Airway structure+function

Question 1

What are bronchi split into following the trachea?

Answer 1

Secondary(Lobar) bronchus
Tertiary(Segmental) bronchus

Question 2

What is a respiratory bronchiole?

Answer 2

A region of bronchioles containing alveoli

Question 3

How do you describe the branching of the airways?

Answer 3

Dichotomous

Question 4

What leads to an alveolar sac?

Answer 4

Alveolar duct

Question 5

What are T1 and T2 alveolar cells and what are their functions?

Answer 5

T1: Thin, delicate barrier to facilitate gas exchange

T2: Replicate to replace T1 cells
-Secretes surfactant(reduces surface tension) and antiproteases
-Xenobiotic metabolism

Question 6

What is the percentage cover of T1 and T2 alveolar cells?

Answer 6

T1~95%
T2~5%(But has greater number of cells)

Question 7

By what 3 means are the functions of the airways facilitated

Answer 7

mechanical stability (cartilage)
control of calibre (smooth muscle)
protection and ‘cleansing’

Question 8

What is the pharynx and what regions is it split into?

Answer 8

Def-A common passageway for food, liquids and air
Nasopharynx
Oropharynx
Laryngopharynx

Question 9

Describe the general innervation of the nasal passage and the purpose of the nasal conchae

Answer 9

highly vascular – contribute to warming and ‘humidification’ of intra-nasally-inhaled air

Olfactory bulb branches down into nasal passage and detects smell

Question 10

Answer 10

Ciliated cell

Question 11

Answer 11

Blood vessel

Question 12

Answer 12

Goblet cell, mucus

Question 13

Answer 13

Smooth muscle

Question 14

What are the 7 main types of cells in the airway and give an example of each?

Answer 14

Lining cells - Ciliated
Contractile cells - Smooth muscle
Neuroendocrine cells - Nerve cells
Secretory cells - Goblet cells
Connective tissue cells - Fibroblast
Vascular cells - Endothelial cells
Immune cells - Mast cells
SCLIVCN

Question 15

What is the purpose of mucous and serous acini in a bronchial gland?

Answer 15

Mucous cells: Secrete mucus
Serous cells: Secrete anti-bacterial enzymes e.g lysozymes

Question 16

Answer 16

Axoneme of the cilia
(Microtubules within it)

Question 17

Roughly how many cilia are there per ciliated cell?

Answer 17

~200

Question 18

What is the structure of the axonemes inside the cilia like?

Answer 18

‘9+2’ configuration

Question 19

Answer 19

Intracellular anchoring proteins

Question 20

Answer 20

Ciliary hooks-Engage with mucus

Question 21

What are the 4 main functions of the airway epithelium?

Answer 21

-Secretions of mucus
-Movement of mucus by cilia
-Physical barrier
-Production of inflammatory/regulatory mediators

Question 22

Give some examples of inflammatory/regulatory mediators produced in the airway epithelium

Answer 22

NO, CO, Arachidonic acid metabolites, Chemokines, Cytokines, Proteases

Question 23

What is thought to be the mechanism of NO?

Answer 23

Increase the rate of ciliary beating, can be stained to show presence

Question 24

What 3 major effects do airway smooth muscle cells have on the airway and what physiological process stimulates these pathways?

Answer 24

Structure
-Controls hypertrophy+proliferation
Tone
-Controls contraction, relaxation
Secretion
-Secretes cytokines, chemokines

Inflammation promotes these pathways, especially secretion

Question 25

What is the mechanism of inflammation on airway smooth muscle cells?

Answer 25

Inflammation acts through: -Cytokines -Bacterial products 1)Activates nitric oxide synthase to produce NO 2)Activates COX to produce prostaglandins 3)Produces cytokines, chemokines and adhesion molecules

Question 26

What is the blood flow to the airway mucosa(ml/min/100g tissue)?

Answer 26

100-150mL/min/100g of tissue

Question 27

How does blood return from the tracheal circulation?

Answer 27

Systemic veins

Question 28

How does blood return from bronchial circulation?

Answer 28

Bronchial and pulmonary veins

Question 29

Give 7 functions of the tracheo-bronchial circulation

Answer 29

Good gas exchange (directly between airway tissues and blood) Contributes to warming of inspired air Contributes to humidification of inspired air Clears inflammatory mediators Clears inhaled drugs (good/bad, depending on drug) Supplies airway tissue and lumen with inflammatory cells Supplies airway tissue and lumen with proteinaceous plasma (termed ‘plasma exudation’)

Question 30

What type of innervation supplies the airways and what molecules act as neurotransmitters in those pathways?

Answer 30

Parasympathetic - cholinergic Sympathetic - adrenergic Sensory

Question 31

What 4 factors control airway function?

Answer 31

Nerves Inflammatory mediators Proteases Reactive gas species

Question 32

What is unique about the innervation of the airways in humans compared to most other mammals?

Answer 32

Human airways aren't sympathetically innervated

Question 33

Through what 2 mechanisms are the human airways able to relax?

Answer 33

Adrenaline produced by the adrenal glands NO produced by nitric oxide synthase in epithelium

Question 34

What nerve innervates the airways?

Answer 34

Vagus

Question 35

How are goblet cells stimulated to produce mucus?

Answer 35

Through vagus nerve innervation

Question 36

What are the regulatory-inflammatory cells in the airways?

Answer 36

Structural cells+ Neutrophils Macrophages Eosinophils Mast cells T-lymphocytes

Question 37

What are the ganglions present in the system innervating the airway?

Answer 37

Nodose ganglion Dorsal root ganglion

Question 38

What are some diseases that lead to a loss of airway control?

Answer 38

Cystic fibrosis COPD Asthma -*All are common conditions*