Chapter 15 - Autonomic Nervous System

what are the parts of the SNS?

somatic sensory and somatic motor

what do somatic sensory do?

detect stimuli from special senses, skin, and proprioreceptros, they send info to the CNS

what is the somatic motor portion and what does it do?

it transmits nerve signals from the CNS to control skeletal muscles

what are the parts of the ANS?

visceral sensory and autonomic motor

what does the visceral sensory do?

detect stimuli from internal organs and send information to the CNS

what does the autonomic motor do?

it transmits nerve signals from the CNS to smooth muscles, cardiac muscles, and glands.

describe the lower motor neurons of the SNS

Lower motor neurons in the somatic nervous system directly innervate skeletal muscles, facilitating voluntary muscle movements.

The features are

myelinated

large diameter/fast conduction

They always release ACh from synaptic knob

describe the lower motor neurons of the ANS

Lower motor neurons in the autonomic nervous system control involuntary functions by innervating smooth muscles, cardiac muscles, and glands. They may release either acetylcholine or norepinephrine at their synapses, depending on the target organ and the type of response needed.

They are a chain of two motor neurons.

first neuron: preganglionic neuron located in the CNS/brainstem/spinal cord, which is myelinated and transmits signals to the second neuron in the ganglion.

They have a smaller diameter than the SNS, which means a slower conduction

Release ACh

secondary neuron: postganglionic neuron located in the ganglion, which is unmyelinated and transmits signals to the target organ.

they have the slowest conduction.

they release ACh OR norepinephrine/NE from knobs

Have neuronal convergence or divergence

what is neuronal convergence

multiple preganglionic neurons synapsing with a single cell

what is neuronal divergence

axons from one preganglionic cell synapsing with numerous cells

what are the two divisions of the ANS

parasympathetic (rest & digest) and sympathetic (fight or flight)

what are the features of the parasympathetic

also known as craniosacral. (s2-s4)

preganglionic neuron are located in brainstem or S2-S4 spinal cord

ganglionic neurons innervate muscles or glands

PREGANGLIONIC AXONS LONGER THAN POST; few preganglionic neurons

what are the features of the sympathetic

preganglionic neurons located in lateral horns

also known as thoracolumbar

ganglionic neuron innervate muscles or glands

PREGANGLIONIC AXONS SHORTER THAN POST; many preganglionic axons

what are the ans neurotransmitters

ACh and NE

what is acetylcholine released and synthesized from and what are the two types of receptors for ACh

cholinergic neurons, nicotinic and muscarinic

what is norepinephrine released and synthesized from

adrenergic neurons