autonomic nervous system

components

parasympathetic, sympathetic, enteric

target tissues

cardiac, smooth, glandular tissue

what is the ans involved in

• percieved sensation

• involuntary inhibition or excitation of visceral and glandular tissue

• homeostasis

• complements the endocrine system

components of the ans

• general visceral efferent motor neurons- visceromotor fibres- target tissues

• general visceral afferent sensory neurons- enteroreceptors (chemoreceptors, baroreceptors)- viscero sensory fibres. Sensory fibres coveyed from the periphery to the cns via cranial nerves and somatic spinal nerves

• central integration centres (brain)- hypothalamus, brain stem (pons, medulla)

anatomy of the ans

2 neuron system in the periphery

1. pre-ganglionic neuron- cell body in brain or spinal cord

2. post-ganglionic neuron-cell body lies outside cns in autonomic ganglia

which is parasympathetic and sympathetic from craniosacral outflow and thoracolumbar outflow

• craniosacral- parasympathetic

• thoracolumbar- sympathetic

parasympathetic

• cranial parasympathetic outflow via:

• cranial nerves III, VII, IX AND X

• to visceral and glandular tissues of the head

• CN X - vagus nerve

• heart

• most of the GIT

• sacral outflow (S1-S3)

• caudal GIT

• urinary tract

• reproductive organs

sympathetic

• thoracolumbar outflow via

• spinal nerves T1 to L4

• via sympathetic chain

• to head and neck T1-T3

• to organs of thorax abdomen and pelvis

• disributed via several peripheral ganglia

autonomic vs somatic motor neurons

autonomic

• pre and post ganglionic

• myelinated presynaptic and unmyelinatd post synaptic

• can be ach or nad

somatic

• one neuron only

• always excitatory

vagosympathetic tract what does it contain

parasympathetic traveling caudal direction and

sympathetic traveling cranial in neck

clinical significance of the vagosympathetic trunk

runs within the carotid sheath deep to to the jugular groove

vulnerable to needle stick injuries

control centres of autonomic

brainstem and hypothalamus