lecture 12: Lower respiratory tract

Question 1

What structures of the lower respiratory tract does air pass through on the way to the alveoli?

Answer 1

• Trachea
• Bronchi
• Bronchioles
• Alveoli ducts
• Alveoli

Question 2

What is the overall function of the LRT?

Trachea ——> Alveoli

Answer 2

• Conduct air to/from site of gas exchange
• Completes the cleaning, warming and humidification of inhaled air
• Gas exchange occurs at the alveolus

Question 3

What is the function of the trachea?

Answer 3

• Maintains an open airway for conduction of air
• Cleans, warms and humidifies inhaled air
• Cilia from the mucocillary escalatory to remove debris in the pharynx and redirect it to the stomach

Question 4

What is the structure of the trachea?

Location of the trachea?

Answer 4

• RiGID tube that extends from larynx to primary bronchus
• Cartilage = holds trachea and bronchi open so that they do not collapse
• lined with respiratory mucosa
  Located: anterior to the oesophagus, trachealis muscle is posterior
• Trachea branches into the left and right main bronchus,

Question 5

Where are the lungs situated?

Where is the apex?
Where bases?
Where is the costal surface?
Where is the hilum?

Answer 5

Situated in pleural cavities

apex - superior region: near clavicle
base - inferior region : sits on diaphragm
costal surface - outer surface: against ribs
hilum - medial aspect

Question 6

How many lobes and fissures do the right and left lung have?

What is the reason for the difference in lobes?

Answer 6

Right lung = 3 lobes and 2 fissure
Left lung = 2 lobes and 1 fissure

Left has only 2 lobes due to the presence of the heart

Question 7

What are the main features of the alveoli?

Answer 7

• thin membrane in close proximity to blood vessels which enable gas exchange with blood
• walls of alveoli are composed of a single layer of thin, flattened epithelial cells udelain by a thin basal lamina
  aveoli = site of gas exchange & account for most of the volume in the lungs, have a large SA
  Alveoi are found in Alveolar sacs

Question 8

What is the structure of the Alveolus?

Answer 8

• Pocket-like - open at one side
• Dense capillary network covering
  Contain pneumocytes - lung epithelial cells
• Type 1 = simp.e squamous epithelium which form the wall of the alveoli
• Type 2 = cuboidal cells which are found throughout the alveoli and their function is to recuse the surface tension by secreting surfactant