Lecture 6

Question 1

What occurs in the respiratory zone?

Answer 1

Gas exchange.

Question 2

What does the respiratory zone comprise of?

Answer 2

1. Respiratory bronchioles.
2. Alveolar ducts.
3. Alveoli sacs.
4. Alveoli.

Question 3

Where does the majority of gas exchange occurs?

Answer 3

In the delicate balloon shaped alveoli. The alveoli are in contact with the capillaries. The combined distance air must travel is about 0.5microm.

Question 4

What are the majority of cells in the respiratory bronchioles?

Answer 4

Cuboidal epithelial and the club cells.

Question 5

What do club cells do?

Answer 5

Dome shaped secretory cells that can also act as stem cells to regenerate the lower airways.

Question 6

What do the club cells secretions contain?

Answer 6

Lipoproteins that prevent luminal adhesion if the airway was to collapse. It has anti-microbial properties.

Question 7

Describe Type 1 pneumocytes?

Answer 7

Squamous cells. Full of cytoplasm with a bump (nucleus sits). Bulk of gas exchange occurs here. Comprise of 95% of surface area of the alveoli.

Question 8

Describe Type 2 pneumocytes?

Answer 8

Surfactant cells, that secrete surfactant (mainly a phospholipid) which is important in reducing the surface tension in the alveoli. This reduces the work of breathing.

Question 9

Describe alveolar macrophages?

Answer 9

Wandering cells. That are occasionally in the septa as well. They are your last defence (important with heart failure).

Question 10

What is the connective tissue between the capillaries?

Answer 10

Collagen and elastin (make up the septa). This helps support the capillary entrance and the alveoli.

Question 11

What do the elastic fibres provide in the inter-alveolar septa?

Answer 11

Recoil associated with tidal breathing. They surround the bronchi and bronchioles and provide elasticity to the alveoli.

Question 12

What do the collagen fibres provide in the inter-alveolar septa?

Answer 12

Plays an important structural component to the inter-alveolar septum.

Question 13

What happens when there is an increase in collagen?

Answer 13

Fibrotic lung disease characteristic. Basically the septa will be thicker and stiffer and the diffusion distance for air will be bigger thus higher gradient of pressures.

Question 14

How many circulations are in the lung?

Answer 14

Two - pulmonary and bronchial circulation.

Question 15

Describe the pulmonary circulation?

Answer 15

This is a low pressure conducting circuit that carries deoxygenated blood to the alveoli for oxygenation which then returns to the left atrium.

Question 16

Describe the bronchial circulation?

Answer 16

This is a high pressure circulation that supplies the tissues of the conducting zone.

Question 17

Describe the flow of the pulmonary circulation?

Answer 17

Start with the pulmonary arteries which carry oxygen poor blood form the right side of the heart. Runs with airways and then you get to pulmonary capillaries, then you get pulmonary veins where they are mixed venous (oxygen has been introduced). They travel up to the hilum of the lung.

Question 18

Describe pulmonary arteries?

Answer 18

They are large and poorly oxygenated.

Question 19

Describe the systemic vessels?

Answer 19

In the walls of the airway, high pressure and much smaller (microscopic).

Question 20

Describe the function of the pulmonary circuit?

Answer 20

Conducting funciton.

Question 21

Where are the arteries in the pulmonary circuit?

Answer 21

Next to bronchi.

Question 22

Where are the veins in the pulmonary circuit?

Answer 22

In parenchyma.

Question 23

What are the pressures in the pulmonary circuit?

Answer 23

Arteries:
25-15mmHg.
Veins:
5-0mmHg.

Question 24

Describe the function of the systemic circuit?

Answer 24

Supply tissue of the lung with oxygen and remove carbon dioxide.

Question 25

Where are the arteries in the systemic circuit?

Answer 25

In ways of airways.

Question 26

Where are the veins in the systemic circuit?

Answer 26

The veins anastomose and are azygous.

Question 27

What are the pressures in the systemic circuit?

Answer 27

Arteries:
120-80mmHg to maybe 40mmHg.
Veins: