Unit 5 Nervous Flashcards
1
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Central nervous system
A
Brain and spinal cord (inside dorsal bodycavity)
2
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Peripheral nervous system
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12 cranial nerves, 31 spinal nerves
3
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Glial cells
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‘Glue’ = support cells of neurons
4
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Neuron
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Major functional cell, main communicator
5
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Soma
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Cell body of neuron ( w/ nucleus etc.)
6
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Process
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Extensions from soma
7
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Axon
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Processes that connects neuron to its target
8
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Dendrite
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Processes that receive info. (Mainly from other neurons)
9
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Gray matter
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.neuron cell bodies, dendrites, unmyelinated axons
10
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White matter
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Axons W/ fatty coatings (myelin), myelinated axons
11
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Nucleus
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Found in CNS
12
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Ganglion
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Cluster of cell bodies in PNS
13
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Node of ranvier
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Gap in myelin sheath
14
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Axon hillock
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Initial segment
15
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Axoplasm
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Cytoplasm inside axon
16
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Nissl bodies
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Highly developed rough Er of soma
17
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Unipolar(type of neuron)
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1 process from soma (most sensory neurons)
18
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Bipolar(type of neuron)
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2 processes, rare (retina, olfaction)
19
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Multipolar (type of neuron)
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Several processes, most common by far(allmotor and association neurons)
20
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How many glial cells in CNS?
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4
21
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Astrocytes (glial)
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Maintain extracellular fluid (mop up ions, neurotransmitters); help from blood-brain barrier, least permeable
22
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Ollgodendrocytes (glial)
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Provides myelin of CNS
23
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Migroglial cells (glial)
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Resident macrophages- gobble up debris
24
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Ependymal (glial)
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Help form cerebral spinal fluid from blood plasma; line ventricles and cover each choroid plexus
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Ventricles
Fluid filled cavities of CNS
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Choroid plexus
Knot of capillaries w/ wehtricles
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How many glial cells in PNS?
2
28
Satellite cells (glial/PNS)
Similar to astrocytes (no blood barrier though)
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Schwann cells (glial/PNS)
Myelin sheath of PNS
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Nerves
Bundles axons of PNS
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Tracts
Bundled axons in CNS
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Nervous system functions
Sensory, integration, response
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Sensory ( nervous func.)
Sense changes/ stimuli in the env't (internaland external)
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Integration (nervous func.)
Associate stimuli and memories/learning/ emotion to determine responses
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Response (nervous func.)
Send response instructions to effectors (glands/muscles) = motor function
36
Somatic nervous system
Conscious perception and voluntary response, effectors = skeletal muscle
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Automatic nervous system
Involuntary control of most organ systems; effectors = smooth + cardiac muscle and glands
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Parasympathetic
Rest and digest
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Sympathetic
Fight or flight
40
Enteric nervous system
Autonomous func. Of digestive tract, can operate independent of CNS, contains more neurons of spinal cord
41
Transmembrane proteins and APs
To separate Lons and generate action potentials, transmembrane proteins required
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What is pumped into sodium-potassium pump?
3 na+ pumped out of cell; 2k pumped in
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Sodium potassium pump
Responsible for na+ as major extracellular cation, k+ major intracellular cation,ATP required, required to maintain restingmembrane potential
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Ion channels
Ion flow by diffusion
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Electrochemical exclusion ( ion channels)
Channels allow cations or anions,not both
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Size exclusion (ion channels)
Pore size can exclude some ions
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Nonspecific channels (ion channels)
Allow multiple ions to diffuse
48
Gated channels (ion channels)
Must be unlinked to open
49
Ligand - gated channels
Gated channels, molecules/neurotransmitter binds to channel, channel open, allow diffuse
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Mechanically gated channels
Distortion of membrane opens channel, pressure, temp.
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Voltage gated channel
Local depolarization (change in voltage)opens
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Leakage channels
Open and close at random, neurons have both k+ and na+ leakage channels, Na and K must work constantly
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Resting membrane potential
Build up of Na + ions outside, large anions ( proteins, phosphates) inside cell, k+ leaks out, attracts anions too big and wrong charge to pass, na-k pump maintains gradients
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AP step 1 and 2
① stimulus causes gated Na channels to open, membrane depolarizes
② if enough Na enters @axon hillock, threshol is reached
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Depolarize
Voltage moves closer to zero,membrane becomes ↓ polarized
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AP step 3 and 4
③ voltage gated Na channels open
④ Na floods into cell, depolarization continues to + 30mv
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AP steps 5 and 6
⑤ voltage gated Na channels close / inactivate
⑥ voltage gated k channels open and K floods out of the cell
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Repolarize
Voltage moves back toward RMP
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AP steps 7 and 8
⑦ membrane repolarizes
⑧ voltage gated K channels close
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AP steps 9 and 10
⑨ membrane hyperpolarizes
10. Voltage gated k channels close
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Hyperpolarize
Voltage goes below RMP, membrane over polarized
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Refectory periods
AP only occur 1 at a time,
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Absolute refectory period
No new AP can be initiated
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Relative refectory period
AP possible, but stimulus> than normal threshold
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Voltage gated Na channels have 2 gates
Activation/inactivation gate
- both gates must 'reset' before next AP possible
-Absolute refectory period = activation
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① activation gate
Opens at threshold, Na floods in=depolarization
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② inactivation gale
Closes immediately after, Na blocked,k channels open, k floods out= repolarization
- stop ion flow
68
Un myelinated neurons ( AP propagation )
Continuous conduction
- Na entering triggers adjacent Na gates to open
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Myelinated neurons (ap propagation)
Saltatory conduction
- Na gates at nodes of ranvier,myelin prevents ion leakage, ap's leap between segments
- saltatory 10X faster than continuous
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Speed ↑ w/ axon diameter =
Less resistance
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Graded potentials
Depend on stimulus strength, AP'S are all or none and all the same, changes in membrane potential that vary m size
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Strong stimulus =
↑ graded potential
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Generator potentials
Graded potentials or unipolar sensory neuron dendrites
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Receptor potentials
Graded potentials of special sensory cells (like rods and cones) that communicate W/ sensory neurons
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What do neurotransmitters generate?
Post synaptic potentials ( PSPs)
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Excitatory post synaptic potentials(EPSPs)
- Depolarizing (closer to threshold) Na or ca enters
- depolarize membrane
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Inhibitory post synaptic potentials (IPSP)
Hyperpolarizes (away from threshold) K exits or Cl enters
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Where does graded potential summate?
At axon hillock(initial segment)
- If graded potentials summate to threshold, AP generated
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Summation
Graded potentials 'added up' @ axon hillock,
Combine to reach threshold of AP
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Temporal summation
Rapid succession of excitatory potentials lead to threshold
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Spinal summation
Excitatory potential
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The synapse - "connection' between cells
2 types:
Electrical and chemical synapse
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Electrical synapse
Gap junctions directly connect neurons (rare)
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Chemical synapse
Junction between neurons where signals are transmitted vid the release of chemical messengers called neurotransmitters
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Synapse steps 1,2,3
① AP arrives at synaptic end bulb
② voltage -gated ca channels open - Ca enters
③ synapse vesicles motor to presynaptic membrane
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Synapse steps 4 and 5
④ neurotransmitters ↑ into synapse cleft via exocytosis
⑤ neurotransmitters diffuse across cleft, bind to receptors on post synaptic membrane
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Synapse steps 6 and 7
⑥ receptors change conformation
⑦ neurotransmitters break↓ or re-uptake
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Ionotropic receptor ( ligand gated)
Neurotransmitter binds, channel opens, ions flow
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Metabotropic receptor
Neurotransmitter binds-metabolism changes ensue
- G protein coupled receptors that active second messenger systems
90
What is G protein activated by?
By GTP and moves to effector protein
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What does effector protein generate?
Generates 2nd messenger (like camp)
92
What does 2nd messenger cause?
Cause changes (open or close ion channels, activate or deactivate enzymes, change gene transcription)
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Where does nervous system develop?
Develop from ectoderm
94
Remnants of hollow center of neural tube =
CSF filled w/ventricles and central canal
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Spinal bitida
Failure of neural tube to close
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Occulata(spinal bifida)
'Hidden' - vert. Fail to fuse
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Meningocele (spinal bitida)
Meninges (protective membranes) protrude
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Myelomeningocele ( spinal bifida)
Meninges + spinal nerve
99
Cerebrum
Largest region of brain
- frontal, parietal, temporal, and occipital, and major landmarks like central sulcus and lateral sulcus
100
Cerebral cortex
Wrinkly outer few mm of grey matter
- primary sensory, association, integration
101
Central hemisphere
Right and left symmetrical regions connected by corpus callous
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Cortex divided into 4 (or 5) lobes
- Frontal lobe, parietal lobe, temporal, occipital
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Gyri and sulci (sulcus )
Gyros = ridges, sulcus = grooves
Lobes defined by prominent gyro and sulcus
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Central sulcus
Frontal lobe anterior, parietal lobe posterior
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Lateral sulcus
Temporal lobe inferior, occipital lobe posterior
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5th lobe: deep to lateral sulcus
Insult
107
Cerebral contains 3 types of processing regions:
Primary, association, and integration
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Primary cortical areas
Sensory info initially processed, or motor commands emerge
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Association cortical areas
Adjacent primary areas further process medically
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Multimodal integration cortical areas
Found where modality- specific regions meet; process multiple modalities to unify experience
111
Broadman'S areas =
Specialized cortex regions
112
Primary motor cortex (broadman's)
Final motor commands, originate here (precentral gyros)
113
Primary somatosensory (broadmans)
Perception of general senses
114
Primary visual (broadmans)
Visual perception (posterior - medial occipital lobe)
115
Premotor cortex (broadmans)
Muscle memory, planned movements.
116
Somatosensory association cortex (broadmans)
Sensory memories
117
Visual association (broadmans)
Visual memories
118
Primary auditory (broadmans)
Sound perception
119
Auditory association(broadmans)
Sound memories
120
Broca'S area (broadman's)
Language production,muscles for speech
121
Wernicke'S area (broadmans)
Understanding speech, learning vocab.
122
Prefrontal cortex (broadmans)
Logic, personality, consciousness, short-term memory (anterior integration area)
123
Frontal eye field (broadmans)
Eye movement
124
Subcortical nuclei of the cerebrum
Hippocampus, amygdala, basal forebrain
125
Hippocampus and amygdala
Emotional response, long-term, memory, major components of lambic system( links autonomic to consciousness motivation)
126
Basal forebralh
Produces ACH-moderates overall activity of cortex wakefulness
127
Conus medullaris (spinal cord)
End of cord (=L1 - L2)
128
Caudal equine (spinal cord)
Roots of lower lumbar, sacral, coccygeal nerves
129
Filum terminala (spinal cord)
Extension of pla mater, anchors cord
130
Spinal cord: gray matter
Dorsal (posterior) horn, ventral (anterior) horn, lateral horn
131
Dorsal (posterior) horn
Entering sensory axons and processing
132
Ventral (anterior) horn
Somatic motor neuron cell bodies
133
Lateral horn and sacral lateral horn
Autonomic motor neurons ( T 1- L2 = sympathetic motor,
Sacral lateral horn= parasympathetic motor (autonomic)
134
Spinal cord: whole matter
Posterior (dorsal) columns, lateral columns, anterior (ventral) columns
135
Posterior (dorsal) columns
All ascending (sensory) tracts
136
Lateral columns
Ascending + descending (motor)
137
Anterior (ventral) columns
Ascending + descending
138
Dorsal column system (ascending sensory pathways)
( Aka dorsal column) - medial leminscus pathway
139
What does 1st order neuron ascend w/? (Ascending sensory pathways)
Ascends via fascicles cune atussupper trunk, arms, neck) or fascicles gracilis (lower trunk, legs)
140
Synapse w/ 2nd order neuron? (Ascending sensory pathways)
WI 2nd order neuron in medulla and decussates (crosses overs
141
2nd order ascends? (Ascending sensors pathways)
Ascends via medial lemnisces synapses WI 3rd neuron in thalamus
142
3rd order to cortex? (Ascending sensors pathways)
Fine touch and proprocopion (body position)
143
Spinothalamic tract
1st order neuron synapses w/ 2nd order neuron in dorsal horn and decessates
- 2nd order ascends via spinothalamic (ventral or lateral)
144
Sensory homunculus
Contralateral 'map' of cortex projection n primary
- Perception depends on where cortex is stimulated-.
145
Spinocerebellar tract (sensory homunculus)
1st order neuron synapses w/ 2nd order neuron in dorsal horn
- 2nd order ascends, synapses on same Side (spilateral) in cerebellum
- no 3rd neuron
146
Corticosinal tract (descending pathway)
Large upper motor neurons of primary motor cortex descend to brain stem(canal motor) or spinal cord
- synapse w/ ventral horn
147
Subcortical nuclei of the cerebrum basal nuclei
3 nuclei:
Caudate nucleus, putamon, globus pallidus
Caudate nucleus + putamen= striatum
148
Main processing nuclei
. Receive info from various regions, cluster of neuron cell bodies in CNS
149
Globus pallidas
Main efferent path, excites or inhibits movements
- internal and external segment
150
Ganglia
Cluster of neuron cell bodies in the PNS
151
Types of transmembrane protein involved in generating AP
Voltage gated sodium,voltage gated potassium, sodium-potassium pump
152
Types of gated channels
Voltage-gated, ligand-gated,mechanically gated channels
- leakage channels are always open
153
Simple steps of AP
Depolarization, depolarization, hyper polarization
- occur do to opening and closing of voltage gated Lon channels
154
When do active gates open?
Open in response to depolarization
155
Saltatory conduction
Rapid transmission of AP along myelinated axons, where the impulse jumps from 1 node of ranvier to the next
156
Threshold
Membrane potential at which an AP is trigged
157
Basic parts of a chemical synapse
Presynaptic terminal, synaptic cleft, and post synaptic membrane
- they function to transmit signals via neurotransmitters
158
Types of spina bifida
Occult, meningocele, myclomeningocele
159
Major subcortical nuclei
Basal nuclei which are involved n movement regulation
160
Direct pathway of basal nuclei and indnect
Direct: encourage movement, indirect: discourages it
161
Major neurotransmitters of basal nuclei
Dopamine, GABA, glutamate
162
Major regions of diencepharon
Thalamus, hypothalamus,and epithalamus
163
Function of cerebellum
Coordinates movement and balance
164
Function of cerebella peduncle
Transmits specific types of info,
165
Major arteries of function of circle of Willis
Internal carotid and basilar artery
- provides collateral blood flow to brain
166
Major venous return vessels
Include internal jugular veins
167
What is arachnoid villi associated w/?
Return of CSF to venous system
