Exam 1: Flashcards
(124 cards)
1
Q
3 neuronal shapes
A
multipolar, bipolar, unipolar
2
Q
multipolar neurons
A
majority in vertebrates
multiple dendritic projections
3
Q
bipolar neuron example
A
olfactory receptor neuron
4
Q
unipolar neurons
A
common in vertebrates
DRG neurons are an example
5
Q
4 neuron classifications based on connections
A
sensory neurons
motor neurons
interneurons
projection neurons
6
Q
grey vs white matter
A
grey: cell bodies and dendrites
white: axons
7
Q
dendritic spines
A
receive excitatory input
8
Q
Sites of synaptic contracts (4)
A
AD: axodendritic (axon synapse on dendrite)
AS: axosomatic
DD: dendrodendritic
AA: axoaxonic
9
Q
astrocytes: role and types
A
structural/metabolic support, injury response
types: protoplasmic (found in grey matter), fibrous (white matter), radial glia (during development, guide growing axons)
10
Q
Ependymal cells
A
line brain ventricles
produce CSF
11
Q
peak risk for birth defects is at how many weeks
A
3-5 weeks
12
Q
day 18:
A
13
Q
bilaminar disc formation (before neurulation
A
blastocyst (epiblast/hypoblasm) attach to uterine wall
epiblasm forms primitive streak, which eventually forms mesoderm
14
Q
gastrulation
A
epiblasm cells migrate through primitive streak
endoderm cells displace hypoblasm
mesoderm forms b/w endoderm and ectoderm
15
Q
week 3 marks ____
A
beginning of primary neurulation
16
Q
what happens during week 3
A
neural plate forms from ectoderm, separates
notochord forms from mesoderm, separates
neural crest cells forms from edge of ectoderm, separates
17
Q
when is primary neurulation completed
A
week 4
18
Q
week 4: 3 vesicles
A
prosencephalon, mesencephalon, rhombencephalon
19
Q
week 4
A
20
Q
what happens during week 4
A
ectoderm begins to fuse into single layer
neural crest cells separate
neural tube begins to fuse (rostral end closes first)
3 primary vesicles form
somites form (future vertebrae)
21
Q
secondary neurulation completed by:
A
week 7
total fusion
22
Q
what happens during secondary neurulation
A
medullary cord exists as mass of cells in tail bud
caudal pore fuses, forming secondary cavity and medullary cord
secondary cavity extends into medullary cord and forms secondary neural tube
23
Q
two major signaling molecules in neural tube development
A
bone morphogenetic proteins: produced by ectoderm
sonic hedgehog: produced by notochord
24
Q
A
25
alar vs basal plate
separated by what
**alar:** sensory processing
**basal:** motor processing
separated by **sulcus limitans**
26
cranial placodes
derived from ectoderm
collaberate w/ neural crest cells to form cranial nerves
27
2 flexures at the end of week 4
**cervical flexure:** straightens in adulthood
**cephalic flexure:** present in adults, at level of midbrain
prosencephalon, mesencephalon, prosencephalon
28
week 6 vesicles + flexures
prosencephalon → **telencephalon, diencephalon**
mesencephalon → **mesencephalon**
rhombencephalon → **metencephalon, myelencephalon**
cephalic, pontine, cervical flexures
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results of pontine flexure
at level of brainstem
forms thin membrane that becomes roof of 4th ventricle
sensory nuclei go from north to lateral
motor nuclei go from south to medial
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rhombic lips
alar plate thickenings in rostral metencephalon (future pons/cerebellum)
leads to development of cerebellum
31
cortical growth: rapid growth induces \_\_\_\_
rotation:
cortex grows in c-shape
massive burst in neuron proliferation during months 3-5
32
results of rapid cortical growth
telencephalon starts out separate but continuous w/ diencephalon
as cortex grows, telencephalon fuses w/ diencephalon
insular cortex becomes encased
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choroid plexus
formed by blood vessels invaginating ependymal cells of ventricle lining
produces CSG
mostly in lateral ventricles, some in 3rd/4th
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when do myelin sheaths develop
mostly postnatally
35
craniorachischisis
fatal
complete failure of neural tube to fuse
caused by defective closure on normal neurulation initiation site
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myelomeningocele (spinal bifida)
failed closure of **_caudal neural tube_**
associated w/ **Chiari type 2 malformation:** hydrocephalus (increased pressure) causes cerebellum and brainstem to be pushed into spinal cavity
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anencephaly
failed closure of **_rostral neural tube_**
most of cerebral hemisphere may be missing
disorganized neural tissue, mixed w/ choroid plexus
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holoprosencephaly
caused by trisomy 13 or signaling molecule gene mutations
failure of prosencephalon to separate into bilateral telencephalon and diencephalon
longitudinal fissure absent
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heterotopias
displaced grey matter due to cells not migrating from ventricle to cortex
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lissencephaly
smooth brain
sulci absent (except for lateral sulcus)
cell migration problem
41
Chiari II-Polygyria
busy gyral pattern
associated w/ hydrocephalus
small cerebellum and brainstem, cerebellum herniates into spinal cavity
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secondary neurons (interneurons
input from ipsilateral 1o sensory neuron
projects to lower motor neurons
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reflex arc
1o sensory neuron stimulates 2o interneuron, which stimulates motor neuron; also sends signal to somatosensory cortex via thalamus and to cerebellum
44
spinothalamic pathway
crosses in spinal cord
pain/temperature
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Posterior-Column-Medial Lemniscus pathway
crosses in medulla
touch/proprioception
46
spinal cerebellar pathway
uncrossed sensory info
cerebellum receives input from ipsilateral side of body
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corticospinal tract (CST)
crossed pathway
voluntary motor activity, driven by upper motor neurons in 1o motor cortex
48
cerebellum and voluntary motor activity
constantly makes adjustments
cerebellum → thalamus → 1o motor cortex → basal pons → cerebellum
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anterior lobe of cerebellum
spinal afferents (output to spine)
coordination of trunk/limb movement
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posterior lobe of cerebellum
cortical afferents (via pontine nuclei)
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vermis of cerebellum
cortical afferents
sense of touch and proprioception
52
flocculonodular lobe of cerebellum
vestibular afferents
coordination of eye movements
53
2 ways meninges stabilizes CNS
mechanical suspension (membranes connected to skull)
buoyant suspension (in CSF)
54
3 layers of meninges and spaces
**dura mater**
**arachnoid**
subarachnoid space: blood vessels, CSF, arachnoid trabecula
**pia mater**
55
dura mater: layers and spaces
**periosteal** (surface in contact w/ skull) and **meningial**
potential spaces (related to conditions): **epidural** (b/w brain and bone) and **subdural** (b/w dura and arachnoid)
56
what are dura folds
Create double layers of dura and separate intracranial components
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examples of dura folds:
**Falx Cerebri** (b/w two hemispheres)
**Tentorium cerebelli** (b/w hemispheres and cerebellum)
**Falx Cerebelli** (partially separates two
hemispheres)
**Diaphrama sellae** (separates brain from pituitary)
58
major pathway of CSF in sinuses
superior sagittal sinus → confluence of the sinuses → transverse sinus → sigmoid sinus → drains into internal jugular vein
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60
**Arachnoid trabeculae**:
help brain suspension within meninges (connect arachnoid to pia
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Arachnoid villi/granulations:
reabsorption of CSF into venous system
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Subarachnoid Cisterns:
spaces between arachnoid and pia
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pia mater
covers all external surface of CNS
contains CSF to subarachnoid space
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differences in meninges b/w spinal cord and brain
there's no bone (periosteal component)
space b/w meninges and vertebrae (**epidural space**)
pia creates **denticulate ligaments** that anchor spinal cord to arachnoid
65
where does spinal dura end
where does spinal cord end
spinal dura: ends 2nd sacral vertebrae
spinal cord: ends 2nd lumbar vertebrae
space b/w these is **lumbar cistern** which contains CSF and no nerves
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epidural hematoma
meningeal artery bleed/damage – bleeding occurs between
periosteum and the skull.
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subdural hematoma
venous bleed/damage – bleeding occurs as vein penetrates arachnoid entering dural sinus
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how do lateral ventricles communicate w/ third ventricle
interventricular foramen of monroe
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how do 3rd and 4th ventricle communicate
cerebral aqueduct of sylvius
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how does 4th ventricle communcate w/ CSF filled spaces in spinal cord and outside brain
foramina of magendie and foramina of lushka
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3rd ventricle is bordered by what
ventrally: hypothalamus
dorsally: thalamus
anterior: lamina terminalis
72
4th ventricle is bordered by what
posterior: cerebellum
anterior: pons/medulla
73
where is choroid plexus found
mostly in lateral ventricles (enlarged in atrium, termed **glomus** of choroid plexus)
some found in 3rd and 4th ventricles
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fissures of choroid plexus
**choroid fissure** and **transverse fissure**
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choroid plexus structure
3 layers:
1. choroid capillary
2. scattered pial cells
3. choroid epithelium
76
write specific path of CSF flow
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CSF functions
mechanical support (buoyancy)
spatial buffering (space for blood to move in or out)
78
blood vessel density differences in brain
blood vessel density is greater in grey matter than white matter
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regulation of blood flow in brain
**inside range**: cerebral vessels dilate as pressure decreases, keeping flow constant
**outside range:** increases and decreases in pressure cause increases or decreases in flow
80
blood supply to brain: main arteries
**internal carotid arteries**: supply most of telencephalon and diencephalon
**vertebral arteries:** supply brainstem/spinal cord, cerebellum, diencephalon, occipital/temporal lobes
81
middle cerebral artery supplies blood where
along lateral fissure
blood supply to **insula**
82
what does motor homunculus look like
83
what are 1, 2, 3, 4, 9, and 11
1= internal carotid
2=middle cerebral (along lateral fissure)
3=anterior cerebral (along longitudinal fissure)
4=posterior communicating
11= posterior cerebral
9=basilar artery
84
Lenticulostriate Arteries
branches off middle cerebral artery
often involved in strokes, flow to motor regions
85
types of strokes
**thrombus:** blood clot
**embolus:** foreign matter along bloodstream
86
TIA
transient ischemic attack
deficits persist for a few hours then recover completely
87
aneurysms + how they can cause neurological deficits
balloon swelling of arterial walls
grow/size, push brain structures
rupture, cause subarachnoid hemmorhage
88
arteriovenous malformation (AVM)
can steal blood away from brain tissue or rupture
89
BBB includes
arachnoid layer (tight junctions)
blood-CSF layer
tight junctions b/w endothelial cells of blood capillaries
90
circumventricular organs
where BBB contains fenestrated capillaries
1. subfornical organ
2. lamina terminalis
3. pineal gland
4. median eminence (base of hypothalamus)
5. area postrema
91
most superficial veins empty into
superior sagittal sinus SSS
92
most deep veins empty into
straight sinus
93
types of receptors
IPE
* **interoceptos:** monitor events w/in body
* **proprioceptors:** monitor position of body in space
* **exteroceptors:** monitor stimuli outside of body (touch, hearing vision)
94
receptive fields of receptors in hand vs harm
smaller receptive field in fingers than in wrist or arm
fingers have greater density of receptors, thus higher spatial resolution
95
intensity of a stimulus....
is determined by size and duration of receptor potentials produced
96
example of slow and rapid adapting receptors
slowly adapting: body position
rapidly adapting: change/movement of stimuli
97
mechanoreceptor
encapsulated types
* layered:
* **pacinian corpuscle:** rapid adapting; vibration
* **meissner corpuscle:** rapid adapting; touch
* thin capsule:
* **ruffini ending:** slow adapting; pressure
98
mechanoreceptor
noncapsulated types
* accessory structures around hairs: rapid adapting; touch
* **merkel endings**: slow adapting; maintained pressure
* **free nerve endings:** pain/temp/itch/touch
99
nociceptors
free nerve endings
pain/temp detection
acute pain: Aδ
slow/aching pain: C fibers
100
thermoreceptors
free nerve endings
ion channels respond to temp changes
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2 types of encapsulated receptors in muscles
**muscle spindles:** detect muscle length and proprioception
**golgi tendon organs:** detect muscle tension
102
cell bodies of peripheral nerves are where
in dorsal root ganglion
1 DRG per segment of spinal cord
103
Aδ fibers
fast/acute pain
104
Aα fibers
to extrafusal muscle fibers
105
Aγ
to intrafusal muscle fibers
106
spinal cord segments
31:
8 cervical
12 thoracic
5 lumbar
5 sacral
107
each segment of spinal cord:
each segment innervates a dermatome
each segment gives rise to single **spinal nerve** on each side
108
enlargements of spinal cord
cervical enlargement (C5-T1): upper extremeties
lumbar enlargement (L2-S3): lower extremeties
109
cervical nerves vs noncervical nerves leave vertebral canal
cervical nerves leave vertebral canal above corresponding vertebra
noncervical nerves leaves vertebral canal below corresponding vertebra
110
anterior horn of grey matter
cells of motor neurons
loss of these neurons causes complete paralysis
111
alpha motor neurons
each group innervates an individual muscle
112
gamma motor neurons
innervate intrafusal muscle fibers of muscle spindles
113
alpha motor neurons that innervate axial muscles are \_\_\_\_
medial to α-motor neurons that innervate limb muscles
114
gray matter:
intermediolateral cell column
location of preganglionic sympathetic neurons
115
clarke's nucleus
relay nucleus to cerebellum, plays role in proprioception
116
muscle stretch reflex
tap patellar tendon, stretch quadriceps, excitation of muscle spindle (1a fibers), excitation of α motor neuron, quadriceps contract
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reflexes: reciprocal inhibiton
reflex activity in a given muscle produces similar activity in its ipsilateral synergists and opposite activity in ipsilateral antagonists
ex: in patellar tendon reflex, excitation of quadriceps but also inhibition of hamstring
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flexor (pain) reflex
reflex normally held in partial inhibited state
involves multiple muscles: primary afferents extends to multiple segments; flexor response includes multiple interneurons
Aδ
119
reflexes: crossed effects
as one leg flexes and withdraws, other leg extends to better support body weight
120
receptors can be divided by stimulus they are most sensitive to, called \_\_\_\_
adequate stimulus
121
type of receptor stimulated defines the _____ of the sensation that is experienced
nature (modality)
122
each sensory modality has a series of associated \_\_\_\_\_
submodalities or qualities
ex: skin stimuli can feel like light touch, pressure, tickle
123
receptors encode ____ and ____ of stimuli
intensity and duration
124
\_\_\_\_ are abundant in the skin of fingertips, and they, along w/ ____ are largely responsible for fine tactile discriminations w/ our fingertips
meissner corpuscles
merkel endings
