histology of the respiratory tract Flashcards
what does the upper respiratory tract consist of?
- nose
- pharynx
- paranasal sinuses
- larynx
what does the lower respiratory tract consist of?
- trachea
- primary, secondary, tertiary bronchi
- bronchioles — conducting, terminal and respiratory
- alveoli — ducts, sacs and alveoli
what are the 4 layers of the trachea?
- mucosa
- submucosa
- cartilaginous layer
- adventitia
describe the musosa layer of the trachea
- epithelium = pseudostratified columnar ciliated epithelium with goblet cells
- lamina propria (loose connective tissue) = contains elastin — continuous with submucosa
describe the submucosa layer of the trachea
loose connective tissue
describe the cartilaginous layer of the trachea
- c-shaped hyaline cartilage rings
- trachealis muscle
describe the adventitia layer of the respiratory tract
- connective tissue layer that merges with connective tissue of other organs
name the pink cells and their function
goblet cells — produce mucus
what is the epithelium of the trachea?
pseudostratified ciliated columnar epithelium with goblet cells
as the respiratory tubes get smaller, name 3 things that happen
- amount of cartilage decreases
- amount of smooth muscle increases
- height of epithelial cells decreases
what do the epithelial cells in the bronchi turn from and to?
stratified —> simple cuboidal (gradual transition)
describe the primary bronchi
- supply each lung
- 2-3cm long
- c-shaped cartilages
- right is wider and more vertical than the left
describe the secondary bronchi
- supply lobes of lungs
- 3 RHS, 2 LHS
- plates of cartilage
describe the tertiary bronchi
- supply segments of the lung
- 10 RHS, 8 LHS
- plates of cartilage
as you go down the resp tract, how does the epithelium change?
pseudostratified columnar epithelium —> simple columnar epithelium
where is this from and how do you know?
surrounded by lung tissue — intrapulmonary therefore secondary or tertiary bronchus
identify 1, 2, 3, 4
- submucosa
- smooth muscle
- lamina propria
- ciliated epithelium
what is circled?
a plate of cartilage
what are bronchioles capable of?
bronchoconstriction and bronchodilation
what are bronchiole walls supported by?
smooth muscle
is there cartilage present in bronchioles?
no
describe conducting bronchioles
- simple ciliated columnar epithelium
- goblet cells
- each give rise to 50-80 terminal branches
describe terminal bronchioles
- simple ciliated columnar/cuboidal epithelium
- no goblet cells or mucous glands
- clara cells
- each give rise to 2 more respiratory brochioles
what do clara cells do?
produce surfactant
describe respiratory bronchioles
- simple cuboidal — no cilia
- clara cells
- alveoli extend from the lumen — gas exchange occurs here
what are alveolar ducts?
- respiratory bronchioles give rise to alveolar ducts
- elongated airways with walls made of alveolar sacs
what are alveolar sacs?
spaces surrounded by clusters of alveoli
identify 1, 2, 3, 4, 5
- terminal bronchiole
- respiratory bronchiole
- alveolar duct
- alveolar sac
- alveolus
what epithelium is present on type 1 alveolar cells?
simple squamous
describe the respiratory membrane
- 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)
how can the diffusion distance be increased across the respiratory membrane? give an example of when this happens
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)
