Physiology transition Flashcards
respiration is modified by inputs from where
pons
respiratory rhythm is generate where
medulla
where are central chemoreceptors found
near surface of medulla
what do central chemoreceptors respond to
concentration of H+ in CSF
where are peripheral chemoreceptors found
aortic and carotid bodies
what do peripheral chemoreceptors do
sense tension of CO2, O2 and H+ concentration in blood
where are stretch receptors found
bronchi and bronchiole walls
what guards against hyperinflation
Hering-Breur reflex
when are J receptors stimulated and what do they do
stimulated by Po capillary congestion + oedema, also Po emboli
results in rapid shallow breathing
what do baroreceptors do
increase ventilatory rate in response to decrease BP
what is the most potent stimulant of respiration in normal people
hypercapnia
when is the hypoxic drive stimulated
<8.0kPa PO2
how does hypercapnia generate H+
through central chemoreceptors
how is the hypoxic drive stimulated
peripheral chemoreceptors
how do peripheral chemoreceptors adjust for acidosis
addition of non-carbonic acid H+ to blood
stimulation by H+ causes hyperventilation and increased elimination of CO2 (acid)
muscles involved in inspiration
diaphragm major - C3/4/5
external intercostals lift ribs and move sternum out
accessory muscles - SCM, scalenus
three pressures involved in gas exchange
atmospheric - 760
intra-alveolar - 760
intra-pleural - 756
forces keeping alveoli open
transmural pressure gradient
surfactant
alveolar interdependence
forces promoting alveolar collapse
elasticity of stretched pulmonary connective tissue fibres
alveolar surface tension
airway resistance equation
F = deltaP/R
what is the primary determinant of airway resistance
Radius of the airway
para/sympathetic effects on airway
para - bronchoconstriction
symp - bronchodilatation
what is compliance
measure of effort going into stretching/distending the lungs
less compliant = more work
how much of total energy is usually expended on breathing
3%
