damage to the ANS increases the effector response to stimulation Ganglia
a cluster of nerve cell bodies that lie outside the CNS
Divergence-Preganglionic fibers branch to synapse with numerous postganglionic fibers (up, down, level) Convergence-Postganglionic fibers receive input from numerous preganglionic fibers Sympathetic system is activated as a unit
the closely related functioning adrenal medulla and sympathetic nervous system. Promotes fight or flight response Dual Innervation
Antagonistic- SNS and PSNS exert opposite effects
-Heart Rate: SNS increases PSNS decreases
Complementary-SNS and PSNS exert similar effects
-Salivary glands: PSNS alone produces watery saliva, SNS and PSNS produce thicker saliva Cooperative-SNS and PSNS act differently but work together
-Micturition:SNS increases tone of bladder muscles, PSNS promotes contraction -Penis:PSNS causes erection,ejaculation is due to SNS
What are the two divisions of the ANS?
Sympathetic-fight or flight
Parasympathetic-rest and digest
Sympathetic Nervous System
"Thoracolumbar" -SNS ganglia are found primarily along vertebral column Preganglionic Neurons: Thoracic and Lumbar levels of spinal cord (T1-L2) Ganglia: Paravertebral, collateral a.k.a. Prevertebral
Function: Fight or Flight
Parasympathetic Nervous System
"Craniosacral"- most parasympathetic pathways originate in brain stem and sacral region. Preganglionic Neurons: Brain(midbrain, medulla,and pons) and sacral levels (S2-S4) of spinal cord Ganglia-Terminal Ganglia
Function: read, relax, and rejuvenate (except when you dont) What type of neurons are in the ANS?
Preganglionic Neuron-originates in the CNS, B Fibers, small myelinated Postganglionic Neuron- C fibers, smaller, unmyelinatd
Why is the white ramus white?
Because it is mostly made up of Preganglionic neurons, which are myelinated giving it its white apperance. These are faster in conducting nerve impulses Why is the gray ramus gray?
because it is made up of postganglionic neurons which are unmyelinated, which lead to a slower conduction rate Paravertebral Ganglia
most sympathetic ganglia are located paravertebral or close to the spinal cord Prevertebral Ganglia
Collateral ganglia, lie anterior to the vertebral column
ganglia in the walls of the organs where the nerves terminate PSNS
Which division has long preganglionic fibers?
Which division has long postganglionic fibers?
Why is the adrenal medulla included in the sympathetic nervous system? Medullary cells are modified neurons
Secrete norepinephrine, and epinephrine
Preganglionic neurons project from spinal cord to adrenal medulla, where they synapse. Release epinephrine-fight or flight response
Which three cutaneous effectors only receive innervation from the SNS? blood vessels, arrector pili muscles, sweat glands.
What receptors are used by the SNS?
Alpha and Beta adrenergic receptors
What receptors are used by the PSNS?
Nicotinic and muscarinic cholinergic
What cranial nerves carry parasympathetic fibers?
What cranial nerve is the most important for homeostasis?
What is an "en passant" synapse?
No axon terminals
Varicosities allow for the whole axon to be utilized
Appear part way along axon
Neural synapses happen at the end of the axon
How does the SNS control homeostasis in the organs in innervates alone? frequency of SNS firing
Arrector Pili Muscles
Most blood vessels
-constriction by SNS acting on alpha adrenergic receptors;vasodilation results from decreased SNS stimulation ACh Nicotinic
Cholinergic Acetycholine Nicotinic Excitatory
BUD SAW a Musc:
Bradycardia,Urination,Digestion, Sweating,Arousal, Wheezing,Acetycholine, Muscarinic Adrenergic Alpha 1
Urinary sphincter contracts, ...
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