21. Autonomics Flashcards
Where do visceral sensory and motor innervations go to?
Generally to structures in body cavities (but not always)
Visceral sensory
Stimuli associated with blood vessels and internal organs
Visceral motor (autonomic nervous system) characteristics
Unlike somatic motor, can excite or inhibit the target
Regulates below conscious level (deep to cortex): heart function, blood pressure, body temp, respiration, sweating, digestion, etc
Visceral motor controls
Cardiac muscle (myocardium of heart)
Smooth muscle (digestive tract, bronchi, blood vessels, eye muscles)
Glands (salivary, digestive, lacrimal, sweat, sex glands)
Similarities between somatic and visceral sensory neurons
Very similar
Both have single neuron pathway in PNS
Both have cell bodies in dorsal root ganglia and synapse in dorsal horn
Somatic sensory indicates
Skin/body wall
Temp, pain, pressure, touch, proprioception
Easy to pinpoint
Visceral sensory indicates
Organs in body cavity
Temp, pain, stretch (hunger, nausea, fullness, etc)
Unlocalized
Somatic motor controls
Skeletal muscle
1 neuron pathway
Visceral motor controls
Smooth, cardiac muscle, glands
2 neuron pathway- presynaptic neuron (preganglionic) and postsynaptic neuron (postganglionic)
Sympathetic division used for
Greater physiological demand (exercise, fight or flight response)
Parasympathetic division used for
Routine function
Maintain homeostasis
“Rest and digest”
Where do sympathetic and parasympathetic neurons innervate?
Almost all of the same targets, but with opposite effects
Components of autonomic nervous system
Craniosacral division and thoracolumbar division
Craniosacral division neurons and neurotransmitters
Long pregangionic, short postganglionic neurons
Neurotransmitter: acetylcholine
Thoracolumbar division neurons and neurotransmitters
Short pregangionic, long postganglionic neurons
Neurotransmitters: preganglipmic is acetylcholine and postganglionic is norepinephrine
What cranial nerves have parasympathetic function
Oculomotor nerve (CN III)
Facial nerve (CN VII)
Glossopharyngeal nerve (CN IX)
Vagus nerve (CN X)
Parasympathetics of oculomotor nerve (CN III)
Targets:
Pupil (constricts via sphincter pupillae muscle)
Lens (thickens via ciliary muscle)
Parasympathetics of facial nerve (CN VII)
Targets:
Lacrimal gland to produce tears
Submandibular and sublingual salivary glands to produce saliva
Parasympathetics of glossopharyngeal nerve (CN IX)
Targets parotid salivary gland to produce saliva
Parasympathetics of vagus nerve (CN X)
Targets
Lungs (constrict bronchioles)
Heart (decrease heart rate)
GI tract (increase activity of digestive system)
Parasympathetics of S2-S4
Targets pelvic organs and external genitalia
Sympathetic target
Pupil (dilate)
Lens (thin)
Lacrimal gland (decrease tear production)
Salivary glands (decrease saliva production)
Lungs (dilate bronchioles)
Heart (increase heart rate)
GI tract (decrease activity of digestive system)
Sweat glands (produce sweat)
Characteristics of the sympathetic trunk (chain)
Nerve “chain” with ganglia
Pre- and post-ganglionic sympathetic neurons synapse in ganglia
Allows for sympathetic neurons to travel up and down beyond thoracolumbar region
Where are pre- and post- ganglionic sympathetic neurons’ cell bodies
Pre-ganglionic cell bodies in lateral horn of spinal cord between T1-L2
Ganglia in sympathetic trunk contain cell bodies of post-ganglionic neurons
Sympathetic trunk connects …
To spinal nerves via short branches
Targets of Sympathetics to body wall
Targets: sweat glands, blood vessels, and Arrector pili muscles (these targets do not have Parasympathetic innervation)
Pathway of sympathetic to body wall
Pathway 1:
Preganglionic neuron enters sympathetic trunk
Synapses with postganglionic neuron in chain ganglion
Postganglionic neuron rejoins spinal nerve to body wall target
Target of sympathetics to body cavity
Visceral organs (heart, digestive tract, kidneys, uterus)
Pathway of sympathetics to body cavity
Pathway 2:
Preganglionic neuron enters sympathetic trunk
Joins splanchnic nerve
Synapses with postganglionic neuron at collateral ganglion
Postganglionic neuron travels to target
What is fight or flight response
Sympathetic division responding to emergency situation
Pathway of fight or flight response
Pathway 3:
Preganglionic neuron enters sympathetic trunk and pass through without synapsing
Preganglionic neuron travels directly to adrenal gland to synapse with cells in the medulla
Cells in adrenal medulla release epinephrine (Adrenalin) and norepinephrine directly into blood stream for rapid, systemic effect
