?

Answer 18

These cells secrete surfactant which decreases alveolar surface tension and stops alveolar collapse

Question 19

What are dust cells - macrophages in the alveoli?

Answer 19

Found in the lumen of the alveolus
Have brownish appearance

Question 20

Describe the alveolar-Capillary/ Blood-Air interface

Answer 20

Gaseous exchange takes place through the endothelial cell of the capillary, basement membrane and type I pneumocyte
Wall of capillary endothelial cell is fused to alveolar cell, and only thin basement membrane between

Question 21

What is the conducting portion characterised by?

Answer 21

Pseudostratified columnar epithelium with cilia
Goblet cells
Gland tissue
Hyaline cartilage

Question 22

What is the respiratory portion (begins at respiratory bronchioles) characterised by?

Answer 22

Epithelium gradual transition from cuboidal to simple squamous
Cartilage ends
Abundant smooth muscle, elastic fibres and reticular fibres