PHAR2220 Lecture Notes - Lecture 5: Bronchial Artery, Airway Obstruction, Pulmonary Vein
TOPIC&2:&RESPIRATORY&SYSTEM:&
&
Lecture&4:&Lung&Structure&and&Airway&Diseases:&
!
Respiratory&Tract:&
!
"!Gas!exchange!–!most!important!function!
"!Airway!epithelium!continues!from!trachea!
to!alveoli!
!
Trachea:!
"!Cartilaginous!rings!–!hold!airway!open!
"!Does!not!contract!
!
Bronchioles:!!
"!Airways!that!do!not!have!cartilage!
!
Main&Divisions:&
!
Conducting:!conduct!air!into!and!out!of!lungs!
"!Cartilage!
"!Airway!smooth!muscle!
"!Respiratory!epithelium!
!
Resistance:!airway!smooth!muscle!contraction!!!
decreased!airflow!
"!Airway!smooth!muscle!
"!Respiratory!epithelium!
!
Respiratory:!gas!exchange!takes!place!
!
Bronchus&and&Bronchiole:&
!
Bronchus:!contains!cartilage!
"!Glands!secrete!mucus!!
o!Keeps!airways!moist!
"!Elastic!tissue!
"!Smooth!muscle!!
o!Contraction!!!decreased!airflow!
o!Relaxation!!!increased!air!flow!
Epithelium:!barrier!between!air!breathed!in!and!rest!of!
tissues!
!
Alveolar&Airways:&
!
"!Smooth!muscle!present!in!alveoli!
"!Large!surface!area!where!gas!exchange!can!take!
place!
!
!
!
Alveolar&–&Capillary&Interface:&
!
"!Oxygen!crosses!lipid!lining!!!basal!
laminas!(which!are!fused)!!!capillary!
endothelium!!!red!blood!cell!
!
!
!
!
!
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Pulmonary&Blood&Vessels:&
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Pulmonary!Arteries!and!Veins:!
"!Carry!blood!to!(arteries)!and!from!(veins)!the!lungs!
"!Pulmonary!veins!carry!O2!
"!Pulmonary!arteries!carry!CO2!
!
Bronchial!Arteries!and!Veins:!
"!Supply!blood!to!and!drain!from!the!airways!
"!Bronchial!arteries!carry!O2!
"!Bronchial!veins!carry!CO2!
!
"!Bronchial!odema!in!asthma!
o!Leakage!of!plasma!from!bronchiole!circulation!within!airway!wall!!!swelling!(odema)!!!
narrower!airway!!!bronchiole!obstruction!
!
Airway&Epithelium:&
!
Physical!Barrier!–!pseudostratified!columnar:!
"!Inhibits!penetration!of!inhaled!noxious!substances!!
o!Allergens,!mast!cell"derived!mediators,!particulate!matter,!irritant!molecules!
"!Prevents!access!to!submucosa!
o!Nerves,!vascular!tissue,!airway!smooth!muscle!
!
Housekeeping!Role:!
"!Cilia!beat!synchronously!to!propel!mucus!upward!towards!the!throat!
"!Mucus!and!any!adherent!particulate!matter!continually!cleared!
"!Damaged!first!in!asthma!
!
Catabolic!Metabolism:!(breakdown)!
"!Via!cytochrome!P450!system!
"!Peptide!degradation!via!neural'endopeptidase!
o!Neuropeptides,!proteins!with!airway!activity!
"!Protects!sensitive!targets!–!nerves,!muscle,!glands!
!
Anabolic!Metabolism:!(synthesis)!
"!Synthesis!of!inhibitory!mediators!–!PGE2!(prostaglandin!E2)!
"!Rich!source!of!peptides!–!endothelium!(growth!factor)!
"!Produces!pro"inflammatory!cytokines!
o!Protects!against!allergens!
Airway&Nerves:&
!
"!Excitatory!=!CONTRACTION!
"!Inhibitory!=!RELAXATION!
!
Cholinergic!(excitatory):!!!Parasympathetic!
"!Stimulation!!!release!acetylcholine!!!contraction!of!airway!smooth!muscle!via!M3!Receptors!
"!Dominant!neural!pathway!in!the!airways!
"!Major!role!in!regulating!airway!smooth!muscle!tone!and!mucus!production!
!
Noradrenergic!(inhibitory):!!!Sympathetic!
"!Noradrenaline!decrease!smooth!muscle!tone!
"!Does!not!play!a!dominant!role!below!main!bronchi!
!
Inhibitory!Nonadrenergic!Noncholinergic!(iNANC):!
"!Release!nitric!oxide!(NO)!
"!Innervates!smooth!muscle!directly!to!cause!relaxation!
!
Excitatory!Nonadrenergic!Noncholinergic!(eNANC):!
"!Release!neuropeptides!!!contraction!
o!E.g.!substance!P,!neurokinin!A!
"!Increase!airway!tone,!secretion!of!mucus!and!microvascular!leakage!
o!Capsaicin!in!pepper!spray!
!
What&is&Asthma?&
!
"!Chronic!inflammatory!disease!of!the!airways!characterised!by!bronchial!obstruction!and!airflow!
limitation!which!is!reversible,!either!spontaneously!or!with!treatment!
!
Symptoms:!Shortness!of!breath,!wheeze,!tight!chest,!cough!
!
Cause:!Allergic,!occupational,!exercise"induced,!aspirin!
!
Severity:!Mild,!moderate,!severe!
!
Economic!Impact:!
"!>!2!million!Australians!
"!1!in!6!children,!1!in!9!adults,!10%!workforce!
"!550,000!work,!1!million!school!days!in!WA!
!
Allergens&in&Asthma:&
!
Potential!allergens!include;!
"!house!dust!mite,!grass!pollen,!animal!dander,!fungal!spores!
!
Allergic!Response:!
!
1.!Early!phase!response:!
o!Dec!in!FEV1!(Forced!expiratory!volume!in!1!sec!!!higher!FEV1!=!more!you!can!exhale!=!
better!lung!function),!peak!worse!–!30"40!min,!resolves!–!2"3!hours!
o!Broncho"histamine!response!"!mast!cell"derived!histamine!and!leukotrienes!
