9.2 - Lab + Lecture Notes Flashcards
Describe a distinguishing aspect of the lamina propria in the trachea
- rich in elastic fibers
- no glands in this layer
Describe the tracheal Hyaline Cartilage and its distinguishing aspects
- stacked C-shaped rings
- openings point away from ventral surface
- location of tracheal is muscle
What is BALT?
= bronchial associated lymphoid tissue (a type of MALT)
- congregations where motile CT cells are likely to encounter foreign antigens
What are the intrapulmonary bronchi?
= largest of respiratory airways –> surrounded by lung tissue
- easiest to recognize because they retain cartilage in wall
- end of branching of these bronchi into smaller structures are the bronchioles
Describe the bronchioles
- exhibit a change in epithelium from pseudo stratified to domed cuboidal/low columnar cells –> called Clara Cells
- the epithelium of Clara cells still functions as a conducting epithelium
What are Clara cells and where are they found?
- Clara cells are found starting in the bronchioles and represent a shift in the epithelium from pseudo stratified in high airways to their characteristic domed cuboidal shape
- secrete a serous fluid that better traps fine particles that penetrate deep into the lung
Where in the respiratory system will you find a pseudostratified epithelium known as the “respiratory epithelium”
- refers the the conducting airway portions of the lung (nose, trachea, bronchi)
- does not refer to respiratory portions (they have an alveolar epithelium)
List the airways that pass from the bronchiolar to the alveolar epithelium
1) Terminal bronchi
2) Respiratory Bronchi
3) Alveolar Duct
4) Alveolar Sac
Describe the terminal Bronchiole
- last airway completely lined witha conduction (Clara cell) epithelium
- connects the bronchi/bronchioles to the respiratory bronchiole
Describe the Respiratory bronchiole
- passageway lined mostly with a Clara cell epithelium,
- but containing patches of alveolar epithelium
- Connects terminal bronchiole to the alveolar duct
Describe the Alveolar Duct
- passageway lined completely with alveolar epithelium
- Connect respiratory bronchiole to the alveolar sac
Describe the alveolar sac
- terminal passageway of the lung
- lined by alveolar epithelium
- connected to rest of airways by alveolar duct (and by alveolar pores?)
Describe the Alveolar Morphology (Dust Cell)
- normally recognized by inclusions
- not permanently attached to the epithelium
- crawl using pseudopodia
- when end useful life accumulate in corners of CT near significant collagenous tissue
- are good example of supra vital staining
What are the 4 resident cells of the alveolar epithelium
Endothelial Cells
Type I pneumocytes
Type II pneumocytes
Alveolar Macrophages
What are two classification of emphysema
1) Centriolobular
2) Panacinar
Describe Centrilobular emphysema
- affects the centers of the lung’s lobules
- -> near the respiratory airways
Describe panacinar emphysema
- affects all levels of airways
Describe the morphology of a deflated + fixated lung
- would see minimal or no air spaces between alveolar septa
Fibrosis
= accumulation of fibrous tissue
When does embryonic stage of development end, and on what day does is the lung bud formed?
- Embryonic stage ends on day 56
- on Day 22 the ventral foregut forms the respiratory diverticulum (the lung bud) - which begins growing inside the splanchnic mesoderm
Where is the epithelium of the lung derived from and what does it give rise to?
- Endoderm derived epithelium of lung
- Gives rise to
Larynx, Trachea, Bronchi, Bronchioles (proximally), parenchymal cells (distally)
What does the splanchnic mesoderm form WRT lung development
- Condensation of splanchnic mesoderm gives rise to cartilage, muscle, CT, vascular network around the lung
Describe what occurs when the respiratory diverticulum separates from the foregut
- the lung bud forms the trachea + 2 main bronchial buds
- mesoderm covering outside of lung develops into visceral pleura
- mesoderm covering body wall develops into parietal pleura
- pleural cavity develops in space between the pleura
- the bronchi then continue developing and divide repeatedly forming secondary and tertiary bronchi
Describe the difference between right and left main stem bronchi that can be seen from early on in development
- Right main stem bronchi is a little more vertical and has a larger diameter than the left
Give a brief overview of the sequences of development after embryonic period and indicate whether gas exchange is possible at the end of embryonic development
- By end of embryonic period no gas exchange sites have developed yet
- Respiratory tree continues branching to form terminal bronchioles, which then give rise to respiratory bronchioles
- respiratory bronchioles give rise to terminal sacs (also known as primitive alveoli)
- mesodermal CT becomes highly vascularized and lymphatic capillaries develop close to the primitive alveoli
What are the 4 stages of lung development following the embryonic period and what is the time frame for each?
1) Pseudoglandular period (6-16wks)
2) Canalicular Stage (16-26wks)
3) Terminal Saccular Period (26wks-birth)
4) Alveolar Period (32 wks - 8 years)
Describe the Pseudoglandular Period of Lung development, mention the possibility of fetal birth during this stage.
- timeframe: 6-16 weeks
- no gas exchange sites have formed
- thus, respiration is not possible
- fetal birth is not compatible with life
Describe the Canalicular Stage of Lung development, mention the possibility of fetal birth during this stage.
- timeframe: 16-26 weeks
- primordial alveoli have formed
- respiration is possible near the end of this period 24-26 weeks
- fetal birth would allow life, but serious complications requiring extensive long care would result
Describe the Terminal Saccular Period of Lung development, mention the possibility of fetal birth during this stage.
- timeframe: 26 week - birth
- CT is thinning and surfactant production begins increasing very the very small amount that is being produced beginning at weeks 22-24
- depending on immaturity of lungs and how early the baby is born the lack of production of surfactant can cause respiratory distress such as NRDS (Hyaline membrane disease)
Describe the Alveolar Period of Lung development
- Timeframe: 32 weeks - 8 years
- at 8 years lung development is considered complete