Unit 6 - Respiratory System Flashcards
What are the two membranes of the pleura?
- Parietal pleura
2. Visceral pleura (against the lungs)
What is the space called between the parietal and visceral pleura?
Pleural space
- contains a little fluid
What is each lung surrounded by?
Pleural cavity
What are the functions of the pleurae and pleural fluid (3)?
- Reduction of friction
- Creation of pressure gradient
- Compartmentalization
Regarding the atmospheric, pleural and alveolar pressures, which is greatest? which is lowest?
P(atm) > P(alv) > P(pl)
Why is it important that atmospheric pressure is greater than alveolar pressure?
So we can breathe in!
- pressure goes from HIGH to LOW
Why doesn’t the atmospheric pressure collapse the lungs?
Because of pleural pressure
- pleural pressure is lower than alveolar pressure and keeps the alveoli INFLATED
Why might breathing become impossible if there is inflammation of the pleura?
This would increase the pressure of the pleura, collapsing the alveoli
What is the benefit of compartmentalization of the lungs?
Helps to prevent/reduce the spread of infection
What does the upper respiratory tract consist of (3)?
- Nasopharynx
- Oropharynx
- Larynx
(Sometimes trachea is included too)
What does the lower respiratory tract consist of (4)?
- Trachea
- L and R primary bronchi
- Bronchioles
- Lungs
What is extrathoracic? (Where is it?)
Trachea and UP!
What is intrathoracic?
Where is it?
Bronchi and DOWN!
What are the 3 functions of the upper respiratory tract?
- Filters incoming air
- Humidifies incoming air
- Warms incoming air
Why is it important that air is humidified on the way INTO the lungs?
So that when you exhale air from the lungs, you don’t lose any more moisture
What does the tracheobronchial tress consist of?
- Trachea
- Bronchi
- Terminal bronchioles
- 23-28 branches of conducting tubes
How are conducting tubes different than alveoli?
Conducting tubes cannot exchange air between the blood and the airway
Where along the respiratory tract is smooth muscle present?
Wall of the bronchi and bronchioles
- amount of smooth muscles increases distally to the small bronchi then decreases and is eventually absent at the respiratory bronchioles
Where along the respiratory tract is cartilage present?
In the wall of the trachea and bronchi
- amount of cartilage decreases distally and disappears in the terminal bronchioles
What does smooth muscle in the wall of the bronchi and bronchioles help to control?
Airway conductance
What is the functional role of the smooth muscle around the airways?
Prevent inhalation of toxic, pollen, dust, etc.
- If there is an irritant in the air (smoke, dust, glass particles), if the airways don’t constrict, the person will suffer a lot of damage to the airways
What is the role of tracheobronchial epithelium?
Mucus-secreting ciliated epithelium
- Traps particles
- Cilia beat to expel trapped particles
What happens to tracheobronchial epithelium if you are a chronic smoker?
Metaplasia: epithelium
- stratified squamous epithelium (cannot produce mucus)
- higher risk of respiratory infections
- ability to filter is reduced
Where does gas exchange take place?
- Respiratory bronchioles
- Alveoli
What is the function of elastic and collagen fibers in alveoli?
Collagen = restricts stretch (can't over-inflate) Alveoli = ability to recoil
What happens to the connective tissue of alveoli in COPD (emphysema)?
Fibers are getting destroyed
- ability to prevent over-inflation is lost as well as ability to recoil
- alveoli get BIG!
Describe the relationship between alveoli and blood vessels.
When an alveoli is open, there is blood flow.
When an alveoli is closed, the blood vessels collapse (poor blood flow through lungs)
What facilitates gas exchange between the alveolar lumen and the blood?
Thin membrane
- intimate contact with a rich network of capillaries
What do Type 1 alveolar cells do? What do they look like?
Simple squamous epithelium (FLAT CELLS)
- facilitates diffusion of gases between bloodstream and alveoli)
What do Type 2 alveolar cells do? What do they look like?
Cuboidal (septal) cells
- secrete surfactant
What do alveolar macrophages do? What is another name for them?
Engulf foreign particles in the lungs
- also called dust cells
How thick is the endothelium of the capillaries and the alveolar epithelium combined?
- 1 - 1.5 MICRO meters
- allows for optimal diffusion of oxygen and carbon dioxide