structure and function of the airways

Question 1

what does the trachea divide into

Answer 1

2 main bronchi

Question 2

what do the 2 bronchi divide into

Answer 2

2 more bronchi

Question 3

what is the process of bifurcation called

Answer 3

dichotomous branching

Question 4

what provides mechanical stability in the trachea

Answer 4

C shaped hyaline rings

Question 5

how is the cartilage structured around the bronchi

Answer 5

actual rings of cartilage

Question 6

where does gas exchange occur

Answer 6

alveolar ducts

Question 7

what is the name of bronchioles that have no cartilage

Answer 7

terminal bronchioles

Question 8

where are alveolar ducts found

Answer 8

respiratory bronchioles

Question 9

describe type 1 cells

Answer 9

very thin, flat delicate barrier (facilitates gas exchange)

covers 95% of the surface

Question 10

describe type 2 cells

Answer 10

replicate to replace type 1 cells 
greater in number than type 1 cells but only cover 5% of surface 
secrete surfactant (reduces surface tension) antiproteases

Question 11

what is xenobiotic metabolism

Answer 11

metabolise obnoxious chemicals that may enter airways

Question 12

a basic function of the respiratory airways is to act as conduit pipes to…

Answer 12

conduct O2 to the alveoli
conduct CO2 out of the lung
gas exchange

Question 13

basic functions of the respiratory airways is facilitated by…

Answer 13

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

Question 14

what is the pharynx

Answer 14

a common passageway for foods, liquids and air

Question 15

what does the conchae do

Answer 15

highly vascular

contributes to warming and humidification of intra nasally inhaled air

Question 16

what do nasal hairs do

Answer 16

filters out large particles

Question 17

where are the submucosal glands

Answer 17

embedded in airways smooth muscle

Question 18

what happens when smooth muscle contracts

Answer 18

it narrows down airway and maybe presses against gland to squeeze out mucus

Question 19

where does the produced mucus go

Answer 19

into the airway lumen

Question 20

what do ciliated cells do

Answer 20

move/beat/waft mucus to the back of the throat to swallow

Question 21

what other cells also produce mucus

Answer 21

goblet cells

Question 22

what are some lining cells types

Answer 22

ciliated
intermediate
brush
basal

Question 23

what are some contractile cells types

Answer 23

smooth muscle (airway, vasculature)

Question 24

what are some secretory cells types

Answer 24

goblet (epithelium)
mucous
serous (glands)

Question 25

what are some connective tissue cell types

Answer 25

``` fibroblasts interstitial cell (elastin, collagen, cartilage) ```

Question 26

what are some neuroendocrine cell types

Answer 26

nerves ganglia neuroendocrine cells neuroepithelial bodies

Question 27

what are some vascular cell types

Answer 27

``` endothelial pericyte plasma cell (and smooth muscle) ```

Question 28

what are some immune cell types

Answer 28

``` mast cell dendritic cell lymphocyte eosinophil macrophage neutrophil ```

Question 29

what do mucin granules contain

Answer 29

mucin in a highly condensed form

Question 30

what happens to mucin granules upon a stimulus

Answer 30

upon a stimulus > mucin granules move towards the apical surface (top surface of the cell) > fuse with apical surface and release mucus onto airway surface

Question 31

what do mucous cells secrete

Answer 31

mucus :))))

Question 32

what do serous cells secrete

Answer 32

antibacterial enzymes (eg. lysozme)

Question 33

what do glands secrete

Answer 33

water and salts (eg. Na+ and Cl-)

Question 34

what do cilia contain (structure)

Answer 34

apical "hooks" - engage with mucus axoneme - microtubules cell membrane "anchoring" proteins (intracellular) an efficient structure which moves cilia, axonemes slide over each other pushing cilium from one side to the other

Question 35

what rhythm is the way cilia beats

Answer 35

metachronal

Question 36

describe the way cilia beats

Answer 36

different fields of cilia one field beats on the forward stroke and then the recovery stroke when the first field is on the recovery stroke, the second field is on the forward stroke etc and that way it is able to beat

Question 37

what are the functions of airway epithelium

Answer 37

secretions of mucins, water and electrolytes, components of mucus (+plasma, mediators) movement of mucus by cilia - mucociliary clearance physical barrier production of regulatory and inflammatory mediators

Question 38

what are some examples of regulatory and inflammatory mediators

Answer 38

- nitric oxide (NO - via nitric oxide synthase NOS) - carbon monoxide (CO - via heme oxygenase HO) - arachidonic acid metabolites (eg prostaglandins via COX) - chemokines (eg GM-CSF) - proteases

Question 39

how to test for NOS

Answer 39

brown staining? | produces NO - contributes to ciliary beats

Question 40

what does airway smooth muscle contribute to

Answer 40

structure, tone and secretion

Question 41

how does airway smooth muscle contribute to tone

Answer 41

airway calibre - contraction and relaxation

Question 42

how does airway smooth muscle contribute to secretion

Answer 42

mediators cytokines chemokines bacterial products and cytokines act on smooth muscle > producing more NO/prostaglandins/cytokines/chemokines/adhesion molecules > recruitment of other inflammatory cells into airways

Question 43

how does airway smooth muscle contribute to structure

Answer 43

hypertrophy | proliferation

Question 44

what kind of systemic circulation exists in airway vasculature

Answer 44

tracheo-bronchial circulation

Question 45

how much of cardiac output does the tracheo-bronchial circulation take

Answer 45

1-5% but high perfusion

Question 46

how much blood flow to airway mucosa is there?

Answer 46

100-150 mL/min/100g of tissue | among highest to any tissue

Question 47

what do bronchial arteries arise from

Answer 47

sites on aorta, intercostal arteries and others

Question 48

what does blood return to tracheal circulation by

Answer 48

systemic veins

Question 49

where does blood return from bronchial circulation to both sides of the heart by

Answer 49

bronchial and pulmonary veins

Question 50

what lies underneath the epithelium surface

Answer 50

subepithelium microvascular network | plexus of arteries, capillaries and veins supplying epithelium and submucosa with nutrients and oxygen

Question 51

what are some theoretical functions of the tracheo-bronchial circulation

Answer 51

- 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 or bad depending on drug) - supplies airway tissue and lumen with inflammatory cells - supplies airway tissue and lumen with proteinaceous plasma (plasma exudation - leakage of plasma)

Question 52

what are controls of airway function

Answer 52

nerves regulatory and inflammatory mediators proteinases/proteases reactive gas species

Question 53

examples of nerves involved in control of airway function

Answer 53

parasympathetic (cholinergic) sympathetic - adrenergic sensory

Question 54

examples of regulatory and inflammatory mediators involved in control of airway function

Answer 54

histamine arachidonic acid metabolites (eg prostaglandins, leukotrienes) cytokines chemokines

Question 55

examples of proteinases/proteases involved in control of airway function

Answer 55

neutrophil elastase

Question 56

example of reactive gas species involved in control of airway function

Answer 56

O2- and NO

Question 57

can the airway contract and relax

Answer 57

yes

Question 58

what does adrenaline do to the airway

Answer 58

relaxes the airway - opens up airway

Question 59

what does the neural pathway do to the airway

Answer 59

also opens up the airways - NO gas produced > caused airway to relax and open

Question 60

do we have a sympathetic system to open up our airways

Answer 60

no

Question 61

can cells produce more than one mediator and can they do more than one thing

Answer 61

yes

Question 62

what are some respiratory diseases

Answer 62

``` asthma COPD CF - all of which are common conditions airway inflammation, obstruction and remodelling ```