Structure And Function of the Airways

Question 1

What is meant by dichotomous branching?

Answer 1

Where each part of the bronchi splits into two

Question 2

What does the cartilage around the bronchi provide?

Answer 2

Mechanical stability

Question 3

What is the main unbranched part of the airway called?

Answer 3

Trachea

Question 4

What is the first branch of the trachea called?

Answer 4

Primary bronchus

Question 5

What is the carina?

Answer 5

A ridge at the base of the trachea (windpipe) that separates the openings of the right and left main bronchi (the large air passages that lead from the trachea to the lungs).

Question 6

What is an alveolar duct?

Answer 6

Ducts that connect the alveolar sacs to the bronchioles

Question 7

Do the respiratory bronchioles contain cartilage?

Answer 7

no - they are non-cartilaginous

Question 8

What do Type II Pneumocytes secrete and why?

Answer 8

Surfactant - in order to reduce surface tension

Question 9

What happens to Type II cells if Type I cells become damaged?

Answer 9

They form type 1 cells

Question 10

What do the anti-proteases produced by Type 2 pneumocytes do?

Answer 10

They degrade foreign proteases which may have entered into the airways

Question 11

Which type of alveolar cell is involved in xenobiotic metabolism?

Answer 11

Type 2

Question 12

Describe the structure of Type 1 alveolar cells?

Answer 12

They are thin, and very flat that form a barrier between alveolus and capillaries

Question 13

What percentage of the alveolar surface do type 1 cells cover?

Answer 13

95%

Question 14

What percentage of the alveolar surface do type 2 cells cover?

Answer 14

5%

Question 15

Are there more type 1 or type 2 alveolar cells?

Answer 15

Type 2

Question 16

What are the two basic functions of the respiratory airway?

Answer 16

Conducting oxygen to the alveoli and conducting carbon dioxide out the lungs

Question 17

What are the three things which facilitate the efficient gas exchange?

Answer 17

• Mechanical stability from cartilage
• Control of calibre from smooth muscle
• Protection and cleaning to remove foreign particles

Question 18

What are the three regions of the pharynx?

Answer 18

Nasopharynx, oropharynx and laryngopharnx

Question 19

What is the pharynx?

Answer 19

A common passageway for food, liquids and air

Question 20

What do the conchae found in the nose do?

Answer 20

They contribute to the warming and humidification of intra-nasally-inhaled air

Question 21

Why must the air be warmed before being breathed in?

Answer 21

Cool air damages the alveoli

Question 22

What property of the conchae makes them able to humidify nasally inhaled air?

Answer 22

They are highly vascular

Question 23

What filters out large particles from nasally inhaled air?

Answer 23

Nasal hairs

Question 24

What is the main function of the goblet cells?

Answer 24

To produce mucus

Question 25

What are the 7 types of airway cell types?

Answer 25

``` Lining cells Contractile Secretory Neuroendocrine Connective tissue Vascular Immune ```

Question 26

What is contained within the granules found in the goblet cells?

Answer 26

Mucin

Question 27

Why do the cillia contain many mitochondria?

Answer 27

They need ATP to power their movement

Question 28

What happens after the granules recieve a stimuli tht they need to secrete their mucin?

Answer 28

The secretory cells take on alot of water, causing the granules to expand and release their mucus

Question 29

What part of the granule attracts the large volume of water?

Answer 29

The glycans

Question 30

What type of secretion do mucins show?

Answer 30

Constituitive

Question 31

What can stimulate mucin secretion?

Answer 31

Dust and smoke

Question 32

What is mucocilliary clearance?

Answer 32

The process by which mucus is swept by the cilia of the respiratory epithelium and propelled out the lungs and into the pharynx which results in the removal of debris and pathogens from the airways

Question 33

What do mucous cells in the airways secrete?

Answer 33

Mucous

Question 34

What do serous cells in the airways secrete?

Answer 34

Anti-bacterial enzymes like lysozyme

Question 35

What is the 9+2 arrangement?

Answer 35

Refers to how the microtubules are arranged in the cillia Helps the cilia to move rhythmically

Question 36

How many cilia are there per ciliated cell?

Answer 36

Approx 200

Question 37

What is the name given to the rhythm which cilia move by?

Answer 37

Metachondral rhythm

Question 38

What does nitric oxide synthase do?

Answer 38

produces nitric oxide

Question 39

What does nitric oxide do?

Answer 39

Interacts with the calcium ions to facilitate the beating of the cilia

Question 40

What is the purpose of smooth muscle in the airways?

Answer 40

So that it an contract to stop accidentally inhaled particles from going to far down which could result in choking - contraction means it can be coughed up

Question 41

What does the smooth muscle in the airways secrete?

Answer 41

Mediators, cytokines and chemokines

Question 42

What are some bronchoconstrictor mediators that are released from mast cells?

Answer 42

Histamine, cys-LTs and PGD2

Question 43

what are mitogens?

Answer 43

Peptides that induce cell division

Question 44

What do fibrotic mediators do?

Question 45

Thicken the tissue

Question 46

What is the blood flow levels to the airway mucosa?

Answer 46

100-150mL/min/100g

Question 47

Where do bronchial arteries arise from?

Answer 47

Many sites on the aorta and intercostal arteries

Question 48

How does the blood return from tracheal circulation?

Answer 48

Via systemic veins

Question 49

How does blood return from bronchial circulation?

Answer 49

Via bronchial and pulmonary veins

Question 50

What are the function of the tracheo-bronchial circulation?

Answer 50

- gas exchange - warming and humidification of air - clears inflammatory mediators - clears inhaled drugs - supplies airways tissue with inflammatory cells and proteinaceous plasma

Question 51

What is plasma exudation?

Answer 51

The leak of plasma into the airway tissue and lumen

Question 52

What are the four mechanisms of the control of airway function?

Answer 52

Nerves Proteases Reactive gas species eg NO Regulatory and inflammatory mediators

Question 53

What type of control is the airway function under?

Answer 53

Parasympathetic

Question 54

What effect does nitric oxide gas have on the smooth muscle in the airway?

Answer 54

It causes it to relax

Question 55

What is the predominant parasympathetic neurotransmitter in the airway?

Answer 55

Acetylcholine

Question 56

What does acetylcholine regulate?

Answer 56

Bronchoconstriction and mucus secretion

Question 57

How many mediators do regulatory-inflammatory cells produce?

Answer 57

They can produce more than 1

Question 58

What are the regulatory-inflammatory cells which are found in the airways?

Answer 58

Eosinophils, Neutrophils, Macrophages, Mast cells and T Cells

Question 59

What are the functions of he regulatory-inflammatory cells found in the airways?

Answer 59

``` Contraction and relaxation of smooth muscle Secretions Plasma exudation Neural modulation Chemotaxis Remodelling ```

Question 60

What percentage of the population suffers from ashtma?

Answer 60

5%

Question 61

What event is common with asthma, COPD and cystic fibrosis?

Answer 61

An increase in airway inflammation

Question 62

Why is it helpful for surfactant to be released by the alveolar cells?

Answer 62

Surfactant helps to create a moist surface for gas exchange to occur over as it is easier for oxygen to diffuse across the alveolar membranes when dissolved in a liquid

Question 63

How does alveolar surfactant ensure that all the alveoli inflate at roughly the same time?

Answer 63

When the alveoli inflate with air, the surfactant becomes spread out. Smaller alveoli have more surfactant per area which reduces surface tension and allows faster inflation; eventually they all inflate at the same time

Question 64

What is xenobiotic metabolism?

Answer 64

The metabolism of Nox-ous chemicals which might get into the airways