Autonomic Nervous System

$**Autonomic Nervous System:**$ the system for involuntary subconscious functions. It controls internal environment to maintain homeostasis.

{{Autonomic Ganglia{{

$**Autonomic ganglia:**$ the site of physiological contact between pre and post synaptic fibers.

• diversion center
• may have multiple post-ganglionic axons

}}Types of Autonomic Ganglia}}

1. Lateral/ paravertebral
2. Terminal
3. Collateral

}}Lateral/ paravertebral}}

• close to spinal cord
• sympathetic
• 3 cervical
• 12 thoracic
• 4 lumbar
• 4 sacral

}}Terminal}}

• at the wall of the organ with no or very short post-ganglionic fibers
• parasympathetic

}}Collateral/ prevertebral}}

• around the major branches of the abdominal aorta
• sympathetic

{{$Sympathetic and Parasympathetic$ Systems{{

Reciprocal and complementary relationship between sympathetic and parasympathetic system

==pre-ganglionic neurotransmitter:== Acetylcholine

==pre-ganglionic receptor:== Nicotinic receptors

]]Sympathetic]]

Thoraco-lumbar (T1-T12, L1, L2, L3)

Stress (fight and flight)

@@Degree of diversion@@: 1:32 (wide spread)

@@Neurotransmitters@@: mainly norepinephrine (NE)

@@Receptors@@: α & β receptors

<<Parasympathetic<<

Cranio-sacral (III-VII, IX, X S2, S3, S4)

Relax (rest and digestion)

^^Degree of diversion:^^ 1:9 (localized response)

^^Post-ganglionic Neurotransmitters:^^ Acetylcholine

^^Post-ganglionic Receptors:^^ muscarinic receptors

}}Relationship}}

Reciprocal and complementary relationship between sympathetic and parasympathetic system.

Example: defecation and micturition (urine expelled from the body)

External sphincter muscles are voluntarily controlled (by somatic nervous system)

==Sympathetic== :

No defecation or micturition

Relaxation of rectal muscles

Contraction of internal sphincter muscles

^^Parasympathetic^^

Defecation and micturition

Contraction of rectal muscles

Relaxation of internal sphincter muscles