Respiratory

Question 1

What is the function of a type 1 pneumocyte?

Answer 1

responsible for O2- CO2 gas exchange 
very thin stretched out cell linking the alveolus 
susceptible to toxic insult 
cannot replicate
so will not be replaced once damaged

Question 2

What is the function of a type 2 pneumocyte?

Answer 2

synthesis and secretion of surfactant
Surfactant reduces the surface tension of the alveolus
This allows it to remain open between breaths
Surfactant also contributes to the elastic property of lungs
Smaller cells, residing in lumen of alveolus
Capable of replicating, and can do so to replace damaged type 1 pneumocytes

Question 3

What are alveolar macrophages?

Answer 3

antigen presenting cell
tissue resident macrophage
Mops up dust or microorganisms from respiratory surfaces

Question 4

What is the appearance of alveolar macrophages?

Answer 4

contain carbon-dense granules of exogenous material when filled
these are more readily observed in smokers or those who live in polluted areas
Filled macrophages exit alveoli via the blood or are coughed out (facilitated by cilia)

Question 5

What are the differences between the left and right main bronchi?

Answer 5

right main bronchus - wider, shorter and more vertical. Enters the right lung at ~ T5.

left main bronchus - smaller but longer, enters lung at T6

Foreign object more likely to be lodged in right main bronchus

Question 6

What are the cross-sectional structures of a bronchus?

Answer 6

Lumen
respiratory epithelium
smooth muscle layers (x2) - secrete mucus
hyaline cartilage

Question 7

How many secondary/lobular bronchi are there for each lung?

Answer 7

Right lung - 3 lobes (superior, middle and inferior) - 3 secondary/lobular bronchi
Left lung - 2 lobes (superior and inferior) - 2 secondary/lobular bronchi

Question 8

What is C-shaped cartilage and where does it reside?

Answer 8

Present in the trachea
C-shaped - because the rings are incomplete so that the trachea can be partially compressed as food travels down the oesophagus
Hyaline cartilage §

Question 9

What are terminal bronchioles?

Answer 9

Last generation of the conducting airways

These do not contain alveoli on their walls

Question 10

What are respiratory bronchioles?

Answer 10

Have alveoli on their walls
respiratory bronchioles split off into a number of alveolar ducts, which go on to become alveolar sacs
Alveolar sacs contain individual alveoli

Question 11

What are the 2 main ways by which O2 is transported in the body?

Answer 11

bound to Hb (98%)

dissolved in plasma (2%)

Question 12

What is the maximum amount of O2 that can be dissolved in plasma? Under what conditions is this possible?

Answer 12

6-7% max
Only achieved in hyperbaric chambers where the O2 partial pressure exceeds atmospheric pressures
Note: O2 is the plasma is highly reactive and may interact with HCO3- buffer system

Question 13

What is a pulmonary shunt?

Answer 13

this occurs due to collapsed alveoli and inefficient gas exchange
Some Hb will remain deoxygenated even after passing the alveoli

Question 14

How much is considered normal for pulmonary shunting?

Answer 14

3% of cardiac output

Pathological shunting occurs due to V/Q mismatch

Question 15

What is the most common cause of bronchiectasis in adults?

Answer 15

H. influenzae

The British Thoracic Society reports Haemophilus influenza is found in up to 35% of patients with bronchiectasis