4. Autonomic Nervous System Flashcards
Compare control of SNS and ANS
SNS: voluntary
ANS: involuntary
Compare number of neurons in pathway of SNS and ANS
SNS: single motorneuron
ANS: a preganglionic and postganglionic neuron
Compare cell body location of SNS and ANS
SNS: CNS
ANS: CNS for preganglionic and autonomic ganglion for post ganglionic
Compare effectors of SNS and ANS
SNS: skeletal muscle
ANS: cardiac muscle, smooth muscle, glands
Compare NTs and receptors of SNS and ANS
SNS: ACh/AChR
ANS: Preganglionic neuron: ACh/nAChR; postganglionic neuron: ACh/mAChR and NE/a1, a1, b1, b2
Divisions of autonomic nervous system
Sympathetic: ‘fight or flight’ (e.g. the body responds to fear, a difficult exam, a burning house, or an attacker)
Parasympathetic: ‘rest-and-digest’ (e.g. sexal arousal, salivation, lacrimation, urination, digestion, and defecation)
Describe the two neurons in series that connect the spinal cord and effector organs of the sympathetic division
Cell bodies of preganglionic sympathetic neurons are in thoracic and lumbar regions of spinal cord (T1-L3)
Thoracolumbar
Cell bodies of postganglionic sympathetic neurons are in:
-Paravertebral ganglia (sympathetic chain)
-Prevertebral/collateral ganglia (celiac, superior and inferior mesenteric ganglia)
Length of axons: short pre-ganglionic and long post-ganglionic
Adrenal gland
A speicalized sympathetic ganglion
Cell bodies of preganglionic located in thoracic spinal cord (T5-T9)
The axon of preganglionic neurons pass through the sympathetic chain and the celiac ganglion without synapsing, and travel to adrenal medulla, where they synapse on chromaffin cells
Endogenous analgesia system
Includes the secretion by the brain of endorphins in response to the central perception of pain.
Opioids and serotonin/catecholamines come from adrenal gland
Describe two neurons in series that connect the spinal cord and effector organ in the parasympathetic division
Cell bodies of preganglionic parasympathetic neurons are in nuclei of cranial nerves (III, VII, IX, X) and sacral region of spinal cord (S2-S4).
Craniosacral
Cell bodies of postganglionic parasympathetic neurons are within or very close to effector organs.
Length of axons: long pre-ganglionic axon; short post-ganglionic axon.
Sympathetic vs parasympathetic: origin of preganglionic nerve
Sympathetic=thoracolumbar
Parasymapthetic=craniosacral
Sympathetic vs parasympathetic: location of ganglia
Sympathetic=far from effector organs
Parasymapthetic=near or within effector organs
Sympathetic vs parasympathetic: length of preganglionic nerve
Sympathetic=short
Parasymapthetic=long
Sympathetic vs parasympathetic: length of post ganglionic nerve
Sympathetic=long
Parasymapthetic=short
Neuromuscular junction
The junction between motoneuron and its effectors (skeletal muscle fibers)
Motor end plate
Nerve terminals
Neuroeffector function
The junction between postganglionic autonomic neurons and its effectors (target tissues)
Branching networks
Varicosities
Neuroeffector junction vs. Neuromuscular junction: arrangement
neuroeffector junction = diffuse, branching networks
neuromuscular junction= discrete, organized structure called motor end plate
Neuroeffector junction vs. Neuromuscular junction: innervation
neuroeffector junction = target tissues may be innervated by many postganglionic neurons
neuromuscular junction= a skeletal muscle fiber is innervated by a single motorneuron
Neuroeffector junction vs. Neuromuscular junction: NT storage sites
neuroeffector junction = varicosities
neuromuscular junction= nerve terminals
Neuroeffector junction vs. Neuromuscular junction: postsynaptic receptors
neuroeffector junction = postsynaptic receptors are widely distributed on the target tissue
neuromuscular junction= postsynaptic receptors are located in the specialized motor end plate
Adrenergic neurons
Synthesize and release norepinephrine
Adrenoreceptors
a1, a2, b1, b2; activated by NE or epinephrine
Cholinergic neurons
neurons that synthesize and release ACh
Cholinoreceptors
Nicotinic AChR, muscarinic AChR; activated by ACh
Similarities of ACh in both ANS divisions
Preganglionic neurons release ACh that activates nAChR on postganglonic neurons in both sympathetic and parasympathetic divisions.
A substantial amount of nicotine (nAChR agonist) will cause…
Increase parasympathetic AND sympathetic response.
Non-classic neurotransmitters in parasympathetic division
VIP (vasoactive intestinal peptide)
NO (nitric oxide)