Autonomic Nervous System Flashcards
What makes up the central nervous system? What does it do?
the brain and spinal cord with affiliated nuclei (gray matter) and tracts (white matter) that relays and integrates information recieved from the periphery of the body
What makes up the peripheral nervous system? What does it do?
comprised of nerves and ganglia that are responsible for the transmission of sensory input and motor output to/from the CNS from/to the periphery of the body
What is nervous tissue comprised of?
neurons and supporting cells
What do neurons represent in the nervous system?
the electrical conducting cells
What is the receiving end of the neuron? What does it do?
dendrites - relays information toward the cell body
What is the conducting portion of the neuron? What does it do?
axon - relays information away from the cell body
What is the classification of neurons based on their structure determined by?
the number of processes that emanate from the cell body
What are the 4 classifications of neurons? (based on structure)
- Anaxonic
- Bipolar
- Unipolar
- Multipolar
What are the 2 classifications of neurons? (based on function)
- Afferent
- Efferent
What do afferent neurons do?
relay sensory information input to the CNS. conduct impulses from peripheral sensory receptors and into the CNS
What are the two most common afferent neuron structures? What do they do?
Bipolar - linked with special sensory systems, such as olfaction, vision, taste
Unipolar - transmit general sensory information from the periphery of the body and into the CNS
What do efferent neurons do? What is their structure?
relay motor output (via impulses)from the CNS to peripheral tissues - structurally they are multipolar
Where are the cell bodies of afferent neurons located?
outside the CNS (within the PNS)
- cell bodies of afferent neurons below the head region are located within bilateral dorsal root ganglia
Where are bilateral dorsal root ganglia located?
on either side of the spinal cord at each spinal segment
How do axons of several efferent neurons travel?
collectively together outside of the CNS within nerves
Where are efferent neuron cell bodies located?
within the CNS within nuclei that make up the gray matter of the CNS
What are two types of efferent neurons?
somatic and visceral
What is another name for autonomic neurons?
visceral efferent neurons
What are the characteristics of interneurons?
- the entire neuron is located within the CNS
- cell bodies are within nuclei of CNS gray matter
- axons travel collectively within tracts, which comprise the majority of the CNS white matter
What are the three different tracts with regards to interneurons and the CNS? Where are they?
- Ascending tracts - extend from spinal cord to brain
- Descending tracts - extend from brain to spinal cord
- Association tracts - extend between brain nuclei
What do interneurons do?
provide integration of information between the PNS and CNS.
- relay information to other interneurons
- relay input to the brain from the spinal cord
- transmit motor output from the brain back to the spinal cord
What are spinal reflexes? (interneurons)
integration between afferent and efferent neurons within the spinal cord
What is primarily mediated by the peripheral nervous system?
Sensory input and motor output
What is a principle role of the central nervous system?
integration
Unconscious integration occurs at what level?
at the level of the spinal cord
Conscious integration occurs at what level?
at the brain
Where is the dendritic zone located and what does it receive?
located outside of the CNS and receives sensory innervation from the tissues of the body
What is afferent information transmitted towards and where is it located?
towards the sensory neuron cell body which is located within a dorsal root ganglion of the PNS
True or false? Axons of afferent neurons extend through the dorsal root and transmit sensory information into the spinal cord gray matter where they synapse onto interneurons.
True
What are two types of efferent neurons?
somatic and visceral
What do axons of somatic efferent neurons do?
extend all the way to their target tissue and do NOT synapse before reaching their target tissue
What are voluntary tissues?
skeletal muscle
What do the axons of visceral efferent neurons do?
synapse onto a second neuron and it is the second neuron that directly innervates the target tissue
What are involuntary tissues?
smooth muscle, cardiac muscle, and glands
What is a nerve?
neuron processes of several neurons traveling collectively together within the PNS (outside brain/spinal cord)
What is a ganglion?
collection of neuron cell bodies located within the PNS (outside brain/spinal cord)
Where are the cell bodies of efferent neurons always located? What do they form?
always located in the CNS and form aggregations with other efferent neuron cell bodies within the CNS
What are aggregations of neuron cell bodies within the CNS called?
Nucleus (single) or nuclei (plural)
What is gray matter?
aggregations of nuclei within the CNS
- the axonal processes extending from these neurons are collectively within nerves, where they may be coupled with processes of afferent neurons
What is a mixed nerve?
a nerve comprised of both sensory neuron fibers and motor neuron axons
What does the somatic motor division of the PNS supply?
voluntary tissues (skeletal m.)
What does the autonomic (visceral) motor division of the PNS supply?
involuntary (smooth m., cardiac m., and glands)
What are the characteristics of a pre-synaptic/ganglionic neuron?
- cell body is located in the CNS (brain nucleus/spinal cord gray matter)
- Axon synapases onto second autonomic neuron
What are the characteristics of a post-synaptic/ganglionic neuron?
- cell body is located within an autonomic ganglion
- recall that ganglia are located outside of the CNS!
- axon synapses with target tissues.
What are spinal nerves?
Originate in the spinal cord and are mixed nerves comprised of sensory and motor neuron fibers which separate near their continuation into/out of the spinal cord
What extends into the dorsal root of the spinal nerve?
afferent (sensory) axons of both somatic and visceral sensory neurons
What does the visceral root of spinal nerves contain?
- contains somatic motor neuron axons that extend from motor neuron cell bodies located within the ventral horn of the spinal cord gray matter
- may also contain visceral motor (autonomic) neuron axons that extend from motor neuron cell bodies located within the lateral horn of the spinal gray matter
Where do cranial nerves originate from? What do they innervate?
brain nuclei and innervate structures of the head and neck
How many cranial nerves are there?
12
True or false? All cranial nerves are mixed nerves.
False, not all of them are.
What cranial nerves contain autonomic neurons?
- Oculomotor (CN III)
- Facial (CN VII)
- Glossopharyngeal (CN IX)
- Vagus (CN X)
What are the two branches of the autonomic nervous system?
sympathetic and parasympathetic
What is another name for the sympathetic division of the autonomic nervous system? Why is it called this?
thoracolumnar division because pre-synaptic fibers exit the spinal cord from the first thoracic (T1) to the second lumbar (L2) levels
Where do pre-synaptic neurons generally synapse? (sympathetic) why?
Pre-synaptic neurons fibers are short and generally synapse within the sympathetic chain of ganglia (paravertebral) which is located on either side of the spinal cord
What is another name for the parasympathetic division? Why is it called this?
craniosacral division because pre-synaptic fibers originate in the brain and also in the sacral levels of the spinal column
Where do pre-synaptic neurons generally synapse? (parasympathetic) why?
pre-synaptic neuron fibers are long and generally synapse in ganglia that are located within the organs that they innervate
What do all pre-synaptic sympathetic (pre-SNS) axons enter?
a chain of ganglia adjacent to the vertebral bodies
What are the names of the chain of ganglia adjacent to the vertebral bodies?
- sympathetic trunk
- sympathetic chain
- Paravertebral chain
What are paravertebral ganglia comprised of?
post-SNS cell bodies located on either side of the vertebral column
True or false? The axons of pre-SNS neurons may synapse on the post-SNS cell bodies located within the ganglia of the chain.
True
True or false? Pre-SNS neurons can NOT synapse within pre-vertebral ganglia.
false. Some can
Where are pre-vertebral ganglia located? What are they comprised of?
caudal to the diaphragm adjacent to major arterial branches of the abdominal aorta. comprised of post-SNS cell bodies
What do splanchnic nerves do and what are they comprised of?
communicate with pre-vertebral ganglia. Comprised of pire-synaptic SNS axons that do not synapse within the paravertebral chain
What is the celiac ganglion located near?
the origin of the celiac artery
What is the cranial mesenteric ganglion located near?
the origin of the cranial mesenteric artery
What is the caudal mesenteric ganglion located near?
the caudal mesenteri artery
What is the name given to the cranial mesenteric and celiac ganglion because they are so close together/affiliated?
celiacomesenteric ganglion and plexus
What are the names of cervically located ganglion upon which pre-SNS neurons synapse onto when they extend cranially to supply structures within the thorax and head region?
- cervicothoracic ganglion
- Middle cervical ganglion
- Cranial cervical ganglion
Where are pre-synaptic cell bodies of PSNS neurons located?
within brain nuclei and the sacral regions of the spinal cord
True or false? PSNS and SNS neurons are distributed in the same way despite their different origins
True
What does the vagus nerve do?
carries pre-PSNS axons from the brain to the thorax and abdomen
Where are the majority of post-PSNS cell bodies located? What are they named?
within ganglia within the walls of the organs that they innervate.
- Referred to as terminal ganglia
True or false? Neither branches of the ANS have origins from the cervical region of the spinal cord and do not supply components within the cervical visceral space.
False. Neither branches of the ANS have origins from the cervical region of the spinal cord, but the vagosympathetic nerve trunk transmits ANS components within the cervical visceral space
