4- Coronary, Pulmonary, and Cerebral Circulations Flashcards
supplies the posterior left ventricle and right ventricel
right coronary a.
supplies anterior LV
anterior descending a.
supplying lateral LV free wall
left circumflex a.
“extravascular compression” aka phasic blood flow
proximity of inner network of vessels to the blood volume of the ventricular chamber alters the distribution supply
blood flow through the coronary circuit is high…
during diastole
why are left subendocardial cesels more subject to ischemic injury than right
the left heart is subject to musch greater stree and compressive forces
stretch activated ion channels respond to pressure changes directly
myogenic mechanism
changes in teh generation and release of by-products of cardiac work
metabolic mechanism
“adenosine hypothesis”
adenosine released after depletion of ATP in cardiac myocytes diffuses to nearby vascular smooth muscle cells and binds to adenosin receptor, activating an intracellular signal cascade to elicit vasodilation
capacity of the vasculature to respond to a vasodialtory stimulus
coronary reserve
biphasic effect of sympathetic stimulation on coronary blood flow
- constrict (due to activation of alpha adrenergic receptors)
- vasodilation (indirect effect on oxygen demand through beta adrenergi receptors)
second is the greater effect
how are pulmonary vessels different than their systemic counterparts
more elastic and less smooth muscle (in order to accommodate entire CO )
do pulmonary vessels have a myogenic response?
NO
does hypoxic vasoconstriction happen anywhere but the lungs?
NO because the lungs don’t want to ‘waste’ ventilation
elsewhere in the body hypoxia –> greater perfusion
supplies most of the forebrain
internal carotids
supplies brain stem, cerebellum, occipital lobe and part of thalamus
vertebral aa.
supplies occipital lobe and the choroid plexuses of the 3rd and 4th lateral ventricles and lower temporal lobe
posterior cerebral a.
supplies deep structures of brain
middle cerebral a.
supplies the frontal lobe and medial regions of cortex
anterior cerebral a.
circumventricular organs
brain structures outside the blood-brain barrier
- subfornical organ
- organ vasculosum of lamina terminalis
- area postrema
- neurohypophysis
important region in thrist response
SFO contains sensory machinery to taste peripheral circulation
detecting ion balance
OVLT
the heart is perfused primarily during what phase of the cardiac cycle?
ventricular diastole
difference between passive movement due to pressure and the autoregulatory curve (active maintenance of tension in vessel) =
coronary reserve
what does chronic hypoxemia lead to …
increased resistance to flow which causes right ventricular hypertrophy and eventually right ventricular failure “cor pulmonale”
where does most of the brain’s blood supply come from?
80% internal carotids
