histology of the respiratory tract

Question 1

what does the upper respiratory tract consist of?

Answer 1

• nose
• pharynx
• paranasal sinuses
• larynx

Question 2

what does the lower respiratory tract consist of?

Answer 2

• trachea
• primary, secondary, tertiary bronchi
• bronchioles — conducting, terminal and respiratory
• alveoli — ducts, sacs and alveoli

Question 3

what are the 4 layers of the trachea?

Answer 3

1. mucosa
2. submucosa
3. cartilaginous layer
4. adventitia

Question 4

describe the musosa layer of the trachea

Answer 4

• epithelium = pseudostratified columnar ciliated epithelium with goblet cells
• lamina propria (loose connective tissue) = contains elastin — continuous with submucosa

Question 5

describe the submucosa layer of the trachea

Answer 5

loose connective tissue

Question 6

describe the cartilaginous layer of the trachea

Answer 6

• c-shaped hyaline cartilage rings

- trachealis muscle

Question 7

describe the adventitia layer of the respiratory tract

Answer 7

• connective tissue layer that merges with connective tissue of other organs

Question 8

name the pink cells and their function

name the pink cells and their function

Answer 8

goblet cells — produce mucus

Question 9

what is the epithelium of the trachea?

Answer 9

pseudostratified ciliated columnar epithelium with goblet cells

Question 10

as the respiratory tubes get smaller, name 3 things that happen

Answer 10

1. amount of cartilage decreases
2. amount of smooth muscle increases
3. height of epithelial cells decreases

Question 11

what do the epithelial cells in the bronchi turn from and to?

Answer 11

stratified —> simple cuboidal (gradual transition)

Question 12

describe the primary bronchi

Answer 12

• supply each lung
• 2-3cm long
• c-shaped cartilages
• right is wider and more vertical than the left

Question 13

describe the secondary bronchi

Answer 13

• supply lobes of lungs
• 3 RHS, 2 LHS
• plates of cartilage

Question 14

describe the tertiary bronchi

Answer 14

• supply segments of the lung
• 10 RHS, 8 LHS
• plates of cartilage

Question 15

as you go down the resp tract, how does the epithelium change?

Answer 15

pseudostratified columnar epithelium —> simple columnar epithelium

Question 16

where is this from and how do you know?

Answer 16

surrounded by lung tissue — intrapulmonary therefore secondary or tertiary bronchus

Question 17

identify 1, 2, 3, 4

Answer 17

1. submucosa
2. smooth muscle
3. lamina propria
4. ciliated epithelium

Question 18

what is circled?

Answer 18

a plate of cartilage

Question 19

what are bronchioles capable of?

Answer 19

bronchoconstriction and bronchodilation

Question 20

what are bronchiole walls supported by?

Answer 20

smooth muscle

Question 21

is there cartilage present in bronchioles?

Answer 21

no

Question 22

describe conducting bronchioles

Answer 22

• simple ciliated columnar epithelium
• goblet cells
• each give rise to 50-80 terminal branches

Question 23

describe terminal bronchioles

Answer 23

• simple ciliated columnar/cuboidal epithelium
• no goblet cells or mucous glands
• clara cells
• each give rise to 2 more respiratory brochioles

Question 24

what do clara cells do?

Answer 24

produce surfactant

Question 25

describe respiratory bronchioles

Answer 25

- simple cuboidal — no cilia - clara cells - alveoli extend from the lumen — gas exchange occurs here

Question 26

what are alveolar ducts?

Answer 26

- respiratory bronchioles give rise to alveolar ducts | - elongated airways with walls made of alveolar sacs

Question 27

what are alveolar sacs?

Answer 27

spaces surrounded by clusters of alveoli

Question 28

identify 1, 2, 3, 4, 5

Answer 28

1. terminal bronchiole 2. respiratory bronchiole 3. alveolar duct 4. alveolar sac 5. alveolus

Question 29

what epithelium is present on type 1 alveolar cells?

Answer 29

simple squamous

Question 30

describe the respiratory membrane

Answer 30

- epithelium of type 1 cell - basement membrane of type 1 cell - basement membrane of capillary - endothelium of capillary (2 basements tend to be fused together)

Question 31

how can the diffusion distance be increased across the respiratory membrane? give an example of when this happens

Answer 31

fluid can collect between 2 basement membranes and push them apart — makes it harder for gases to get across eg. in pulmonary hypertension (increases diffusion distance)