Vascular
Biology,
Structure
and
Function
37
in blood pressure. Figure
2.4.1
presents one scheme that summarizes the
overall central cardiovascular system control.
OTHER
INPUTS
'---------I
Arterlal
blood
moositlon
Lung
inflation
Somatic,
etc.
OTHER
CIRCULATORY
i
I
Csnlic
Pulmonary
DISTURBANCE
1v
HEART
AND
BLOOD
VESSELS
-*
Intnvnscular
preMurss
Arterial
cus
EFFECTORS
cangr
BARORECEPTOR
L
_______---
Fig.
2.4.1:
A
schematic illustration of the cardiovascular control system.
A
number of
negative feedback loops are seen. Various receptors monitor changes in the state
of
the
cardiovascular system, sending inputs to medullary cardiovascular center. From Randall
et al.
(1997).
2.4.2 Functions
of
the Baroreceptors
Baroreceptors are located
in
the carotid sinus and the aortic arch. There
are
two
types
of
barorecptors.
The unmyeIinated baroreceptors are
localized in the central cardiovascular system and respond to pressures
above normal and initiate reflexes to reduce arterial blood pressure. The
myelinated baroreceptors respond to blood pressures below normal and
thus protecting the cardiovascular system from prolonged reduction in
blood pressure. The carotid sinus and aortic arch perform similar
functions and differ only slightly in terms of structure.
