Lung Histology I Flashcards
What is the visceral pleura?
Serous membrane covering lung
What is the parietal pleura?
Serous membrane lining parietal wall
What is between the visceral and parietal pleura?
Intrapleural space or “cavity”- has a small amount of fluid
What three things do the pleural membranes do?
Reduce friction, acts as a lubricant
Creation of a pressure gradient, pleural pressure helps keep lungs inflated
Compartmentalization- Puts lungs in different compartments
Each lung is separate, preventing infection from moving from one lung to the other
What is air in the pleural cavity? Blood?
Pneumothorax
Hemothorax
What is the cluster of sacs at the end of the alveolar duct?
Alveolar sac
The _______ ______ is “the bunch of grapes” while the ______ is “one grape”
Alveolar sac
Alveolus
How many alveoli are in the lungs?
300 million alveoli in the lungs (150m/lung)
What epithelium lines the alveoli?
Simple squamous
What surrounds each alveolus?
Surrounded by an extensive network of capillaries for O2/CO2 exchange
Elastic fibers surround each alveolus
What is an alveolar pore? What does it do?
These connect adjacent alveoli, allow air pressure to be equalized
What are the 3 types of cells in an alveolus?
Type 1
Type II
Alveolar Macrophages
What is a type I alveolar cell?
Simple squamous lining cells, forming 95% of the surface area
Thinness allows for rapid gas diffusion to blood capillary
What is a type 2 alveolar cell? What does it produce? What are they also called?
Round to cuboidal in shape, 5% of the surface area, not flat
Produce the alveolar fluid, which contains antimicrobial proteins and surfactant
Great alveolar cells
The alveolar macrophage is also known as a…
Dust cell
What do dust cells do?
Wander around inside the lungs and “tree”
Although we breathe in huge numbers of infectious microbes in each breath, the alveolar surfaces are usually sterile
What happens to dead dust cells?
Dead dust cells get swept up by the ciliary current and are carried passively to the pharynx
What does alveolar surfactant do?
Lowers the surface tension of alveolar fluid
What substances make up alveolar surfactant?
A lipoprotein and phospholipid containing fluid
How thick is the layer of alveolar surfactant? What would happen without it?
These surfactant molecules form a mono-molecular layer over the surface of all alveoli
The attractive force of the molecules would collapse the alveoli
What is the respiratory membrane?
The barrier between alveolar air and blood
How thick is the respiratory membrane?
0.5 μm total thickness, 15 times thinner than a piece of paper
How much surface area for respiration do we have in the lungs?
Total surface area for gas exchange in adult lungs is 35x total body surface area
760 cubic feet or half a tennis court
What supplies blood to the lungs?
Pulmonary arteries: Supply deoxygenated blood
Bronchial arteries: Supply oxygenated blood
How does O2 get from inside an alveolus to the blood?
Alveolar air Surfactant Alveolar fluid Type I cell Basement membrane (type I cell) Basement membrane (endothelium) Endothelial cell Blood
What is a nasal sinus?
Air-filled spaces in bones of the skull
What are the 4 nasal sinuses?
Maxillary sinus
Frontal sinus
Ethmoidal air cells
Sphenoidal sinus
Nasal sinuses are lined with _______ ______ and drain into the _______ _______.
mucous membranes
nasal cavities
Where do the paranasal sinuses drain?
Superior and middle meatus
Where does the lacrimal duct drain?
Inferior meatus
What are two other functions of the sinuses?
These sinuses reduce the weight of the skull and serve as a resonating chamber for voice
What is sinusitis?
Acute or chronic inflammation of the sinuses.
Physiologically, what happens when we have a sinus headache?
If the membranes swell enough to block drainage into the nasal cavity, fluid pressure builds up in the paranasal sinuses, and a sinus headache results
What is the medical term for a collapsed lung?
Atelectasis
