Respiratory Histology

Question 1

What is the conduction portion?

Answer 1

Carry air, and involved in air conditioning,, filtration, defence, sense of smell and sound production

Question 2

What is the respiratory portion?

Answer 2

Where gas exchange takes place

Question 3

What is the upper respiratory tract?

Answer 3

Nasal cavity, paranasal sinuses, nasopharynx and ends at larynx

Question 4

What is the lower respiratory tract?

Answer 4

Trachea, bronchi, to terminal bronchioles

Question 5

Describe the divisions of the conducting portion of the respiratory system

Answer 5

Trachea –> L and R main bronchi –> lobar bronchi –> segmental bronchi –> bronchioles –> terminal bronchioles

Question 6

Describe the divisions of the respiratory portion of the respiratory system

Answer 6

Respiratory bronchioles –> alveolar ducts –> alveolar sacs –> alveoli

Question 7

Describe the epithelia of the upper respiratory tract

Answer 7

Ciliated pseudostratified columnar epithelia with goblet cells

Question 8

How does epithelia change with bronchial divisions?

Answer 8

As shrink in diameter –> gradual decrease in goblet cell number and transition to ciliated simple columnar and then to simple cuboidal epithelia

Question 9

Describe the epithelia of the pharynx

Answer 9

Has stratified squamous epithelium (to resist abrasion)

Question 10

Which cells contribute to the formation of mucus?

Answer 10

Submucosal mucous glands and goblet cells

Question 11

What is the composition of the secretions in the respiratory tract?

Answer 11

Mucus contains mucin, water, ions, IgA and lysozyme

Question 12

Describe the histology of the trachea

Answer 12

Epithelia: Ciliated pseudostratified
Lamina propria: lots of elastin and lymphoid tissue
Submucosa: mucous glands
Cartilage: C-shaped rings of hyaline cartilage outside submucosa

Question 13

Describe the histology of the bronchi

Answer 13

Epithelia: ciliated pseudostratified (less goblet cells)
Lamina propria: greater elastic tissue
Muscularis mucosa: begins to form
Cartilage: in plates not rings

Question 14

How does cartilage differ down the respiratory tract?

Answer 14

Starts off as C-shaped rings, then plates, then no cartilage at all

Question 15

How does epithelia in primary bronchi differ to tertiary bronchi?

Answer 15

Primary bronchi = ciliated pseudostratified

Tertiary bronchi = simple columnar epithelia with few cartilage plates and mucous glands (in submucosa)

Question 16

What are clara cells?

Answer 16

Secretory cells with unclear function

Question 17

How do bronchioles differ from other structures in the conducting airway?

Answer 17

Has no cartilage or mucous glands

Question 18

How are bronchioles kept open?

Answer 18

Radial traction of elastic fibres

Question 19

Describe the histology of the bronchioles

Answer 19

Epithelia: ciliated columnar epithelium with few goblet cells (and few clara cells)
Muscularis mucosae: prominent to control air flow

Question 20

Describe the histology of respiratory bronchioles

Answer 20

Epithelia: cuboidal ciliated epithelia and clara cells

Smooth muscle in walls (muscularis mucosae)

Question 21

What is a pulmonary/respiratory acinus?

Answer 21

Functional unit of lung; all components involved in respiratory exchange

Question 22

What cells do alveoli contain?

Answer 22

Type I and II pneumocytes and pulmonary macrophages

Question 23

What are type I pneumocytes?

Answer 23

Simple squamous cells covering most of alveolar wall

Question 24

What are type II pneumocytes?

Answer 24

Cuboidal cells which produce surfactant

Question 25

What is the role of pulmonary macrophages?

Answer 25

Breakdown particulate matter and microorganisms

Question 26

What is the blood-air barrier formed by?

Answer 26

Type I pneumocytes, basement membrane and pulmonary capillary endothelium

Question 27

What is meant by ‘interalveolar septa’?

Answer 27

Where adjacent alveoli form septum consisting of epithelia lining of alveoli on each side with thin loose CT inbetween

Question 28

How do lobar bronchi differ between the left and right lungs?

Answer 28

Right lung has 3 lobes, left lung only has 2

Question 29

What molecules affect the muscularis mucosae of the bronchioles?

Answer 29

Autonomic nervous system neurotransmitters, adrenal medullary hormones and local factors