Autonomic Nervous System Flashcards
What is the job of the autonomic nervous system?
Regulate the activities of cardiac muscle, smooth muscle, and glands.
Structurally, what two main components does the ANS consist of?
- visceral afferent sensory neurons
- visceral efferent motor neurons (2)
* somatic nervous system has 1 motor neuron
Functionally, the ANS operates?
- without conscious control
- reflex arc dependent
- with medullary and hypothalamic override
What are the two divisions of the ANS?
Sympathetic and Parasympathetic
Compare the receptors for the somatic and autonomic nervous systems?
Somatic
- cutaneous receptors
- proprioceptors
- special senses
Autonomic
- chemoreceptors
- baroreceptors
- mechanoreceptors (stretch)
Does the autonomic and/or somatic nervous systems require consciousness?
Autonomic - unconscious
Somatic - may become conscious
What effect on the effectors do the somatic and autonomic nervous systems have?
Somatic
-excitatory for skeletal muscles
Autonomic
-excitatory or inhibitory for cardiac, smooth muscle and glands
How many motor neurons leave the CNS for the somatic and autonomic nervous systems?
Somatic - single neuron
Autonomic - two motor neurons
Explain the differences between somatic and autonomic nervous systems in the picture
What is the general autonomic nervous system pathway?
- Preganglionic Neuron
- Ganglion
- Postganlionic neuron
What is the preganglionic neuron in the autonomic nervous system pathway?
Originates in the CNS
- first of the two autonomic motor neurons
- cell body located in gray matter of spinal cord or brain
- preganglionic axon passes from CNS in a spinal or cranial nerve
- axon terminates in a ganglion
What is the ganglionin the autonomic nervous system pathway?
- collection of nerve cell bodies located outside the CNS
- cell bodies give rise to postganglionic neurons
What is the postganglionic neuron in the autonomic pathway?
- second of the two autonomic motor neurons
- cell body located in a ganglion
- postganglionic axon passes from ganglion to the effector
- peripheral effector is either stimulated or inhibited
Where are the cell bodies located in the sympathetic nervous system?
T1-L2 vertebra = Thoracolumbar outflow
- sympathetic nervous system cell bodies are in the lateral gray horns of these vertebra
Where are the ganglia located in the sympathetic nervous system?
In the sympathetic chain
or
There are 3 prevertebral ganglion
- Celiac Ganglion
- Superior mesnteric ganglion
- Inferior mesenteric ganglion
How is the sympathetic nervous system related to the adrenal medulla?
The adrenal medull ais a collection f post-ganglionic neurons from the sympathetic nervous system
-causes epinephrine or norepinephrine to go into circulation
Walk through sympathetic nervous system pictured.
- Thoracolumbar outflow T1-L2
- Sympathetic chain
- Prevertebral
- Adrenal medulla
Where do the parasympathetic nervous system cell bodies originate?
Craniosacral outflow
Lateral Gray horns S2-S4
Cranial Gray matter CN III, VII, IX X
What are intramural ganglia in the parasympathetic nervous system?
Terminal Ganglia - the ganglia ends right at organ
- Preganglionic neuron = very long
- Postganglionic neuron = very short
What are the physiological effects of the ANS?
Dual innervation of effectors
- innervated by symp/parasymp NS for antagonistic or cooperative efects
Different postganglionic neurotransmitters
- acetylcholine or norepinephrine
Parasympathetic tone
- balance between symp and parasymp regulated by hypothalamus
- Normally parasymp is turned up and symp is down
What are the autonomic neurotransmitters and how are degraded?
Cholinergic
- acetylcholine
- degraded by acetylcholinesterase
Adrenergic
- norepinephrine
- degraded by catechol-O-methyltransferase or monoamine oxidase
- slow process so norepinephrine tends to diffuse thru body
What kinds of neurons use cholinergic and adrenergic neurotransmitters?
Cholinergic
- all pregang. neurons in symp/parasymp NS
- all postgang. parasym. neurons
- a few postgang. symp. neurons
Adrenergic
- most postgang. symp. neurons
What are the activities of the parasympathetic nervous system?
- energy conservation-restoration system
- SLUD (salivation, lacrimation, urination, defecation)
- eye function (constricting pupil, accommodation reflex)
- dominates sympathetic nervous system most of the time
- effects short-term and very localized
- (acetylcholinesterase works fast)
What are the activities of the sympathetic nervous system?
- energy expenditure system
- dominates parasympathetic nervous system when activated
- effects long-lasting and widespread
- broken down slowly = diffusion into blood
- divergence = 1 preganglionic stimulates up to 500 postganglionics
- Physiological changes
- increased heart rate + force of contraction + vasoconstriction = increased blood pressure
- increased respiratory rate + bronchodilation = increased blood oxygen
