Lecture - Exam 2 Flashcards
1
Q
how are the cells in nervous tissue organized
A
cells are densely packed and intertwined
2
Q
what are the 2 main cell types in nervous tissue
A
neurons and support cells
3
Q
what are neurons
A
they transmit electrical signals, they are excitable
4
Q
what are support cells
A
non-excitable, surround and wrap neurons
5
Q
what cell conducts an action potential
A
neurons
6
Q
how do neurons conduct action potentials
A
when neurons conduct electrical impulses along their plasma membrane
7
Q
describe the longevity of neurons
A
they can live and function for a lifetime
8
Q
describe how often neurons divide
A
they do not divide - fetal neurons lose their ability to undergo mitosis except for neural stem cells in the hippocampus and olfactory bulbs
9
Q
describe the metabolic rate in neurons
A
they have a high metabolic rate, they require abundant oxygen and glucose
10
Q
what do neurons form to communicate
A
synapses (sites a communication between cells)
11
Q
what is the shape of the neuron cell body
A
perikaryon or soma
12
Q
in addition to normal organelles, what else to neurons contain
A
nissl bodies/ nissl substance
13
Q
what are nissl bodies made of
A
densely packed, flattened sacs of rough ER and free ribosomes
14
Q
what do nissl bodies do
A
renew membranes of the cell/make proteins (membrane processes extend from cell body)
15
Q
what are the 2 neuron membrane processes
A
dendrites and axons
16
Q
what do dendrites look like
A
they extensively branch from the cell body
17
Q
what do dendrites do
A
transmit electrical signal TOWARD the cell body because they act as receptive sites
18
Q
what many axons does each neuron have
A
one
19
Q
what is the function of axons
A
produce and conduct action potentials by transmitting impulses AWAY from the cell body
20
Q
what 3 components are axons made of
A
neurofilaments, actin microfilaments, and microtubules
21
Q
what is the role of neurofilaments, actin microfilaments, and microtubules in axons
A
provide strength along the length of axon and axonal transport - aid in the transport of substances to and from the cell body
22
Q
what is the axon hillock
A
the initial segment of the axon that initiates action potentions
23
Q
what are terminal branches
A
multiple branches at the end of axons
24
Q
what are axon terminals (aka end bulbs or terminal boutons)
A
knobs at the end of branches
25
what are the 3 structural classes of neurons
multipolar, bipolar, and unipolar
26
what is multipolar neurons
more than 2 processes, usually many dendrites and one axon (99% of all neurons)
27
what is bipolar neurons
only 2 processes that extend from opposite sides of cell body
28
what is unipolar neurons
only one process that emerges from cell body and divides like an inverted letter T
29
what are the 2 types of processes in unipolar neurons
peripheral process and central process
30
in synapses, how many directions do signals pass
just 1 direction
31
what are neurotransmitters
chemical messengers
32
what is a presynaptic neuron
conducts signal TOWARD a synapse
33
what is a postsynaptic neuron
transmit electrical activity AWAY from a synapse
34
what do postsynaptic neurons have in their membranes that presynaptic neurons do not
receptors for neurotransmitters
35
what are synaptic vesicles
membrane bound sacs containing neurotransmitters
36
where are synaptic vesicles found
present in axon termins on presynaptic side
37
what is the synaptic cleft
it separates the plasma membrane of the 2 neurons
38
how does a neurotransmitter get from one neuron cell to the next
it is released into the synaptic cleft, diffuses to second neuron, then binds to receptors on membrane of second neuron
39
what are neuroglia cells
supporting cells in the CNS
40
what is the structure of neuroglia cells
have branched processes and a central cell body
41
what is the population of neuroglia cells compared to neurons and other cells in the brain
outnumber neurons 10 to 1 and make up half the mass of the brain
42
how many types of supporting cells are in the CNS vs PNS
CNS - 4 types of neuroglia cells
PNS - 2 types of supporting cells
43
What are the 4 types of supporting cells in the CNS
astrocytes, microglia, ependymal cells, and oligodendrocytes
44
what is the most abundant glial cell type
astrocytes
45
what are the main functions of astrocytes (6)
1. take up/release ions to control environment around neurons
2. recapture and recycle neurotransmitters
3. involved with synapse formation in developing neural tissue
4. produce molecules necessary for neural growth
5. involved in memory (degradation leads to alzheimers)
6. maintain blood-brain barrier
46
what is the least abundant supporting cell in the CNS
microglia
47
what is the main function of microglia
defense - engulf invading microorganisms and dead neurons (act as macrophages of the CNS)
48
what are microglia derived from
blood cells called monocytes
49
what is the main function of ependymal cells
help produce CSF
50
where are ependymal cells mainly found and why
line the brain ventricles and central cavity of the spinal cord to help circulate the CSF
51
what special feature is apart of ependymal cells
cilia which helps circulate CSF
52
what is the main function of oligodendrocytes
they wrap their cell processes (few) around axons and produce myelin sheaths
53
what are the 2 supporting cells in the PNS
satellite cells and schwann cells
54
where are satellite cells found
surround sensory neuron cell bodies within ganglia of PNS
55
where are schwann cells found
surround axons in the PNS
56
what do schwann cells form around axons in the PNS
myelin sheaths
57
what are myelin sheaths
segmented structures composed of the lipoprotein myelin
58
what are the functions of myelin sheaths (2)
form and insulating layer to prevent leakage of electrical current AND increases the speed of impulse conduction (50X)
59
what is multiple sclerosis (MS) and what are the symptoms
an autoimmune disease that results from degeneration of myelin leading to weakness, difficulty walking, and vision disturbances
60
when are myelin sheaths in the PNS formed
develop during fetal period and in the first year of postnatal life
61
what is the nodes of ranvier
gaps between myelin segments along axon
62
how do schwann cells form around the axon
they wrap in concentric layers around the axon to cover is in a tightly packed coil of membranes
63
how many myelin sheaths can form in one schwann cell
one; one schwann cell=one myelin sheath
64
which axons are myelinated and which are not
thick axons are myelinated and thin axons are unmyelinated
65
how are unmyelinated axons different than myelinated axons
conduct electrical signals more slowly
66
where are the unmyelinated cells
certain visceral sensory neurons that conduct temperature and pain
67
do schwann cells still support unmyelinated cells
yes, they just don't for sheaths
68
what support cells form myelin sheaths in the CNS
oligodendrocytes
69
how many axons does one oligodendrocyte coil around
several
70
what is gray matter in nerve tissue in CNS
cell bodies (neurons, glial cells), dendrites, and axon terminals
71
what is white matter in nerve tissue in CNS
myelinated axons
72
where is gray matter found and in what formation (4)
nuclei- clusters of neuron cell bodies in CNS
ganglia- clusters of neuron cell bodies in PNS
columns- rows of neuron cell bodies
cortex- continuous sheet (only cerebrum and cerebellum)
73
where is white matter
tracts (only in CNS)
74
what are the 2 divisions of the nervous system
central nervous system (CNS) and peripheral nervous system (PNS)
75
what are the 2 parts of the CNS
brain and spinal cord (integration and command center)
76
what does rostral mean
only for CNS, toward the nose
77
what does caudal mean
only for CNS, toward the tail
78
where is the PNS
everything outside of the CNS, nerves extending from the brain and spinal cord
79
what are the 2 types of nerves in the PNS
cranial nerves and spinal nerves
80
what are the three main classes of neurons
afferent neurons, efferent neurons, and interneurons
81
what are afferent neurons
sensory neurons that sends info toward the CNS
82
where are afferent neurons
cell bodies outside the CNS in sensory ganglia, central processes grow into CNS
83
what are efferent neurons
motor neurons that send into away from CNS
84
where are efferent neurons
cell bodies in CNS, axons leave CNS and enter PNS
85
what and where are interneurons
located totally within CNS, in synapse with sensory neurons
86
where is the somatic body region
outside of the ventral body cavity
87
where is the visceral body region
inside of the ventral body cavity and glands (glans are outside of ventral cavity)
88
what 4 subdivisions do the body regions result in
somatic sensory, visceral sensory, somatic motor, and visceral motor
89
what is the modality of somatic sensory
something sensed
90
where are general somatic senses
receptors are widely spread over body wall
91
what are the general somatic senses
touch, pain, vibration, pressure, and temperature
92
what are proprioceptive senses
detect stretch in tendons and muscle
93
what is body sense
position and movement of body in space
94
where are special somatic senses
receptors are restricted to head
95
what are special somatic senses
hearing, vision, smell, and equilibrium (balace)
96
how many modalities does visceral sensory have
7
97
what are general visceral senses
stretch, pain, temperature, chemical changes, nausea, and hunger
98
where are general visceral senses mainly felt
digestive, urinary tract, and reproductive organs
99
what are special visceral senses
taste
100
what does the general somatic motor system do
signal contraction of skeletal muscles
101
is the somatic motor system controlled voluntarily or does it just happen
under voluntary control
102
what is the visceral motor system
regulates the contraction of smooth and cardiac muscle, secretion by glands, and adipose (fat)
103
what system does the visceral motor system make up
the autonomic nervous system
104
what are the nicknames for the somatic motor system and visceral motor system
voluntary nervous system and involuntary nervous system
105
what are nerves
cordlike organs in the peripheral nervous system
106
what are nerves made of
numerous axons wrapped in connective tissue
107
what are nerve fascicles
groups of axons bound into bundles
108
what are the 3 types of nerve fascicles
endoneurium, perineurium, and epineurium
109
what is the endoneurium
a layer of delicate loose connective tissue surrounding each axon
110
what is the perineurium
dense irregular connective tissue wrapping surrounding a nerve fascicle
111
what is the epineurium
the whole nerve is surrounded by tough fibrous sheath, dense irregular connective tissue
112
when does the nervous system develop in embryonic development
by week 4
113
what is developed in the nervous system in embryonic development
embryonic neural tube and neural crest cells
114
what cells are the neural tube wall made of
neuroepithelial cells
115
what do the neuroepithelial cells become
they divide and become neuroblasts
116
what are neuroblasts
immature neurons
117
where is white and gray matter organized
gray matter is centrally located and white matter is externally located
118
what is the extra layer of amtter in some brain regions
theres an addition layer of gray matter external to white matter in SOME brain regions
119
why is there an extra layer of gray matter sometimes
due to groups of neurons migrating externally
120
what are cortexes
outer layer of gray matter
121
where are cortexes located
in cerebrum and cerebellum
122
what do neuroblasts cluster into in embryonic development
they cluster into dorsal (alar) plates and ventral (basal plates)
123
what do alar plate cells become
interneurons of CNS (somatic sensory and visceral sensory interneuron cell bodies)
124
what do basal plate cells become
motor neurons (visceral motor and somatic motor neuron cell bodies)
125
what do sensory neurons come from
form from neural crest cells of embryo
126
what does the brain arise from in ED
the rostral (anterior) part of the neural tube
127
what does the hollow part of the neural tube become in ED
the central cavity of brain (ventricles) and central cavity of spinal cord
128
what are the 3 primary brain vesicles in 4 week embryo
prosencephalon (the forebrain)
mesencephalon (the midbrain)
rhombencephalon (the hindbrain)
129
what secondary vesicles does the prosencephalon form
telencephalon and diencephalon
130
what secondary vesicles does the mesencephalon form
none (remains undivided)
131
what secondary vesicles does the rhombencephalon form
metencephalon and myelencephalon
132
what structure of the adult brain is derived from the telencephalon
the cerebral hemispheres
133
what structure of the adult brain is derived from the diencephalon
thalamus, hypothalamus, and epithalamus (includes pineal gland)
134
what structure of the adult brain is derived from the mesencephalon
midbrain
135
what structure of the adult brain is derived from the metencephalon
pons and cerebellum
136
what structure of the adult brain is derived from the myelencephalon
medulla oblongata
137
in ED what do the cerebral hemispheres envelop
the diencephalon and midbrain
138
what makes up the brain stem
the midbrain, pons, and medulla oblongata
139
what happens to the shape of the cerebral hemispheres in ED
wrinkling due to more neurons fitting within limited spaces
140
what are meninges
fibrous membranes that cover the brain and spinal cord
141
what are the general functions of meninges
cover and protect the CNS, enclose and protect vessels that supply the CNS, contain cerebrospinal fluid
142
what are the 3 layers in the meninges
dura mater, arachnoid mater, and pia mater
143
which is the strongest layer
the dura mater
144
what type of tissue is the dura mater made of
dense irregular connective tissue
145
what 2 layers are the dura mater made of
periosteal layer (against skull) and meningeal layer
146
what parts of the 2 layers of the dura mater are not fused
fused except to enclose the dural sinuses (blood filled spaces)
147
what is the largest dural sinus
the superior sagittal sinus
148
what are falxes
dura mater that subdivides the cranial cavity
149
what is the only layer of dura mater that covers the spinal cord
only the meningeal layer (no periosteal layer)
150
what is the epidural space
near the spine, there is a space between the bones and the dural layer. this is called the epidural space
151
what is the epidural space filled with
adipose and blood vessels
152
what membrane is beneath the dura mater
the arachnoid mater
153
what is the subdural space
the potential space between the dura and arachnoid mater (not in healthy brain)
154
what is the subarachnoid space filled with
filled with CSF, contains blood vessels that supply the brain
155
what is the subarachnoid space
the true space between the arachnoid and pia mater
156
what is arachnoid villi
areas where arachnoid mater grow through the dura mater where blood sinuses are
157
what does the arachnoid villi do
allow CSF to pass into the dural blood sinuses, acts as a faucet to allow CSF to move out of sinuses
158
what is the pia mater made of
delicate loose connective tissue
159
where is the pia mater found
it clings tightly to the surface of the brain (follows all convolutions of the cortex over gyri and into sulci)
160
what are the ventricles of the brain
expansion of brains central cavity that is filled with CSF (extracellular fluid of central nervous system)
161
what cell are the ventricles lined with
ependymal cells
162
what are all ventricles continuous with (2)
all ventricles continuous with each other and continuous with the central canal of the spinal cord
163
what are the 4 main ventricles of the brain
lateral V, third V, cerebral aqueduct, and fourth V
164
what are the 2 parts of the lateral ventricles
2 hemispheres, the first and second ventricles
165
what is the shape of the lateral ventricles
horseshoe shaped (ram horns) from bending of the cerebral hemispheres
166
where is the third ventricle
lies in the diencephalon
167
what connects the third ventricles to both the lateral ventricles
the interventricular foramen
168
where is the cerebral aqueduct
lies in the midbrain
169
what is the purpose of the cerebral aqueduct
connects the third and fourth ventricles
170
where is the fourth ventricle
lies in pons and medulla oblongata
171
what does the fourth ventricle connect to
connects to the central canal of the spinal cord
172
what is the forth ventricle continuous with and what connects them
the subarachnoid space via median and 2 lateral apertures
173
what is the purpose of cerebrospinal fluid (CSF) (3)
provides a liquid cushion for the brain and spinal cord, filtrates blood, and removes waste
174
where is the CSF formed
in choroid plexuses in the brain ventricles
175
how is the CSF returned to blood and what what pace
returned in dural sinuses through arachnoid villi (500 ml/day)
176
what are choroid plexuses
highly folded, capillary rich membranes
177
what cells are closed associated (always near) choroid plexuses
ependymal cells
178
what is the main protection for the brain
the blood brain barrier
179
what does the blood brain barrier prevent
prevents most blood borne toxins from entering the brain
180
what in the blood brain barrier prevents things from entering the brain
impermeable capillaries
181
what CAN pass through the blood brain barrier
nutrients (oxygen), alcohol, nicotine, anesthetics, and tight junctions
182
what are the tight junctions in the blood brain barrier between
between endothelial cells in brain capillaries
183
what is the exchange dependent on in the tight junctions in the BB barrier
dependent on transport through capillary cells (not between cells)
184
can anything pass through the tight junctions in the BB barrier and why
no, it is selective because the cells have specific transport proteins
185
what is in the central column of gray matter in spinal pathways
dorsal and ventral horns that form an H shape
186
what is in the lateral white matter in spinal pathways
made of myelinated and unmyelinated axons that run on tracts
187
what are the two types of tracts in white matter
ascending and descending
188
what are ascending tracts in white matter
sensory pathways, dorsal tracts
189
what are descending tracts in white matter
motor pathways, ventral tracts
190
what are projection axons (fibers)
what axons are called in tracts in white matter of spinal pathways
191
in ascending pathways, how many neurons are typically in a series
2 or 3
192
what are 1st order neurons in ascending pathways
sensory neurons
193
what are 2nd order neurons in ascending pathways
interneurons in CNS
194
what are 3rd order neurons in ascending pathways
interneurons in thalamus to cerebral cortex
195
how are the pathways on each hemisphere related
they are paired, one on each side of the body
196
what is decussation
most ascending pathways cross over
197
what is the contralateral side of ascending pathways
information from one side crosses over to the other side
198
what is the ipsilateral side of ascending pathways
the pathway remains on the same side, no crossing over
199
what are the 3 primary ascending pathways
dorsal column pathway, spinothalmic pathway, and spinocerebellar pathway
200
how many neurons are in dorsal column pathways
2 neurons in series
201
what sense are involved with the dorsal column pathways
touch, pressure, conscious proprioception, and discriminative (fine detail) sense
202
where are dorsal column pathways mainly
they run in dorsal columns (tracts); fasciculus gracilis (axons enter from lower body) and fasciculus cuneatus (upper body)
203
what do 1st order neurons do in dorsal column pathways
enter spinal cord and ascend to medulla (no synapse until medulla oblongata)
204
what do 2nd order neurons do in dorsal column pathways
synapse with 2nd order neurons in medulla, decussate and travel to thalamus
205
what do 3rd order neurons do in dorsal column pathways
from thalamus to primary somatosensory area of cerebral cortex, processed to consciousness
206
how many neurons are in spinothalmic pathways
3
207
what senses are involved with spinothalmic pathways
pain, temperature, non-discriminative touch
208
what do 1st order neurons do in spinothalmic pathways
synapse with 2nd order neurons immediately in dorsal horns of gray matter in spinal cord
209
what do 2nd order neurons do in spinothalmic pathways
immediately decussate in spinal cord and ascend to thalamus
210
what do 3rd order neurons do in spinothalmic pathways
2nd order neurons synapse with 3rd order neurons in thalamus to primary somatosensory area of cerebral cortex
211
how many neurons are in spinocerebellar pathways
2
212
what sense is involved with spinocerebellar pathways
proprioception to cerebellum (unconscious), cerebellum modifies body movements and knows the positions of body parts
213
what do the 2 neurons do in spinocerebellar pathways
1st order neurons synapse with 2nd order neurons in dorsal horns (gray matter) of spinal cord, run in spinocerebellar tracts through pons to cerebellum
214
do spinocerebellar pathways take part in decussation
either no decussation or cross back to same side on pons or cerebellum (ipsilateral info)
215
what are descending pathways responsible for
deliver motor instructions from the brain to the spinal cord (motor neurons)
216
what are the 2 groups of descending pathways
corticospinal (pyramidal) tracts and other motor pathways (extrapyramidal)
217
what is corticospinal (pyramidal) pathways responsible for
precise and skilled voluntary movement
218
where do neurons originate in corticospinal (pyramidal) pathways
in primary motor areas of cerebral cortex
219
where is the synapse in corticospinal (pyramidal) pathways
directly on somatic motor neurons in ventral horns of gray matter in cord OR on short interneurons near motor neurons
220
where do neurons decussate in corticospinal (pyramidal) pathways
in medulla (pyramids) as they descend but some decussate in spinal cord near somatic mortor neuron cell bodies
221
what are other descending (extrapyramidal) pathways responsible for
unconscious, course, and postural movements
222
where do other descending (extrapyramidal) pathways originate
in midbrain and pons (not cerebral hemispheres)
223
where do other descending (extrapyramidal) pathways decussate
in the pons
224
what accounts for the majority (80%) of brain mass
the cerebral hemispheres
225
what divides the cerebrum into lobes
deep sulci
226
what is the central sulcus
it separates the frontal and parietal lobes
227
what 2 gyri is the central sulcus bordered by
precentral gyrus and postcentral gyrus
228
what does cortex gray matter allow us to do
be aware of ourselves, communicate, remember, understand, initiate and control voluntary movements, and sensory perception
229
what are the 4 main areas of Brodmann areas that you need to know
(1-3) primary somatosensory, (5,7) sensory association, (4) primary motor, and (6) pre-motor... basically mostor areas, sensory areas, and 2 association areas
230
what are the 2 types of association areas
association axons and commissural axons
231
what are association axons (fibers)
communications between different areas on same hemisphere
232
what are commissural axons
communication between different hemispheres
233
where is the primary motor cortex (motor area)
precentral gyrus (Brodmann area #4)
234
what are the main types of cells in the the primary motor cortex
pyramidal cells
235
what are pyramidal cells
large neurons of primary motor cortex
236
where do the axons of pyramidal cells go in the primary motor cortex
axons descend in corticospinal (pyramidal) tracts through brainstem and spinal cord to control skilled movement
237
what is a motor homunculus
a body map of the motor cortex
238
what is somatotopy
body is represented spatially in many parts of the CNS; neurons to different body regions remain separated in CNS
239
where is the premotor cortex (motor area)
anterior to the motor cortex (Brodmann's #6)
240
what does the premotor cortex control
voluntary actions dependent on sensory feedback (ex. following verbal instructions, catching a ball, etc.) and planning movements
241
where is the primary somatosensory cortex (sensory areas)
along the postcentral gyrus (corresponds with Brodmann areas #1-3)
242
what is the primary somatosensory cortex involved with
conscious awareness of general somatic sense (touch, pressure, pain, and temp)
243
what is spacial discrimination
precisely locates a stimulus (primary somatosensory cortex)
244
what are sensory association areas
cortical areas involved in conscious awareness and context of sensation
245
where are the sensory association areas located and what sense is corresponded to each (4)
parietal lobes (general somatic sense)
temporal lobes (auditory)
occipital lobes (vision)
insula (taste)
246
where are somatosensory association areas
posterior to the primary somatosensory cortex (Brodmann's #5 and 7)
247
what is the somatosensory association areas responsible for
integrate sensory inputs (touch, pressure, and others) and draws upon stored memories of past sensory experiences
248
what is basal nuclei (ganglia)
group of gray matter nuclei deep within the cerebral white matter
249
what makes up the corpus striatum
caudate nucleus (arches over thalamus), lentiform nucleus (lens shaped), and claustrum
250
what are the 2 parts of lentiform nucleus
globus pallidus and putamen
251
what are the functions of basal nuclei
cooperate with the cerebral cortex in controlling movements, receive input from many cortical areas, start stop and regulate intensity of voluntary movements, estimate passage of time
252
what is the limbic system known as
the emotional brain
253
where is the limbic system
medial aspect of cerebral hemisphere and within the diencephalon (hypothalamus)
254
what is the limbic system composed of
septal nuclei, cingulate gyrus, hippocampal formation, and part of the amygdala
255
what shape does the limbic system form
a ring structure
256
what are septal nuclei in the limbic system responsible for
the pleasure region and sexual responses
257
what is the cingulate gyrus in the limbic system responsible for
emotional responses to stimuli, including specific behaviors
258
what is the amygdala in the limbic system responsible for
the fear center (including fearful memories), coordinate sympathetic responses to fear
259
what is the hippocampal formation in the limbic system responsible for
(hippocampus and parahippocampal gyrus) involved with long term memory and spatial memory
260
what is in the center of the forebrain
the diencephalon
261
what are the 3 structures composing the diencephalon
thalamus, hypothalamus, and epithalamus
262
what does the diencephalon border
the third ventricle
263
what type of matter is the diencephalon made of
gray matter
264
what makes up most of the diencephalon
the thalamus
265
what do the nuclei in the thalamus do
act as relay stations for incoming sensory messages, the gateway to the cerebral cortex
266
what do sensory axons do in the thalamus
All sensory axons to cerebral cortex synapse in at
least one of its nuclei
267
what is the one exception to sensory axons passing through the thalamus
olfaction to limbic system bypasses thalamus
268
what do the nuclei in the thalamus do to sensory signal
either amplify or tone down
269
what are the 2 types of thalamic nuclei
lateral geniculate nucleus and medial geniculate nucleus
270
what do lateral geniculate nuclei do in the thalamus
receive input from axons in optic nerves coming from retina and relay signals via optic tracts to primary visual centers in occipital lobe of cerebral hemispheres
271
what do medial geniculate nuclei do in the thalamus
relay auditory information to cerebral hemispheres
272
what is the main role of the hypothalamus
it is the main visceral control center of the body
273
what are the 5 visceral functions of the hypothalamus
control of the autonomic nervous system, Regulation of body temperature, Regulation of hunger and thirst sensations, Controls secretion of pituitary gland hormones, and Control of emotional responses by organizing limbic input
274
where does the epithalamus receive input from
the retina of eye
275
what structure is included in the epithalamus
the pineal body
276
what are the main functions of the pineal body
secrete the hormone melatonin, circadian rhythms, light/dark cycles
277
what makes up the brain stem
the pons and medulla
278
what nuclei are in the midbrain
nuclei of cranial nerve III and IV (eye movement)
279
where are the cerebral peduncles on the midbrain
located on the ventral surface of midbrain
280
what does the cerebral peduncle contain
pyramidal tracts, red nucleus, and substantia nigra
281
where are the colliculi on the midbrain
inferior and superior on the dorsal surface
282
where are the superior cerebellar peduncles on the midbrain
on dorsal surface, connects the midbrain to the cerebellum
283
what surrounds the cerebral aqueduct in the midbrain
periaqueductal gray matter
284
what are the 3 main functions of periaqueductal gray matter in the midbrain
Fight-and-flight reaction; panic behaviors (together with amygdala), Mediates response to visceral pain (cold sweat, etc.), Analgesia
285
what do the nuclei in the superior colliculi do
contains nuclei that act in
visual reflexes; involuntary eye tracking of objects
286
what do the nuclei in the inferior colliculi do
nuclei that act in reflexive responses to sound
287
what are the 2 nuclei in the midbrain
substantia nigra and red nucleus
288
what is the substantia nigra responsible for
Functionally linked to the basal nuclei
289
what is the red nucleus responsible for
Minor motor control and course movements of limbs
290
where are the pons
between the midbrain and medulla oblongata
291
what axons are in the pons
axons of pyramidal tract
292
what nuclei are in the pons
nuclei of cranial nerves V, VI, and VII
293
where are pontine nuclei and what is their function
the pons and they are relay nuclei to cerebellum
294
what is the input and output of pontine nuclei
Input from somatic motor cortex (Brodmann’s 4), Output to cerebellum: fine tune motor control coming
from cortex
295
what is the most caudal level of the brain stem
the medulla oblongata
296
what are the main parts of the medulla oblongata
pyramids, olives, nuclei of cranial nerves VIII-XII, and vestibular nuclei
297
what nucleus is in the olives
inferior olivary nucleus
298
what are the olives responsible for
Relay of sensory information to cerebellum; info
needed to coordinate movements
299
what is the vestibular nuclei responsible for
Relay from vestibular apparatus in inner ear to
cerebellum, Relay info about equilibrium (balance)
300
where is the reticular formation
the core of the medulla, pons, and midbrain
301
what are the 3 columns of gray matter in the reticular formation
Midline raphe nuclei, Medial nuclear group, and Lateral nuclear group
302
what are the 4 visceral centers of reticular formation
cardiac center -> heart rate
vasomotor center -> control blood pressure
medullary respiratory center
centers for hiccuping, sneezing, swallowing, and
coughing
303
what is the reticular activating system responsible for
Maintains consciousness and alertness and Functions in sleep and arousal from sleep
304
what is the cerebellum responsible for
Smoothes and coordinates body movements, Helps maintain equilibrium, and “Motor memory”
305
what are the ridges called on the cerebeullum
folia
306
what are the 3 main regions in the cerebellum
cortex (gray matter), internal white matter, and deep cerebellar nuclei (gray matter)
307
what does the deep cerebellar nuclei do in the cerebellum
relay to primary somatic motor cortex
(output from cerebellum)
308
what information does the cerebellum receive
On equilibrium (balance), On current movements of limbs, neck, and trunk, and From the cerebral cortex (motor control signals)
309
what info does the cerebellum output
Cerebellum informs primary motor cortex of corrections
to motor patterns to smooth out movement and
maintain balance
310
what do purkinje cells (neurons) of cerebellum cortex do
Integrate all sensory input and coordinate output and Information TO primary motor cortex via deep cerebellar nuclei
311
what is the role of the 3 cerebellar peduncles
Thick tracts connecting the cerebellum to the brain stem
312
what does the superior cerebellar peduncles do
(midbrain) Carry axons FROM cerebellum to primary motor cortex via deep cerebellar nuclei
313
what does the middle cerebellar peduncles do
(pons) Primary motor cortex TO cerebellum via pontine nuclei
314
what do the inferior cerebellar peduncles do
(medulla oblongata) Proprioception input TO cerebellum and Equilibrium/balance input from inner ear via vestibular nuclei in medulla TO cerebellum
315
what is the peripheral nervous system (PNS)
nervous structures outside the bran and spinal cord including cranial nerves and spinal nerves
316
what are the functional components of the PNS
sensory inputs (somatic and visceral) and motor outputs (somatic motor system and visceral motor system)
317
how do the spinal nerves connect to the spinal cord
by a dorsal root and a ventral root
318
what type of neurons are in the dorsal root
sensory neurons
319
where are the cell bodies of the dorsal root
located in the dorsal root
ganglion
320
what type of neurons are in the ventral root
motor neurons arising from gray column
321
what do the spinal nerves branch into
dorsal and ventral ramus
322
which structures are mixed nerves in the PNS
spinal nerves and dorsal & ventral rami (have both sensory and motor neurons)
323
what does the dorsal rami innervate
a horizontal strip of skeletal muscle and skin on dorsal side of axial region (back, back of neck and head)
324
what does the ventral rami innervate
anterior thorax, anterior
abdomen, and limbs
325
what does the ventral rami lead branch off
lateral and anterior cutaneous branches
326
what is dermatome
an area of skin innervated by
spinal nerves
327
what is the trunk innervated by
by cutaneous branches of
different spinal nerves
328
what are the upper limbs innervated by
by nerves of the brachial plexus
329
what is the anterior surface of the lower limbs innervated by
lumbar nerves
330
what is the posterior surface and butt of the lower limbs innervated by
sacral nerves
331
what are peripheral sensory receptors
Structures that pick up sensory stimuli from inside and outside of body
332
what do peripheral sensory receptors do
Initiate electrical signals in sensory neuron axons
333
what are the 3 types of peripheral sensory receptors
exteroceptors, interoceptors, and proprioceptors
334
what are exteroceptors
sensitive to stimuli arising from outside the body
335
where are exteroceptors
at or near body surfaces
336
what senses do exteroceptors respond to
touch, pressure, pain, and temp
337
what are interoceptors
receive stimuli from internal viscera
338
what are proprioceptors
monitor degree of stretch
339
where are proprioceptors
Located in musculoskeletal organs
340
what are the 2 things the 3 sensory receptors exist as
nerve endings of sensory neurons OR receptor cells
341
what are receptor cells
specialized epithelial cells or small neurons; these synapse with sensory neurons (usually with special senses)
342
what are the 2 groups of receptors as nerve ending
free nerve endings and encapsulated nerve endings
343
what do nerve endings of sensory neurons monitor
touch, pressure, vibration, proprioception, pain, and temp
344
where are free nerve endings
Abundant in epithelia and underlying connective tissue, however, widely distributed
345
what do free nerve endings respond to
pain and temp
346
what are hair follicle receptors
they wrap around hair follicles and are a specialized type of free nerve endings
347
what do encapsulated nerve endings consist of
one or more ends of sensory neurons
348
where are encapsulated nerve endings
Enclosed in connective tissue and support cells
349
what are 2 examples of encapsulated nerve endings
meissner's corpuscle and pacinian corpuscle
350
what is meissner's corpuscles
Spiraling nerve ending surrounded by Schwann cells and connective tissue; DISCRIMINATIVE TOUCH
351
where does meissener's corpuscles occur
in the dermal papillae (skin), Abundant in sensitive, hairless areas of the skin
352
what is pacinian corpuscles
Single nerve ending surrounded by layers of flattened Schwann cells/connective tissue (onion-like)
353
where does pacinian corpuscles occur
in the deep dermis (skin) and hypodermis
354
what is pacinian corpuscles sensitive to
deep pressure/vibration
355
what do proprioceptors do
Monitor stretch in locomotory organs
356
what are the 3 types of proprioceptors
Muscle spindles, Golgi tendon organs, Joint receptors
357
what do muscle spindles do
measure the changing length of a muscle
358
where are muscle spindles
Imbedded in the perimysium between muscle fascicles (about 50 spindles/muscle)
359
what type of fibers make muscle spindles
intrafusal fibers (specialized skeletal muscle cells)
360
what wraps around intrafusal fibers in muscle spindles
2 types of sensory nerve endings
361
where are golgi tendon organs located
near muscle-tendon junction
362
what do golgi tendon organs do
monitor tensions within tendons and prevent over contraction of muscle
363
what are joint receptors
mainly synovial joints with sensory nerve endings within the joint capsules
364
what do joint receptors do
monitor joint position
365
what are receptor cells
Specialized cells; either modified epithelial cells or modified neurons
366
where do recepetor cells synapse
synapse with sensory neurons
367
what are 3 examples of receptor cells
photoreceptors, taste receptors, and hair cells
368
what do somatic motor neurons do
control skeletal muscle cells
369
what are somatic motor neurons
large, myelinated axons
370
where are the cell bodies of somatic motor neurons
in brainstem and ventral gray matter of spinal cord
371
where do somatic motor neurons exit from motor areas of the brain
exit via cranial nerves and through ventral root into spinal nerves
372
what is a motor unit
one motor neuron and all the muscle cells it innervates
373
how manny skeletal muscle cells are innervated by one motor neuron
multiple (several terminal branches of axon, each branch innervates a different skeletal muscle cell)
374
what is a nerve plexus
a network of nerves
375
where are the ventral rami nerve plexuses
in cervical, brachial, lumbar, and sacral regions
376
what do the ventral rami nerve plexuses serve
primarily the limbs
377
what is the order of the brachial plexus (C5-T1) (ex)
rami -> trunks -> divisions -> cords -> branches
378
what is the autonomic nervous system
a system of visceral motor neurons (controls most visceral organs)
379
what does the ANS innervate
smooth muscle, cardiac muscle, adipose tissue, and glands
380
what visceral functions does the ANS regulate
Heart rate, blood pressure, digestion, urination
381
what are the 2 divisions of the ANS
sympathetic and parasympathetic divisions
382
do the sympathetic and parasympathetic divisions innervate the same or different structures
the same structures but causes opposite effects
383
what is the sympathetic system
activated during exercise, excitement, and emergencies (fight or flight)
384
what is the parasympathetic system
concerned with conserving energy (rest and digest)
385
what are the 2 motor neuron chains that make up the ANS
preganglionic neuron and postganglionic neuron
386
where do the 2 motor neuron chains of the ANS synapse
in ganglia
387
where are the preganglionic neurons
cell bodies are in the CNS
388
where are the postganglionic neurons
cell bodies are in ganglia, axons to target cells
389
are the postganglionic neurons of the autonomic system myelinated or nonmyelinated
nonmyelinated
390
what is the main difference between the sympathetic and parasympathetic division
emerge from different regions of the CNS
391
where does the sympathetic division emerge from
from T1-L2 regions of spinal cord (also called the thoracolumbar division)
392
where does the parasympathetic division emerge from
emerge from 1) brain stem and 2) sacral region of spinal cord (also called the craniosacral division)
393
where are the 2 outflows of the parasympathetic division (PSD)
cranial outflow and sacral outflow
394
what does the cranial outflow of the PSD innervate
organs of the head, neck, thorax, and abdomen
395
what does the sacral outflow of the PSD innervate
remaining abdominal and pelvic organs
396
where do preganglionic fibers in the cranial outflow of the PSD run
oculomotor nerve (smooth muscle of eye), facial nerve (salivary glands, lacrimal glands), glossopharyngeal nerve (parotid salivary glands), and vagus nerve (many visceral organs in thorax and abdomen)
397
where do branches of the vagus nerve run
autonomic nerve plexuses (network of autonomic nerve)
398
where does sacral outflow of the PSD emerge from
S2-S4
399
what does sacral outflow of the PSD innervate
organs of the pelvis and lower abdomen
400
where are the preganglionic cell bodies from sacral outflow of the PSD located
in visceral motor region (lateral) of spinal gray matter
401
where are the axons from sacral outflow of the PSD located
axons run in ventral roots to ventral rami (branch from rami to form splanchnic nerves)
402
where does the sympathetic division emerge from
T1-L2
403
where are the preganglionic axons in the sympathetic division from
lateral gray horn (visceral motor) of spinal cord
404
what does the sympathetic division supply
visceral organs and strictures of superficial body regions (sweat glands, arrector pili, smooth muscle in eye)
405
does the parasympathetic or sympathetic division have more ganglia
parasympathetic
406
where is the sympathetic trunk ganglia located
on both sides of the vertebral column
407
what is the sympathetic trunk ganglia linked by
short nerves into sympathetic trunks
408
what are trunk ganglia joint to ventral rami by
by white and gray rami communicantes
409
what are white rami
preganglionic axons; myelinated
410
what are gray rami
postganglionic axons; non-myelinated
411
what is the general pattern of rami in sympathetic trunk ganglia
Ventral rami -> white rami to ganglion -> grey rami back to ventral rami -> branches to target cells/target organs
412
where are prevertebral ganglia
in abdomen and pelvis (lie anterior to vertebral column)
413
what is a special feature of prevertebral ganglia
they are unpaired, not segmentally arranged
414
when preganglionic neuron axons pass through trunk ganglia, what does it form
form splanchnic autonomic nerves to prevertebral ganglia
415
where are the main prevertebral ganglia
near autonomic plexuses
416
what is the sympathetic pathway to the head
preganglionic fibers start in spinal cord at T1-T4, fibers ascend in sympathetic trunk, synapse in superior cervical ganglion, postganglionic fibers associate with large arteries, carry to glands of head, smooth muscle in head, and vessels throughout the head
417
what is the sympathetic pathway to thoracic organs
Preganglionic axons originate at spinal levels T1-T6, Some axons synapse in nearest sympathetic trunk ganglion but some either ascend or descend to neighboring ganglia, Postganglionic axons run directly to the target organ supplied in autonomic nerves
418
what are the functions of the sympathetic pathway to thoracic organs
increase heart rate, dilate bronchioles, dilate blood vessels to the heart wall, inhibit the muscle and glands in the esophagus
419
what is the sympathetic pathway to abdominal organs
Preganglionic fibers originate in spinal cord T5-L2, pass through adjacent sympathetic trunk ganglia, travel in thoracic splanchnic nerves, Synapse in prevertebral ganglia on the abdominal aorta
420
what is the function of sympathetic pathways to abdominal organs
Inhibit activity of muscles and glands in visceral organs
421
what is the sympathetic pathway to pelvic organs
Preganglionic fibers originate in spinal cord T10–L2, some axons descend in chain into pelvis and synapse in sympathetic trunk ganglia but other preganglionic axons synapse in prevertebral ganglia, Postganglionic fibers proceed from plexuses to pelvic organs in splanchnic nerves
422
what constitutes the largest sympathetic ganglia
the adrenal medulla
423
what does the adrenal medulla secrete
epinephrine (adrenaline) into the blood
424
what stimulates the adrenal medulla to secrete epinephrine
preganglionic sympathetic fibers
