1.1.5 Afterload Flashcards
Define afterload
Peak ventricular wall tension during systole, determined b y the resistance to ejection from the ventricle.
What are the effects of a reduced afterload?
Increased SV
Decreased EDV
What are the effects of an increased afterload?
Decreased SV
Increased EDV
Increased contractility
Sympathetic neverous system influence required to maintain CO
Positive inotropic effect
What physiological factors influence arterial blood pressure?
CO
TPR
(MAP=CO*TPR)
Flow =
Flow = Driving force / resistance
CO =
CO = Arterial pressure / TPR
What are the four locations of baroreceptors?
Aortic arch
L and R internal carotid arteries
L and R pulmonary arteries
R subclavian artery
what is the aortic body and where is it located?
-cluster of chemoreceptors
-located in the aortic arch
what are the three gross layers of the heart?
Tunica Interna, Media, Adventita
define the carotid sinus.
it is a widening of the common carotid artery just before the branching of the common carotid into the internal and external
what is the purpose of the carotid sinus?
allows the baroreceptor reflex.
describe how the carotid sinus allows the baroreceptor reflex to be carried out?
↑ artery pressure
↑artery diameter
↑elastic conversion of tunica media
Stretch of baroreceptor endings (adventitia)
Mechanicalo distortion of nerve endings = action potential = ↑impulse in carotid sinus nerve
what does the baroreceptor reflex cause to happen in the heart and to systemic vasculature?
↓ HR
vasodilation
↓TPR = ↓MAP
Metaboilic factors affecting arteriolar radius
O2
(↓O2 = weaker basal tone = vasodilation)
Phosphate ions
pCO2
lactate
K+
osmolality
Neural factors affecting arteriole radius
sympathetic stimulation (vasoconstriction via 𝛂-adrenoreceptors)
𝛃-adrenoreceptors (cause vasodilation)
