Myelinatedwith the conscious participation of minddirect action ,no participation of pro or postganglionic neurons.
Come from thoracic and lumbar regions of the spinal cord, and they synapse in two cord like chains of ganglia that run in parallel on each side of spinal cord.
acetylcholine, a neurotransmitter that activates nicotinic acetylcholine receptors on postganglionic neurons. Has widespread action on body as the result of preganglionic fibers synapsing many postganglionic neurons.
preganglionic fibers tend to be shorter because sympathetic ganglia are often closer to the spinal cord
Postganglionic neurons of sweat glands release acetylcholine for the activation of muscarinic receptors
Nor epinephrine varies according to the amount of stress present and will cause transient changes in heart rate and systemic arteries and veins. Epinephrine is a constant in regulating heart rate, vasoconstriction in systemic arteries and veins and vasodilation of muscles and liver.
Continually active ( in maintaining tone of vascular beds) This system with its diffused distribution of postganglionic fibers is involved in a wide array of physiologic activities but it is not essential for life.
These reactions are triggered by both direct sympathetic activation of the effectors organs and by stimulation of adrenal medulla to release epinephrine and lesser amounts of nor epinephrine
Maintains essential bodily functions, such as digestive process and elimination of wastes and is required for life.
Increase blood flow to the skeletal muscles and the heart while diverting flow from the skin and internal organs
S-inhibits secretary activity; causes vasoconstriction of blood vessels supplying glands
P-contraction smooth muscle of bladder wall; relaxes urethral sphincter; promotes voiding S-relaxation of smooth muscle of bladder wall; constricts urethral sphincter; inhibits voiding
Autonomic Nervous System
Prepared by: ANAM KHAN
Brain and spinal cord:
Receives and processes incoming
sensory information and responds by
sending out signals that initiate or modify
all the neurons and ganglia found
outside the CNS-any nerve that enters
or leaves the CNS
The main function of the PNS is to connect the
CNS to the limbs and organs, essentially
serving as a communication
relay going back and forth between the brain
and the extremities.
It is subdivided into:
Efferent Division – the neurons of which carry
signals away from the brain and spinal cord to
= Afferent division – the neurons of which bring
info from the periphery to the CNS.They provide
sensory input to modulate the function of efferent
efferent neurons are Involved in the
voluntary control of functions
Autonomic Efferent Regulates everyday
requirement of vital bodily functions without the
conscious participation of the mind.
Cell body is located
within the CNS
Cell body originating
in the ganglion
brainstem or spinal
cord and make
arise from the
X) and from the
Efferent nerve fibers
originate from nerve
cells in the lateral
gray column of the
spinal cord between
first thoracic and
has the ability to bind
with both of these receptors.
In preganglionic neurons, both
parasympathetic and sympathetic, the
release of acetylcholine binds
predominantly with nicotinic
on the postganglionic
•At the synapses within the ganglia, preganglionic
neurons release acetylcholine.
•In response to this stimulus postganglionic neurons with two important exceptions - release nor
•Activates adrenergic receptors on the peripheral
The activation of
The two exceptions mentioned above are:
postganglionic neurons of
sweat glands and
• chromaffin cells of the
The parasympathetic nervous system uses
chiefly acetylcholine (ACh) as its
Most transmissions occur in two stages:
•When stimulated, the preganglionic nerve releases
ACh at the ganglion.
•which acts on nicotinic receptors of
•The postganglionic nerve then releases ACh to
stimulate the muscarinic receptors of the target
Both always present in the blood.
Nor epinephrine varies
Epinephrine is a constant
3rd division of ANS
Works independently of CNS
of Gut ( as it
is the collection of
nerve fibers that
gastrointestinal tract ,
pancreas and gall
Modulated by both the parasympathetic and
sympathetic nervous system
and microcirculation of
Continually active to some degree
Diffused distribution of postganglionic
The changes experienced by the body during
emergencies have been referred to as the “fight
or flight” response.
essential bodily functions
Generally dominant over sympathetic system in
It usually acts to oppose or balance the
actions of sympathetic division.
P-constricts pupils ( III occulomotor)
P-decreases rate; slows and steadies
S-Increases rate and force of heartbeat
Digestive Tract Organs:
P-increases motility and amount of
secretions by digestive organs' relaxes
sphincters and allow movement of food
S-decreases activity of glands and muscles of
digestive system and constricts sphincte r;
Arrector pili muscles attached to hair follicle
S-stimulates to contract—Goosebumps
S-Epinephrine stimulates liver to release glucose
medulla cells to