M1 Study Guide Flashcards
1
Q
define neuron
A
nerve cell that receives, processes, and transmits information via electrical and chemical signals
2
Q
define dendrite
A
spiny processes that transmit signals to the soma
3
Q
define soma
A
cell body of the neuron containing the nucleus and other organelles vital for cell function
4
Q
define axon
A
elongated processes that transmit signals away from soma
5
Q
retrograde axonal transport
A
Axon brings substances from the synapse to the soma.
Rapid transport:
- Dynein protein binds to substance (worn out organelles, tropic factors necessary for cell function) and walks up the track to soma; uses ATP.
6
Q
anterograde
A
Axon brings substances from the soma into and down axon towards synapse.
Rapid transport:
- Kinesin protein binds to substance (usually neurotransmitters) and walks down the “track” in the axon; uses ATP.
Slow transport:
- due to movement of axon cytoplasm and does not require ATP.
- used to transport proteins and structural filaments for use in the axon
7
Q
define terminal button
A
site of synapse for axon of a neuron to dendrite, soma or axon of another or multiple neurons
8
Q
define neurite
A
extension from a cell body.
ex. dendrite and axon or either
9
Q
types of neurons
A
Multipolar: most common in CNS and motor/integrator
- numerous dendrites
- pyramidal cells
Bipolar: special sensory
- one dendrite and axon
Unipolar/pseudo-unipolar: most common in PNS and primary sensory neuron
- dendrite and axon “share” a process
10
Q
define nerve
A
group of axons traveling in the PNS.
called tracts in CNS
11
Q
ganglion vs. nucleus
A
ganglion: group of cell bodies (soma) in PNS
nucleus: group of cell bodies (soma) in CNS
12
Q
different between afferent/sensory vs. efferent/motor
A
signal traveling from periphery (initiating as a receptor, or affector) to central compared to signal traveling from central to periphery where it terminates at an effector (ex. muscle, gland)
13
Q
what does CNS consist of
A
brain and spinal cord
14
Q
what does PNS consist of
A
cranial nerves and axons or spinal and peripheral nerves and neuromuscular junctions
(aka all nervous system components outside brain and spinal cord)
15
Q
define axon transport and name the 2 types
A
movement of organelles, vesicles, and secretory material (ex. neurotransmitters) throughout the neuron, especially in and out of the axon.
anterograde and retrograde
16
Q
what are the CNS neuroglia
A
Astrocytes
Microglia
Ependymal
17
Q
what are the cells involved in myelination of axons
A
oligodendrocyte (CNS)
neurolemmocytes (Schwann cell): not considered to be true glial cells bc they are found exclusive within PNS
18
Q
3 parts of nerve structure
A
- Endoneurium: connective tissue surrounds axon/nerve fiber
- Perineurium: connective tissue surrounds fascicle (collection of axons)
- Epineurium: connective tissue surrounds a nerve (contains fascicles of axons); outside cover of the nerve
19
Q
neural injury - severe damage or immediate fatal injury
A
little change in cell morphology and quickly disintegrates
20
Q
neural injury - less severe injury
A
swelling of soma, displacement of nucleus, movement of Nissl bodies (ex. RER, polyribosomes) to the periphery.
if the cell survives, it will go back to normal.
if the cell doesn’t survive, cytoplasm will turn dark and followed by disintegration of the organelles and eventually the cell.
21
Q
what are dead neurons removed by
A
Removed in CNS by microglia and in PNS by macrophages
22
Q
what happens in cases of axon injury
A
Same cell body changes occur as severe and less severe injury.
Axon injuries proximal to the soma are usually more severe for the cell compared to those that are distal.
Distal injuries only affect part of the axon
23
Q
When does degeneration commence
A
At birth because some axons are not able to find connections to other neurons.
Continues later in life due to age
24
Q
What are the 3 layers of meninges, outer to inner, and the qualities of each
A
- Dura mater: dense, fibrous connective tissue layer that is very adherent to the inside walls of cranium.
- Arachnoid: structurally continuous with the pia and contains a thick fibrous connective tissue layer.
- space between contains spider-web like structures that connect it to the pia - contains cerebrospinal fluid secreted by ependymal cells. - Pia mater: thin, delicate later of connective tissue containing collagen and elastic fibers.
- cerebral vasculature passes through this layer
25
what are the dural deflections
Falx cerebri: separates right and left cerebral hemisphere.
Tentorium cerebelli: separates occipital lobe from underlying cerebellum.
26
What are the 3 hematomas
1. Epidural: "above" dura
- shearing of artery (middle meningeal artery in pterion most likely culprit).
- high hydrostatic pressure of arterial blood allows for these to progress fast
2. Subdural: "beneath" dura.
- shearing of vein (ex. emissary veins that pass through the skull and return blood from scalp back to heart more likely involved with this type of hematoma)
- lower hydrostatic pressure in veins compared to arteries - progress much more slowly than epidurals.
3. Subarachnoid: typically occur secondary to a ruptured cerebral aneurysm within subarachnoid space.
- blood mixes with CSF and will raise intracranial pressure.
27
what are the 2 parts of the PNS
Somatic - voluntary contol.
Autonomic - involuntary
28
specific structures and nerve sections of the PNS in general
Neurons: dendrites, axons, soma
Ganglia: somatosensory and autonomic
29
PNS schema
1. Specialized neurons called receptors (affectors) detect stimuli from inside and outside the body and send an electrical signal in response up an afferent pathway towards CNS.
2. Electrical signal travels along a chain of neurons through PNS.
3. Afferent signals from all over the body enter CNS and are organized in a way that yields our perceptions (correlation of signals) and these perceptions are stored in the CNS as memories.
4. As a reaction to our sensory perceptions and memories, CNS sends out efferent electrical signals along neurons.
5. Efferent signals travel through neurons in PNS, ending upon muscles and glands (effectors).
- CNS coordinates these different signals to assure the actions of the muscles and glands work together toward a common goal.
30
how many cranial nerves are there and what are the types (motor/sensory)
12 pairs of cranial nerves:
- 5 motor only
- 3 sensory only
- 4 both
31
how many pairs of spinal nerves are there and for what section of the spine
31 pairs of spinal nerves:
- 8 pairs cervical
- 12 pairs thoracic
- 5 pairs lumbar
- 5 pairs sacral
- 1 pair coccygeal.
all carry motor and sensory except C1 (motor only) and coccygeal (sensory only)
32
what are dorsal and ventral roots
dorsal roots: sensory axons of GSA and GVA fibers to CNS
ventral roots: motor axons of GSE and some GVE from CNS
33
what are GVE fibers and where are they found
convey autonomic info.
only found in ventral roots of the thoracic and upper lumber (thoracolumbar --> sympathetic) and sacral (craniosacral --> parasympathetic) spinal nerves
34
where is dorsal root ganglion located
(soma of sensory neurons --> pseudounipolar type).
located adjacent to spinal cord and is linked to the cord via the dorsal root of a spinal nerve
35
what are sympathetic (paravertebral) ganglia and where are they found
chain of autonomic ganglia lateral to the vertebral column (sympathetic division of AND of the PNS
36
what are the white and gray rami communicans and where are they found
neural fibers of the sympathetic division of ANS that communicate between sympathetic trunk and spinal nerve.
White rami communicans:
- preganglionic sympathetic fibers of preganglionic neurons
- axons more myelinated than those of the postganglionic sympathetic fiber as the former emerge from CNS.
Gray rami communicans: contain postganglionic sympathetic fibers of ganglionic neurons
- called gray because the fibers that pass through are less myelinated than preganglionic axons that pass through white rami communicans.
37
what are prevertebral ganglia and what do they contain
aka collateral sympathetic ganglion.
contain synapses of preganglionic and ganglionic sympathetic fibers that do not synapse with the sympathetic trunk.
series of autonomic ganglia anterior the vertebral column.
postganglionic sympathetic fibers exiting the prevertebral ganglia innervate viscera in the abdominal and pelvic cavities.
38
what are dermatomes
Each spinal nerve carries somatic sensory info from a specific area of skin on the surface of the body.
Dermatome: area of skin supplied by a single spinal cord level or on one side by a single spinal nerve (not cranial nerve).
There is overlap in distribution of dermatomes.
Testing touch in these autonomous zones in a conscious patient can be used to localize lesions to a specific spinal nerve or specific level in spinal cord.
39
what are myotomes
Myotome: portion of skeletal muscle innervated by a single spinal cord level or one one side by single spinal nerve.
More difficult to isolate to a single spinal nerve because skeletal muscles are usually innervated by nerves derived from more than one spinal cord level
40
what are the functions of nerve plexuses
Join intersecting nerves and prove routing for nerves in transit.
Provide diffuse local innervation to a structure.
41
What is the one region that does not have the presence of a nerve plexus
thoracic region
42
what is a spinal nerve plexus
formed by extensive branching and cross-joining of neighboring anterior rami.
individual nerve fibers do not synapse upon each other or (usually) branch themselves
43
what are the key SOMATIC plexuses
Cervical plexus: neck and back of head.
- formed from anterior rami C1 - C4.
Brachial plexus: anterior rami C5 - T1.
- serves chest, shoulder, arms, hands.
Lumbar, sacral and coccygeal plexuses
44
when is the superior portion of brachial plexus injured and what are the signs
injured when head and neck pulled away from the arm.
Clinical sign: "waiter tip" position along with some sensory sensation in the arm - arm position due to inability to flex the arm
45
when is the inferior portion of the plexus injured and what are the signs
injured from pulling of arm that causes problems with muscles of the hand.
Clinical sign: "claw grip" presentation
46
what pathway is the ANS
visceral efferent pathway
47
where does the ANS receive information from and what is it about
Receives info from the hypothalamus deep in the brain in response to visceral afferent information receptors or from other parts of the brain
48
what type of chain is the autonomic pathway normally comprised of
three - neuron chain
49
what chain do somatic efferents consist of
two - neuron chain.
contain one upper- and one lower-motor neuron.
50
where is upper-order motor neuron found
from the deep brain (hypothalamus) to CNS nuclei (cranial nerve nucleus or spinal cord nucleus) where it synapses with the first lower-order motor neuron
51
where is the soma and axons of the first lower-order motor neuron (preganglionic neuron)
the soma is within the CNS.
their axons exit the CNS into the PNS, where a synapse occurs with the second lower-motor neuron (ganglionic neuron) in an autonomic ganglion
52
what occurs within the PNS autonomic ganglion
synapse of the preganglionic and ganglionic neuron, as well as the soma of the ganglionic neuron
53
what are the qualities of the axon of the ganglionic axon and what does it do
short and poorly/unmyelinated.
innervates effector
54
why are axons of parasympathetic ganglionic neurons very short and unmyelinated
because of proximity to effector
55
what are the subdivisions of the ANS
Sympathetic or thoracolumbar: helps the person prepare for emergencies or times of high stress
- fight or flight.
Parasympathetic or craniosacral: helps conserve and store energy
- rest and digest
56
where are autonomic ganglia found and where do they snapse
found along the course of efferent nerve fibers of the ANS.
ANS preganglionic axons enter the ganglia and synapse on a nerve cell body of another neuron (ganglionic) within
57
where are autonomic sympathetic ganglia and autonomic parasympathetic ganglia found
sympathetic ganglia: typically near CNS
parasympathetic ganglia: near structure of innervation
58
where do all preganglionic sympathetic nerve fibers exit from
spinal cord anteriorly/ventrally from T1 to L2 ("thoracolumbar")
59
where do preganglionic parasympathetic nerve fibers leave from
cranium (via cranial nerves) or from the sacral portion of the spinal cord ("craniosacral")
60
where do efferent preganglionic sympathetic axons have their preganglionic cell bodies
within intermediate horn of gray matter of the spinal cord, which runs from T1 to L2
61
upon entering the sympathetic chain, there are multiple destinations for the preganglionic sympathetic axon. what are they?
1. immediately synapse with a postganglionic neuron
- postganglionic axon then exits via grey ramus into spinal nerve at the same spinal level, then to destination.
2. ascend or descend in the sympathetic chain and syanpse upon a neuron there
- postganglionic axons then exit the grey ramus
3. pass through sympathetic chain without synapsing and synapse in one of several ganglia that make up the prevertebral ganglia
- postganglionic sympathetic axons will innervate a GI tract, urinary, or reproductive organ
62
where do preganglionic parasympathetic axons arise from
1. cranial nerve nuclei and exit the CNS and into PNS as 4 of the cranial nerves - CN III, VII, IX, and X
2. cell group and exiting the CNS as spinal nerves at the S2 - S4 level of the spinal column
63
where are the soma of ganglionic parasympathetic neurons found
in the parasympathetic ganglion
64
true or false: there is a parasympathetic trunk
false
65
efferent sympathetic and parasympathetic functions of the eye - iris
efferent sympathetic: dilation of pupil (mydriasis)
efferent parasympathetic: constriction of pupil (miosis)
66
efferent sympathetic and parasympathetic functions of the eye - ciliary muscle
efferent sympathetic: relaxation of accommodation
efferent parasympathetic: activation of accommodation
67
efferent sympathetic and parasympathetic functions of the salivary glands
efferent sympathetic: decreased salivation
efferent parasympathetic: increased salivation
68
efferent sympathetic and parasympathetic functions of the sweat glands
efferent sympathetic: increased sweat (diaphoresis)
efferent parasympathetic: no innervation
69
efferent sympathetic and parasympathetic functions of the heart
efferent sympathetic: increased cardiac contraction force and rate (tachycardia)
efferent parasympathetic: decreased cardiac contraction force and rate (bradycardia)
70
efferent sympathetic and parasympathetic functions of the lungs, bladder, GI tract
efferent sympathetic: inhibition of smooth muscle in lungs (relaxation), bladder (urine retention), GI tract (constipation); contracts sphincters
efferent parasympathetic: stimulation of smooth muscle action in lung (constriction), bladder (urination), GI tract (diarrhea); relaxed sphincters
71
efferent sympathetic and parasympathetic functions of the peripheral blood vessels
efferent sympathetic: constriction of blood vessels of the skin
efferent parasympathetic: no innervation for most
72
what is the enteric nervous system
special case of the ANS.
composed of 2 plexuses of nerve cells and fibers that surround the GI tract from esophagus to anal canal
73
where is the submucosal (Meissner) plexus and what is it involved in
deepest of the 2 enteric plexuses.
heavily involved in secretion of substances into the lumen of the GI organs, absorption and blood flow in GI wall, and minor roles in GI motility
74
where is the myenteric (auerback) plexus and what is it responsible for
located between major muscle layers.
mainly responsible for GI motility, but also plays roles in blood flow control and minor roles in secretion and absorption
75
what does autonomic input do to the activity of the enteric nervous system
modulates
76
does afferent mean to or from the cns
to cns
77
does efferent mean to or from cns
away from cns
78
what does the proencephalon (forebrain) consist of and what cranial nerves does it contain
Telecephalon (cerebrum)
- olfactory (I): sensory only
Diencephalon ('deep brain' and include hypothalamus, thalamus, epithalamus)
- optic (II): sensory only
79
what is the brainstem comprised of
mesencephalon
rhombencephalon
80
what does the mesencephalon (midbrain) serve as and what cranial nerves does it contain
serves as anatomical connector between forebrain and hindbrain.
first section of brainstem relative to proencephalon.
Oculomotor (III): motor only
Trochlear (IV): motor only
81
what are the 2 parts of the rhombencephalon (hindbrain)
Metencephalon (pons and cerebellum)
Myelencephalon (medulla)
82
What cranial nerves does the metencephalon consist of
Trigeminal (V): mixed.
- ophthalmic (V1): sensory only
- maxillary (V2): sensory only
- mandibular (V3): mixed
Abducens (VI): motor only
Facial (VII): mixed
83
what cranial nerves does the myelencephalon consist of
Vestibulocochlear (VIII): sensory only.
Glossophayrngeal (IX): mixed.
Vagus (X): mixed.
Spinal accessory (XI): motor only.
Hypoglossal (XII): motor only.
84
what information do GVE fibers carry
autonomic information
85
What fiber types are only associated with the cranial nerves
Special:
- SA
- SVA
- SVE
86
What spinal nerves contain general fibers
GSA: all except first set of cervical spinal nerves, C1 (C1 is motor).
GSE: all except one set of coccygeal spinal nerves (coccygeal is sensory).
GVA:
