Flashcards in Respiratory System Deck (80)
How do neighboring alveoli connect to one another and why?
connect with each other via pores, providing equalization of pressure and collateral ventilation if a bronchiole is obstructed.
What do the pores allow the passage of? (between alveoli)
What cells are found in the alveolar septum and interstium?
- fibroblasts, capillaries
- DUST cells (actually macrophages)
- collagen type III is present in alveolar wall
- collagen type I present in conducting airways
- elastic fibers
Where are pneumocytes Type I found and what are their characteristics?
- form walls of alveoli and are extremely thin with occluding junctions which prevent fluid passage
- organelles are grouped around the nucleus
- are not mitotic - so no regeneration
- compose 95% of the alveolar sufaces
What is the function of a type I pneumocyte cell?
What type of capillaries are found in the alveoli?
What are type II pneumocytes and what are their characteristics?
- account for 5% of alveolar surface area
- secretory cells (more granular in appearance)
- surfactant is produced via lamellar bodies
- can be mitotic --> produces both type I and II pneumocytes (if damage is not continuous and severe)
What do the lamellar granules of type II pneumocytes contain?
What is surfactant?
mono-molecular layer of phospholipoprotein that functions to reduce surface tension, reducing the effort needed to inflate the alveoli, thus preventing alveolar collapse (known as atelectasis)
- constantly produced by type II pneumocytes
What stimulates the production of surfactant in the fetus just prior to parturition?
What is atelectasis?
What is hyaline membrane disease?
absence of surfactant in newborns
What is the blood-air barrier composed of?
- 2 fused basal laminae of alveolar epithelium and endothelium of capillary
- cytoplasm of type I pneumocyte covered by surfactant
What are PAMs and PIMs?
PAMs = alveolar macrophages (dust cells)
PIMS = intravascular macrophages
Where are macrophages found?
in tissues and organs: loose CT, liver, Lungs, Spleen and lymph nodes, serous cavities, nervous tissue and bone
True or false? There are lymphatic vessels in the alveolar walls.
Where do the lymphatic vessels of the respiratory system drain towards?
What are the lungs lined by and covered by and what is it composed of?
- Lined by simple squamous epithelium
- covered by the visceral pleura which is composed of connective tissue
What does the connective tissue surrounding the lung do?
supports the bronchial tree and separates the lung into lobes