6.4: Structure and function of the airways

Question 1

What is dichotomous branching

Answer 1

Division 2:2:2

Question 2

Example of dichotomous branching in airway system

Answer 2

Trachea to bronchi then two smaller bronchi

Question 3

Mechanical stability of lungs

Answer 3

C shaped cartilage in trachea
More cartilage in bronchi

Question 4

Where does gas exchange occur in the lungs

Answer 4

Alveoli

Question 5

What cells are inside the alveoli

Answer 5

Macrophages
Type 1 cells
Fibroblasts

Question 6

Characteristics of Type 1 cells

Answer 6

Very thin -95% of alveolar surface covered
Delicate barrier facilitating gas exchange

Question 7

Characteristics of type 2 cells

Answer 7

Replicate to replace type 1 cells
Secrete surfactant
Xenobiotic metabolism
Greater in numbers but only cover 5% of surface

Question 8

Functions of pipes in the airway

Answer 8

Conduct O2 to alveoli
Conduct CO2 out of lung

Question 9

Airway pipes are facilitated by

Answer 9

Mechanical stability (cartilage)
Control of calibre (smooth muscle)
Protecting and cleansing

Question 10

Division of nasal passages

Answer 10

Conchae
Pharynx

Question 11

Characteristics of nasal conchea

Answer 11

Highly vascular, contribute to humidification of intra-nasally-inhaled air

Question 12

Function of nasopharynx

Answer 12

Common passageway for food, liquids, air

Question 13

Mucus ciliary transport

Answer 13

Smooth muscle contracts and causes mucus out of the Submucosal gland
Goblet cells produce mucus which lines cilia
Forms first line of defence against infection- traps pathogens

Question 14

Main cell types of lining cells

Answer 14

Ciliated
Intermediate
Club
Brush
Basal

Question 15

Main cell types of contractile cells

Answer 15

Smooth muscle

Question 16

Main cell types of secretory cells

Answer 16

Goblet, mucous, serous (glands)

Question 17

Main cell types of neuroendocrine

Answer 17

Nerves
Ganglia
Neuroendocrine cells
Neuroepithelial bodies

Question 18

Main cell types of vascular cells

Answer 18

Endothelial, pericyte, plasma cell

Question 19

Main cell types of immune cells

Answer 19

Mast cell
Dendritic cell
Lymphocytes
Eosinophil
Macrophage
Neurtophil

Question 20

Mucous cells secrete

Answer 20

Mucus

Question 21

Serous cells secrete

Answer 21

Anti-bacterial enzymes e.g lysozomes

Question 22

Glands also secrete

Answer 22

Water and salts

Question 23

3 components of mucus

Answer 23

Mucins
Water
Electrolytes
(+ plasma, mediators)

Question 24

Mucocillary clearance is

Answer 24

Movement of muspcus by cilia

Question 25

Functions of airway epithelium

Answer 25

Physical barrier
production of regulatory and inflammatory mediators
Movement of mucus by cilia
Secretion if mucins water and electrolytes

Question 26

What 6 regulatory and inflammatory mediators does the airway epithelium secrete

Answer 26

Nitric oxide
Carbon monoxide
Arachidonic acid metabolites
Chemokines
Cytokines
Proteases

Question 27

NOS expression in human airway epithelium

Answer 27

Cilia speed up
Lots of nitric oxide synthase which produces NO

Question 28

Airway smooth muscle functions 3

Answer 28

Structure
Tone - contract and relax
Secretion - mediators, cytokines, chemokines

Question 29

How can Inflammation of the airway alter structure

Answer 29

Hypertrophy
Proliferation

Question 30

Following inflammation how does the airway smooth muscle respond

Answer 30

Produce NO, prostaglandins, cytokines, chemokines
Resulting in inflammatory cell recruitment
(Not necessarily a good thing)

Question 31

What is the airway vasculature

Answer 31

Tracheo-bronchial circulation

Question 32

Bronchial arteries arise from many sites on

Answer 32

Aorta
Intercostal arteries
And others

Question 33

Blood returns from tracheal circulation via

Answer 33

Systemic veins

Question 34

Blood returns from bronchial circulation to both sides of the heart via

Answer 34

Bronchial and pulmonary veins

Question 35

Functions of tracheo-bronchial circulation

Answer 35

(Good gas exchange)
Warming inspired air
Humidification of inspired air
Clears inflammatory mediators
Clears inhaled drugs
( supplies airway tissue and lumen with inflammatory cells)
(Supplies airway tissue and lumen with proteinaceous plasma)

Question 36

4 controls of airway function

Answer 36

Nerves
Regulatory and inflammatory mediators
Proteinases
Reactive gas specied

Question 37

Nerves controlling airway function

Answer 37

Parasympathetic - cholinergic
Sensory
(Sympathetic- cannot open up smooth muscle)

Question 38

4 regulatory and inflammatory mediators of airway function

Answer 38

Histamine
Aravhidonic acid metabolites
Cytokines
Chemokines

Question 39

Innervation of the airways (choking response)

Answer 39

Sensory nerves relay information to the brain
Cholinergic reflex - causes smoothmuscle contraction where food is stuck
Cough reflex
Adrenaline secreted and causes airway smooth muscle to relax and open airways
NO also causes smooth muscle relaxation

Question 40

3 respiratory diseases with loss of airway control

Answer 40

Asthma
COPD
Cystic fibrosis
(Airway inflammation- airway obstruction)

Question 41

How many mediators do cells produce

Answer 41

More than one mediator; which do more than one thing

Question 42

What causes the airway to relax

Answer 42

NOS-containing nerves
Adrenaline

Question 43

What precipitates lung disease

Answer 43

Loss of homeostatic control