Lecture 15: LRT Flashcards
What are the functions of the lower respiratory system?
- Conducts air to/from the site of gas exchange
- Completes cleaning, warming and humidifying of air
- Provides a barrier between the air and blood, and a large surface area for gas exchange
What and where is the larynx and what structure for swallowing can be found there?
- Passage of air only
- Anterior to esophagus, From the hyoid bone to the trachea.
- Cartilages protect and maintain an open airway (patent)
- Structure = Epiglottis which closes over the airway when swallowing
What folds can be found in the larynx?
Vocal folds
* ‘True’ vocal cords
* Passing air causes vibrations = sound waves
* Used for normal phonation
* Testosterone affects cartilage and muscle, resulting in longer, thicker folds = deeper voice
Vestibular folds
* ’False’ vocal cords
* Superior to vocal folds
* Prevent foreign object entry to the glottis
* Can produce very deep sounds
What are the anatomical structures (cartilages) of the larynx? (Superior to inferior)
The epiglottis which is attached to the hyoid bone
Thyroid cartilage including the Laryngeal prominence (Adam’s apple)
The Cricoid cartilage (complete ring of cartilage)
Finally the Tracheal cartilage (bands of cartilage that create a horseshoe shape around the trachea)
All these cartilages ensure the airway remains patent
What is the glottis?
The voice box
What and where is the trachea? What type of epithelium? What allows this structure to strech?
Is the wind pipe that leads to the lungs
- Anterior to esophagus ,Between the larynx and primary
bronchi
Lined with respiratory epithelium
Also has Many elastin fibres in lamina propria & submucosa which allows for some stretch
Name the muscle that connects the C shaped cartilage in the Trachea, what type of muscle and its function:
The band of smooth muscle that connects the trachea cartilage is the trachealis
The trachealis contracts for coughing
What is the mucociliary escalator?
- Mucus from goblet cells and mucous glands coat surface of epithelium
- Debris becomes trapped
- Cilia move this mucus to pharynx (acting like an escalator up the trachea) allowing the debris to be swallowed and helps maintain a clear airway
Where is the base and apex of the lungs? What is the costal surface of the lungs?
A bit different to the heart, the base of the lungs is the more obvious inferior or bottom part of the lung with the apex being the superior or top of the lung near the clavicles
The costal surface of the lungs is the lateral surface that lies against the ribs
Do both lungs have 3 lobes?
No
The right lung has 3 lobes
The left lung has 2 lobes (needs to make space for heart)
What is the name of where bronchi & blood
vessels enter the lungs?
The Hilum
List the bronchial tree:
- Trachea
- Primary bronchi
- Secondary (lobar) bronchi
- Tertiary (segmental) bronchi
- Bronchioles
- Terminal bronchioles
Describe the cartilage and epithelial tissue and muscle in the trachea:
- Respiratory epithelium
- C-shaped cartilage rings
- Trachealis muscle at posterior
Describe the cartilage, epithelial and muscle tissue in the Primary Bronchi:
- Respiratory epithelium
- Cartilage and smooth muscle rings complete
Describe the cartilage and epithelial tissue in the Secondary and Tertiary Bronchi:
- Respiratory epithelium starts to decrease in height, goblet cell numbers reduce
- Cartilage plates
Describe the cartilage, epithelial and muscle tissue in the Bronchioles:
- Cuboidal epithelium
- No cartilage but thick smooth muscle for bronchoconstriction/dilation
What do terminal bronchioles supply?
Each supplies a pulmonary lobule
What are pulmonary lobules?
- Pulmonary lobules made of many alveoli (air sacs)
arranged like bunches of grapes (pocket like structures, open at one side to allow air into alveoli) - ~150 million alveoli per lung
- Most of lung volume
- Enormous surface area
- External surface of alveoli covered in fine network of pulmonary capillaries
What are the two types of Pneumocytes (lung epithelial cells)? What are there functions?
Type I simple squamous
* Forms the respiratory membrane/blood-air barrier
with capillary wall and shared basement membrane
Type II simple cuboidal
* Scattered amongst Type I
* Secrete surfactant, a complex lipoprotein (phospholipid) that reduces the surface tension of the alveolar fluid, this helps maintain alveolar structure and efficient gas exchange
Do the alveoli have defense mechanisms?
It has Roaming macrophages that removes debris that makes it to alveoli
What structures form the respiratory membrane (blood air barrier)?
Alveolar cell layer, fused basement membrane, capillary epithelium
Which of these is NOT associated with the respiratory
membrane?
A. Capillary endothelium
B. Simple squamous epithelium
C. Type 2 pneumocytes
D. Fused basement membrane
C
Whilst Type 2 pneumocytes are found in the alveoli, they are not involved in the thin barrier of gas exchange itself.
Which cells remove debris from the alveoli?
A. Pseudostratified ciliated columnar epithelium
B. Goblet cells
C. Type 2 pneumocytes
D. Macrophages
D
Roaming macrophages
What is the largest cartilage of the larynx?
Thyroid cartilage
