intro to ANS

Question 1

Two important properties of the ANS

Answer 1

The efferent activity of the ANS is a True autonomic control because we are not aware of such control, the efferent ANS output goes to viscera and has two synergistic components: the sympathetic NS and the parasympathetic NS which acts like a brake to attenuate such activity

Question 2

Organization of the ANS

Answer 2

Three divisions: Sympathetic, parasympathetic and the Enteric NS

The efferents of the Sympathetic and parasympathetic consists of two neuron relay system (pre ganglionic and a post ganglionic)

Cell bodies of the preganglionic: SNS (thoracolumbar), PNS (craniosacral)

Question 3

Neuroanatomical design of the ANS sympathetic division

Answer 3

Sympathetic paravertebral ganglia: forms the sympatheitc chain, hold the axons of preganglionic), sympathetic prevertebral ganglion (located in the abdoment and pelvic region adjacent to the major blood vessels, hold the cell bodies of the post ganglionic)

Sympathetic preganglionic fibers (have cell bodies in the lateral horns T1-L3) receive input from CNS or the sensory neurons, axon exits thru the ventral root enter synaptic chain via white rami, then in sympathetic chain they synapse with post in the prevertebral ganglion (exit via gray)

Sympathetic post ganglions( cell bodies mostly in the pre vertebral ganglion, but some in the para then to organs)

Afferents sensory (one neuron system with long dendrite) cell bodies in the DRG (dorsal root ganglion) axons and form dorsal roots (in the ganglion they branch into afferent and efferent: afferents branch convey viceral and somatic sensory, efferent goes to the brain and CNS)

Question 4

Neuroanatomical design of the ANS parasympathetic division

Answer 4

Preganglionic parasympathetic cell bodies in the Craniosacral region( branstem)

Preganglionic axons travel through the the ventral roots, postganglionic axons are very short

Question 5

Somatic and autonomin ns efferent pathways, NTs and receptors

Answer 5

Somatic: one long Axon from the CNS to the nicotinic receptor on muscle cell and activated by Ach

Parasympatheic NS: one super long preganglionic (from craniosacral) synapses with a short post ganglion and activates muscarinic receptors (via Ach)

Sympathetic NS: one short preganglionic (from thoracolumbar) synapses with a kinda long post ganglionic (cell bodies in Pre gang and Para) and release epi or nor epi on adrenergic receptorts
in adrenal medulla (Ach activates nicotinic receptors on chromaffin cells that release Epi in the blood)