BSCI450: Modulation of Ventilation

perfusion (P)

bloodflow to alveoli

ventilation (V)

airflow to alveoli

PQ matching

amount of blood reaching alveoli ~ amount of air reaching alveoli

ventilation > perfusion

wasted air

fusion > ventilation

wasted blood

describe PQ matching with airway blockage

PCO2 increases, PO2 decreases

low PO2 strongly signals for vasoconstriction

high PCO2 weakly signals for vasoconstriction

describe PQ matching with blood vessel blockage

no blood for alveolus to exchange so levels match atmospheric

PO2 = 160 & PCO2 = 0.3

low PCO2 signals for bronchoconstriction

high PO2 weakly signals for bronchoconstriction

what blood vessel does PQ matching refer to

pulmonary arterioles

what airway does PQ matching refer to

bronchioles

high PCO2 triggers…

bronchioles

pulmonary arteries

systemic arteries

dilate

n/a

dilate

low PCO2 triggers…

bronchioles

pulmonary arteries

systemic arteries

constriction

n/a

constrict

high PO2 triggers…

bronchioles

pulmonary arteries

systemic arteries

n/a

n/a

constrict

low PO2 triggers…

bronchioles

pulmonary arteries

systemic arteries

n/a

constrict

dilate

philosophy behind PQ matching

why waste air on non-perfused alveoli?

why waste blood on non-ventilated alveoli?

flow of brain control

higher brain centers -> pontine respiratory group -> dorsal respiratory group (medulla) + ventral respiratory group (medulla)

DRG -> inspiratory muscles -> diaphragm via phrenic nerve

VRG -> pharynx, larynx, tongue to keep airways open during respiration

what is the dorsal respiratory group contained within

nucleus tractus solitarus

where does the DRG receive sensory input from

chemoreceptorsw

where is the pre-botzinger complex found

VRG

what is the function of the pre-botzinger complex

set breathing rhythm

how do opioids affect breathing

inhibit receptors on pre-botzinger complex, causing respiratory depression

where does the PRG receive sensory signals from

DRG

function of PRG

allow smooth breathing via tonic output

what happens after inspiration

inspiratory neurons stop firing to allow passive relaxation

as inspiration progresses, what happens to the number of active inspiratory neurons

increases since you need more force to overcome resistance from diaphragm =

polio

cure

kills phrenric nerve MN -> can’t drive sufficient inspiration

iron lung surrounds body in negative pressure vacuum -> lungs expand -> allows inspiration without diaphragm

breathing and emotion

key brain structure

emotions affect breathing, breathing affects emotion

pre-botzinger complex generates rhythm -> emotion modulates it and is influenced by it

reusme at slide 14