the Central Cardiovascular System
Arterial baroreceptors sense and monitor blood pressure at various sites
in the cardiovascular system. They are principally located at the aortic
arch and the carotid sinus. Responses from these baroreceptors, together
with those of chemoreceptors are
transmitted to the brain.
chemoreceptors which monitor the
and pH of the blood are
located principally at the aortic body and the carotid body.
mechanoreceptive afferent fibers), as well as thermoregulatory receptors,
that initiate appropriate reflex effects on the overall cardiovascular
Additionally, skeletal muscle contraction or changes in the
composition of the extracellular fluid of tissues can activate afferent
the muscle or tissue to cause changes in
the cardiovascular system.
Sensory inputs are temporally and spatially integrated at regions that
neurons in the
space known as the
region is located at the medulla oblongata
and pons. The medullary cardiovascular center also receives inputs from
other regions of the brain, including the medullary respiratory center,
hypothalamus, and cerebral cortex. The output from the medullary
cardiovascular center feeds
sympathetic and parasympathetic
autonomic motor neurons that innervate the heart and the smooth muscle
of arterioles and veins, as well as to other brain neurons.
The autonomic nervous system consists of two principal trunks: the
sympathetic nervous system and the parasympathetic system. Stimulation
of sympathetic nerves increases the rate and force of contraction of the
heart and causes vasoconstriction which increases arterial blood pressure.
The stimulation of parasympathetic nerves, causes a decrease in arterial
The opposing effects of these two systems on blood
pressure are sensed by two
functionally different regions
medullary cardiovascular center.
These are known as the pressor and
Stimulation of the
sympathetic activation and an increase in blood pressure. Stimulation of
the depressor center results in parasympathetic activation and a decrease