PSIO 532 Study Guide - Midterm Guide: Vasomotor Center, Baroreceptor, Vasomotor
PSL – Cardiovascular System
Baroreceptors – Stretch Receptors
Baroreceptors are basically stretch receptors. As blood
pressure increases, the baroreceptors are stimulated. Each
baroreceptor displays three characteristics:
THRESHOLD→ As blood pressure increases from very low
levels, baroreceptors remain silent until the threshold is
reached.
MAXIMAL SENSITIVITY → A range of blood pressures
above threshold wherein the receptors are highly
responsive to changes in pressure. The slope of the relationship between baroreceptor nerve
activity is high.
SATURATION → As blood pressure rises, baroreceptor nerve activity ceases to increase further.
The baroreceptors relay their information up to the vasomotor center (controls sympathetic
activity). Different individual baroreceptor afferents have different thresholds, sensitivities
(slopes) and different points of saturation. At low pressure,
there is no baroreceptor nerve activity (the efferent nerves are
not firing). Once pressure rises the threshold, the baroreceptor
nerve activity begins (whole nerve activity increases). For the
most part, this will increase linearly, but then at the end (too
much pressure), there is a plateau (saturation). At maximal
sensitivity (midrange of pressure) is where we can relay a lot of
information about the arterial blood pressure; slope of the
whole nerve activity is the highest → in this area, the baroreceptors are able to relay
information regarding the small changes in blood pressure. Once pressure gets too high, we
reach saturation, we get no more BR nerve activity (the BR cannot relay anymore information
about the changes in blood pressure).
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Document Summary
As blood pressure increases, the baroreceptors are stimulated. Threshold as blood pressure increases from very low levels, baroreceptors remain silent until the threshold is reached. Maximal sensitivity a range of blood pressures above threshold wherein the receptors are highly responsive to changes in pressure. The slope of the relationship between baroreceptor nerve activity is high. Saturation as blood pressure rises, baroreceptor nerve activity ceases to increase further. The baroreceptors relay their information up to the vasomotor center (controls sympathetic activity). Different individual baroreceptor afferents have different thresholds, sensitivities (slopes) and different points of saturation. At low pressure, there is no baroreceptor nerve activity (the efferent nerves are not firing). Once pressure rises the threshold, the baroreceptor nerve activity begins (whole nerve activity increases). For the most part, this will increase linearly, but then at the end (too much pressure), there is a plateau (saturation).
