Flashcards in Autonomic Nervous System Deck (46):
Define the autonomic nervous system?
Involuntary nervous system
Visceral motor system
What is the purpose of the ANS?
What sorts of actions can the ANS have?
Part of simple reflexes
Involve coordinated regulation of multiple sites
Associated with more complex behaviour
What are the features of the ANS?
What are the targets of autonomic nerves?
Smooth and cardiac muscle
Epithelial transport of ions
Hormones and mucous secretions
What are the components of the ANS?
Where are the parts of the sympathetic and parasympathetic nervous systems?
Do the sympathetic and parasympathetic nervous systems require the CNS for function?
Where is the enteric nervous system?
Does the enteric nervous system need the CNS to function?
No, can function independently
What neurons make up the enteric nervous system?
Do the sympathetic and parasympathetic nervous systems influence the enteric nervous system?
How are the sympathetic and parasympathetic nervous systems defined?
By their anatomy - location of their preganglionic neurons
Where are the sympathetic preganglionic neurons?
In thoraco-lumbar region of spinal cord
Where are the parasympathetic preganglionic neurons?
In cranio-sacral region of spinal cord
Which areas of the spinal cord have no visceral fibres?
Cervical and lumbar enlargements
What nucleus in the spinal cord are sympathetic preganglionic cell bodies located?
What are the two types of sympathetic ganglia?
Paravertebral = sympathetic chain
Prevertebral = mesenteric ganglia
Other than the sympathetic ganglia, what else do preganglionic sympathetic neurons innervate?
What is the sympathoadrenal system?
Preganglionic sympathetic neurons and adrenal medulla
Where are the preganglionic parasympathetic cell bodies located?
Sacral spinal cord
What are the preganglionic parasympathetic nuclei of the brainstem?
Dorsal motor nucleus of vagus and nucleus ambiguus
Where do neurons project to from the Edinger-Westphal nucleus, and what do they control?
To ciliary ganglion to control sphincter pupillae and ciliary muscle
Where do neurons project to from salivatory nuclei, and what do they control?
To submandibular, sphenopalatine, and otic ganglia to control lacrimal, salivary, sublingual, nasal, and palatine glands
Where do neurons project to from the dorsal motor nucleus of vagus and nucleus ambiguus, and what do they control?
To microganglia near and on outer surface of thoracic and abdominal organs, controlling many functions
Where in the sacral spinal cord is the parasympathetic preganglionic nucleus?
Where are sacral postganglionic parasympathetic neurons?
In pelvic/inferior hypogastric plexus
Are the pelvic ganglia purely parasympathetic?
No, they contain many sympathetic neurons > mixed ganglia
What is the clinical significance of the long axons of the pelvic plexus?
Vulnerable to surgical injury
Are ANS neurons myelinated or unmyelinated?
Where are neurotransmitters stored in postganglionic fibres?
In swellings along axon = varicosities
Can be released from any of them
What is the significance of transmitter release from varicosities?
Transmitter released over large area so it has large effect in coordinated way
What is the preganglionic transmitter, and what receptor does it act on?
What is the postganglionic sympathetic neurotransmitter and what receptor does it act on?
What is the postganglionic parasympathetic neurotransmitter, and what receptor does it act on
How many subtypes of ACh and NA receptors are there?
Are ACh and NA the only transmitters used by the ANS?
No, many others used
How does the ANS gather information?
Caudal part of nucleus of thee solitary tract (NTS) in medulla receives sensory input
What is the major integrative centre of autonomic function?
Where is sensory information distributed to?
Provide feedback to reflexes > control organ/tissue function
Provide info to higher centres to drive more complex responses
What is the role of the hypothalamus in the ANS?
- Sensory inputs
- Contextual info from other brain regions
- Hormonal signals
Compares situation to biological set points > adjusts behaviour, autonomic and endocrine function
What does the fight or flight response involve?
Mass activation of many sympathetic pathways at once to overcome/escape from major threat
Why doe mass activation and synchronisation occur in the fight or flight response?
CNS activates many preganglionic pathways at once
Some preganglionic neurons have many axon collaterals > activate many postganglionic neurons at once
When adrenal medulla activated catecholamine hormones spread through bloodstream
When is mass activation of the sympathetic nervous system relevant?
How does the sympathetic nervous system mediate functions essential for normal living?
Individual cells/tissues/organs precisely and independently activated
Adrenal medulla nerves not always activated