Transcript Autonomic Nervous System 1

Autonomic Nervous System
Dr Dileep Verma
Associate Professor
Deptt of Physiology
KGMU
Lecture-1 :Topics
Autonomic Nervous System (ANS):
• Introduction
• Divisions
• General Organization
• Neurons of ANS
Learning Objectives
• Difference between Somatic & ANS
• Autonomic nervous system:
- Anatomical Organization
- Functional importance
Autonomic Nervous System
Autonomic nervous system (ANS)
• Innervates organs whose functions are not
usually under voluntary control
• Effectors of ANS are Cardiac muscle
 Smooth muscles and
 Glands.
• Effectors are part of visceral organs and
blood vessels.
Organization of Nervous system
Organization of Nervous system
A Comparison of Somatic and Autonomic
Function
A Comparison of Somatic and Autonomic
Function
One neurons in the
efferent pathway.
Its cell body in gray
matter of spinal cord.
Innervates the Muscle
fibers
Always Excitatory
Two neurons in the
efferent pathway.
 1st neuron has its cell body
in gray matter of brain or
spinal cord.
• Preganglionic neuron.
 Synapses with 2nd neuron
within an autonomic
ganglion.
• Postganglionic neuron.
Excitatory/Inhibitory
A Comparison of Somatic and Autonomic
Function
Higher levels of autonomic control
Activity of the ANS is controlled by
following centers • Higher centers
Cerebral cortex
Limbic system
• Hypothalamus
• Medullary centers
• Spinal centers
Autonomic Nervous System
• Preganglionic autonomic fibers originate in
 Midbrain
Hindbrain
 Spinal cord.
• Autonomic ganglia are located in
 Head
 Neck
 Abdomen.
• Postganglionic autonomic fibers arises from
ganglia & innervate the target tissue
Autonomic Nervous System
• Preganglionic fibers are Myelinated
Type B fibers
• Postganglionic fibers areMyelinated
Type B fibers
• Autonomic nerves release NT that may be
stimulatory or inhibitory
Visceral Effector Organs
• Involuntary effectors are somewhat
independent of their innervations
Smooth muscles maintain resting tone in
absence of nerve stimulation
Denervation hypersensitivity Damage to autonomic nerve makes its target tissue more
sensitive than normal to stimulating agents.
Cardiac and many smooth muscles can
contract rhythmically in absence of nerve
stimulation
Divisions of the ANS
•
ANS has two divisions1. Sympathetic nervous system
2. Para-sympathetic nervous system
 Both have preganglionic neurons that
originate in CNS.
 Both have postganglionic neurons that
originate outside of the CNS in ganglia.
Autonomic Nervous System
Neurons of ANS
• The Neuron cell is the “functional unit” of
the nervous system (Neurone is the official
UK spelling)
• Neurons are highly specialised cells which
can carry electrical impulses along their
membranes
• Neurons can also communicate with other
neurons across synapses by chemicals
called neurotransmitters
Motor Neuron:
1.Autonomic ganglia are:
A.
B.
C.
D.
Cholinergic
Adrenergic
Noradrenergic
Dopaminergic
2.Head ganglion of autonomic nervous
system is:
A.
B.
C.
D.
Thalamus
Hypothalamus
Superior cervical ganglion
Stellate ganglion
3.What percentage of fibers in an average
skeletal nerves nerve are sympathetic ?
A.
B.
C.
D.
08
20
40
60
4.True regarding autonomic system isA. High centre of integration is medulla.
B. Conduction in autonomic fibres is same as in
somatic motor fibres.
C. Preganglionic parasympathetic fibres are more
lengthy.
D. Ratio of preganglionic and postganglionic
fibres is 20:1
5.ANS is also called:
A.
B.
C.
D.
Vegetative nervous system
Efferent visceral nervous system
Involuntary nervous system
All of the above