Lecture 15: The Lower Respiratory Tract Flashcards
What are the components of the LRT?
5
- Larynx
- Trachea
- Bronchi
- Bronchioles
- Alveoli
Where does the LRT want to conduct air form/to?
The site of gas exchange
What does the lower respiratory tract do to inspired air?
Completes cleaning, warming and humidifying of air
What does the LRT provide in terms of a site for gas exchange?
(2)
- Provides a barrier between the air and blood
- Large surface area for gas exchange
The larynx is a passage for what?
Air only
Where is the larynx?
Anterior to the oesophagus from the hyoid bone to trachea
What cartilage protects and maintains an open airway?
- Cricoid cartilage
- Tracheal cartilage
What does the Epiglottis do?
Closes over the airway when swallowing
What is the Glottis?
Voicebox
What happens at the vocal folds/cords?
Passing air causes vibrations therefore sound waves
What are the vocal folds/cords used for?
Normal phonation
What does testosterone do to the vocal cords?
Affects cartilage and muscle resulting in longer and thicker folds therefore a deeper voice
What are the vocal folds/vocal cords also known as?
True vocal cords
What are the Vestibular folds also know as?
False vocal cords
Where are the vestibular folds?
Superior to the vocal folds
What is the role of the Vestibular fold?
Prevent foreign objects entering into the glottis
What can the Vestibular fold produce?
Very deep sounds
Where is the Trachea?
Anterior to the oesophagus between the larynx and the bronchi
What is the function of the trachea?
Maintain a patent airway
What is the trachea made of?
c-shaped cartilage rings where the ends are connected by a band of smooth muscle
What is the name of the smooth muscle that connects the C-shaped cartilage of the trachea?
Trachealis
What causes coughing?
Contracting of trachealis
What is the lamina propia/submucosa layers of the trachea made of?
Many elastin fibres
What is the trachea lined with?
Respiratory epithelium
What happens to debris in the trachea?
It is removed by the Mucociliary escalator to the pharynx, to be swallowed and digested
How does the mucociliary escalator work?
Mucus from goblet cells and mucous glands trap debris and cilia move it to the pharynx
How many lobes are in the right lung?
3 lobes
How many lobes are in the left lung?
2 lobes
What is the hilum?
Where bronchi & blood vessels enter the lungs
Where is the apex of the lung?
The superior region of the lungs
Where is the base of the lung?
The inferior region of the lungs
What is at the start of the bronchial tree?
The trachea
What branches off the trachea in the bronchial tree?
Primary bronchi
What branches off the primary bronchi in the bronchial tree?
Secondary (lobar) bronchi
What branches off the secondary (lobar) bronchi in the bronchial tree?
Tertiary (segmental) bronchi
What branches off the tertiary bronchi in the bronchial tree?
Bronchioles
What branches off the Bronchioles in the bronchial tree?
Terminal bronchioles
What is the Trachea lined with and made from?
2
- Respiratory epithelium
- C-shaped cartilage rings
What is the primary bronchi lined with and made from?
Lined with respiratory epithelium and made from cartilage and complete smooth muscle rings
What is the secondary and tertiary bronchi lined with and made from?
Lined with respiratory epithelium made from cartilage plates
What happens to the respiratory epithelium in the secondary and tertiary bronchi?
Starts to decrease in height and goblet cell numbers reduce
What are the Bronchioles lined with and made from?
Lined with cuboidal epithelium and made from thick smooth muscle
What causes bronchoconstriction/dilation?
Smooth muscle in the bronchioles
What do terminal bronchioles supply?
Each pulmonary lobule
What are Pulmonary lobules made of?
Many alveoli (air sacs) arranged like bunches of grapes
Roughly how many Alveoli are there per lung?
150 million
What do the Alveoli provide to the respiratory zone?
Most of the lung volume and an enormous surface area
Alveolar walls are very thin and made of what?
Simple squamous epithelium on a thin basement membrane
What are the external surfaces of alveoli covered with?
A fine network of pulmonary capillaries
What are Pneumocytes?
Lung epithelial cells
What kind of cells are type 1 Pneumocytes?
Squamous
What kind of cells are type 2 Pneumocytes?
Cuboidal
What do type 1 pneumocytes form?
The respiratory membrane/blood-air barrier with capillary wall and shared basement membrane
Where are type 2 pneumocytes?
Scattered amongst type 1 pneumocytes
What do type 2 pneumocytes secrete?
Surfactant, a complex lipoprotein
What does Lipoprotein do?
Reduces the surface tension of alveolar fluid
What do roaming macrophage do?
Remove debris that makes it to alveoli
What 3 parts make the blood air barrier?
- Alveolar cell layer
- Fused basement membrane of alveolar epithelium and capillary endothelium
- Capillary endothelium
