Autonomic nervous system Flashcards
What is the purpose of the autonomic nervous system?
Maintaining homeostasis and survival
Which tissue types does the CNS innervate?
Everything except the CNS tissue and skeletal muscle
What are the three divisions of the ANS?
Sympathetic NS
Parasympathetic NS
Enteric NS
Describe the general pattern of innervation of the sympathetic and parasympathetic NS?
Most organs are innervated by both sympathetic and parasympathetic nerves, but each system usually innervates different tissues.
Which spinal cord segments are the sympathetic and parasympathetic nerves derived from?
Sympathetic: thoraco-lumbar
Parasympathetic: cranio-sacral
Where in the spinal cord do autonomic pathways NOT originate from?
Cervical or lumbar enlargements
Why don’t autonomic pathways originate from cervical or lumbar enlargements?
Upper and lower limb nerves originate from here
Describe the location of sympathetic and parasympathetic ganglia?
Sympathetic ganglia are more distant from organs
Parasympathetic ganglia are closer to or within organs
What are the two divisions of sympathetic ganglia?
Prevertebral ganglia
Paravertebral ganglia
Describe the general organisation of sympathetic and parasympathetic nerves (in terms of strucutre, ganglia, etc.)?
Sympathetic: short preganglionic, long postganglionic fibres
Parasympathetic: long preganglionic, short postganglionic fibres
Preganglioinc fibres are lightly myelinated or unmyelinated, whereas all postganglionic fibres are unmyelinated
Which NTs are used by sympathetic and parasympathetic nerves?
What are non-classical transmitters?
Give some examples?
NTs that are not Ach or NA
aka ‘non-adrenergic, non-cholinergic’
eg. NO, ATP, NPY
What is co-transmission?
More than one NT can be released at one time
How does the ANS differ from the CNS in terms of the primary transmitters?
ANS: Ach and NA
CNS: glutamate and GABA
Describe the junctions of ANS nerves and their target organs?
No easily visible junction
More than one transmitter release site per axon
Extra-junctional receptors present