Nervous System Flashcards
What is the Nervous System made up of?
Neurons + glial cells
1) What is the neuron?
2) What are the glial cells and what are they involved in?
1) functional cell of NS
2) supporting cells - they wrap axons in myelin
What 3 actions is the neuron involved in?
1) receives excitation (at a synapse or receptor) or becomes excited
2) conducts excitation along an axxon
3) transmits excitation (via release of chemical at synapse)
What is a multipolar neuron?
the cell body is located where input excitation occurs (in center of receptor region)
What is a unipolar neuron?
the cell body is located along the axon (in a spinal ganglion)
Are most neurons multipolar or unipolar?
multipolar
- Label which neuron is mutlipolar and unipolar
- Label all the structures of each neuron.
Answers:
- Multipolar
- unipolar
- dendrites
- cell body
- axon
- synapse
- receptor
- axon
- cell body
- synapse
True or False:
Sensory neurons are multipolar.
False
Sensory neurons are unipolar
Excitable cell =
polarized plasma membrane
Define excitation
flow of ions across plasma membrane (membrane breaks down to allow ion flow)
What drives the flow of ions?
electrical gradient and ionic mileu
In unipolar neurons…
1) what does the receptor act as?
2) what triggers excitability
1) conducer
2) environmental energy
What are neurons dependent on?
local environment of ions
Define these terms:
1) nerve
2) root
3) ganglion
1) bundle of axons ensheathed by supporting cells adn enveloped by connective tissue
2) nerve that is adjacent to the CNS adn eveloped by meninges
3) localized site where a nerve is enlarged due to a collection of cell bodies
1) Name the two types of ganglia
2) Name which type of cell body each contain
1) spinal ganglia:
unipolar cell bodies
2) autonomic ganglia:
mutlipolar cell bodies
True of False:
Autonomic ganglia have synapses on them
True
they contain multipolar cell bodies which are located next to synapses
Where are spinal ganglia located?
on dorsal roots of cell bodies
What do autonomic ganglia innervate?
viscera
What are roots made up of and are they part of the PNS or CNS?
made up of rootlets and they are part of the PNS
Are unipolar neurons part of the CNS or PNS?
CNS
1) What are the two divisions of the NS?
2) Name the structures of each division
1) Central (CNS) and Peripheral (PNS)
2) CNS: brain and spinal cord
PNS: 12 pairs of cranial nerves (attached to brain)
36 pairs of spinal nerves (attached to spinal cord
8 cervial, 13 thoracic, 7 lumbar, 3 sacral, 5 caudal
What happens when info is urgent and needs to be transnmitted quickly?
the axons are wrapped in myelin
True or False:
Most axons are myelinated
False
Most axons are non-myelinated
Where is the spinal cord (CNS) and spinal roots (PNS) located?
within the vertebral canal of vertebral column
What is a spinal nerve made up of?
dorsal and ventral spinal roots united on each side
True or False:
dorsal rootlets contain unipolar neurons.
True
dorsal rootlets and ventral rootlets (which make up dorsal and ventral roots) unite to form spinal ganglion which is where the cell bodies are located within the unipolar neuron
1) where is the spinal nerve found?
2) What are the three layers of CT involved with eveloping spinal nerves?
1) in the intervertebral foramen (adjacent vertebrae combine to form this)
2) epineurium, perineurium and endoneurium
1) Where is each layer of CT located within the spinal nerve?
1) Endoneurium surrounds the whole nerve
2) Perineuron surrounds each fascicle within the nerve
3) Endoneurieum surrounds the axons within each fascicle
Describe some characteristics of spinal nerves
1) short
2) located at an intervertebral foramen
3) connected to the spinal cord by two roots
4) divides into 4 primary branches
What two roots connect the spinal nerve to the spinal cord and what are they composed of?
1) Dorsal root - composed of Afferent (sensory) axons
where spinal ganglion is located
2) composed of Efferent axons that innervate muscle and gland
Describe the 4 primary branches of the spinal nerve
1) Meningeal branch - small, sensory to meninges
2) ramus communicans - cnonects to sympathetic trunk and innervates viscera (ANS)
3) ventral branch - largest branch, innervates hypaxial muscles and muscles of limb and branches into lateral and ventral cutaneous nerves
4) dorsal branch - branches into medial and lateral branches; innervates epaxial muscles and further branches into dorsal cutaneous nerves
Label the numbered structures
1) Epineurium
2) Perineurium
3) Endoneurium
Label the numbered structures
- dorsal root
- spinal ganglion
- ventral root
- dorsal branch
- medial branch
- lateral branch
- ventral branch
- sympathetic trunk
- ramus communicans
- meningeal branch
Define fiber types
types of nerve fibers found in a spinal nerve and its branches
Name the two types of fiber and describe them
1) Afferent (sensory) - axons associated with receptors and unipolar cell bodies in spinal ganglia
2) Efferent (motor) - axons that innervate muscle and gland; cell bodies are located in the spinal cord
Name the two different divisions of afferent axons and where are they located?
1) General Somatic Afferent (GSA)
receptors in skin and muscles, tendons, joints
2) General Visceral Afferent (GVA)
receptors in viscera
Name the two divisions of efferent axons adn what they innervate
1) Somatic Efferent (SE)
innervates skeletal muscle
2) Visceral Efferent (VE)
innervates cardiac and smooth muscle and glands
What is unique about the VE pathway from the ANS?
it is composed of two multipolar neurons whereas the other pathways only have one.
1) where is the first neuron of VE located?
2) Where is the second neuron of VE located?
1) First neuron’s cell body is in the CNS (brain or spinal cord)
2) cell body of second nueron is located within autonomic ganglion in PNS
Name the 5 regions of cutaneous innervations and their branches
1) Neck - dorsal and ventral cutaneous
2) Thorax - dorsal, lateral and ventral cutaneous
3) Abdomen - dorsal and lateral cutaneous
4) Limbs - individually named cutaneous branches of regional nerves that originate from nerve plexuses (brachial or lumbosacral) to the limbs
5) Face - named cutaneous branches of cranial nerves
Where does Great Auricular nerve come from?
C-2 ventral branch
True or False:
C1 is not cutaneous
True
1) What does the brachial nerve plexus innervate?
2) What does the lumbosacral nerve plexus innervate?
1) thoracic limb
2) pelvic limb
What do nerve plexuses innervate?
limbs
What are individual muscles composed of?
multiple mmyotomes that overlap in forming the muscles
1) Describe innervation of trunk muscles.
2) Describe innervation of limb muscles.
1) multiple dorsal or ventral branches of spinal nerves serially innervate each individual muscle. Innervations overlap within the muscle because of myotome overlap
2) each muscle is innervated by the branch of a single regional nerve. Because of multiple myotomes per muscle, the regional nerves must contain axons from ventral branches of multiple spinal nerves. Exchange of axons among ventral branches as they forrm regional nerves produces a nerve plexus for each limb
What does myelin do?
increases rate of transmittance along the axon
