CNS Flashcards
1
Q
what types of cells allow for sensory input?
A
afferent cells
2
Q
what are efferent cells?
A
motor cells found in the CNS
3
Q
what cells innervate skeletal muscles and can only be excited by acetylcholine?
A
somatic efferent cells
4
Q
what cells innervates interneurons, are found in smooth and cardiac muscles and can be both excitatory or inhibitory?
A
autonomic efferent cells
5
Q
what does the cranial nerve innervate?
A
neck
shoulders
arms
hands
6
Q
how many cranial nerves do we have?
A
8 pairs
7
Q
what do the thoracic nerves innervate?
A
shoulders
chest
upper abdominal wall
8
Q
what do the lumbar nerves innervate?
A
lower abdominal wall
hips
legs
9
Q
what does the sacral nerve innervate?
A
genitals
lower digestive track
10
Q
how is the nervous system developped? (stages)
A
- fertilized egg
- ball of cell
- blastocyte week 1 begin to see a inner cell mass
- blastocyte week 2
- blastocyte week 3 formation of embryonic disk, neural plate
11
Q
at what stage does the neural tube begin to develop?
A
week 3
12
Q
explain the stages of neural tube development
A
- at week 3 the neural plate begins to form, separated as the ectoderm, mesoderm and endoderm
- midway through week 3 the ectoderm folds in creating a neural groove
- week 4 the neural groove is now the neural tube(CNS and part of PNS), the neural crest is a part of PNS, mesoderm becomes dura
- during week 4 vesicles begin to develop
13
Q
what are the neural tube vesicles that develop?
A
forebrain
midbrain
hindbrain
14
Q
what part of the CNS does the forebrain transition into?
A
-central hemisphere and thalamas
15
Q
what part of the CNS does the midbrain transition into?
A
midbrain
16
Q
what part of the CNS does the hindbrain transition into?
A
PONS
medulla
cerebellum
17
Q
what does the neural tube become in the CNS?
A
the spinal chord
18
Q
what does the neural tube cavity become in the CNS?
A
the ventricles and central canal
19
Q
what do the ventricles contain?
A
150 ml of CSF
20
Q
what produces the CNF?
A
choroid plexus
21
Q
which ventricles mostly produce the CNF?
A
2 lateral ventricles
22
Q
what are the 3 main fcts of the CNF?
A
supports and cushions the CNS
nourishment to the brain
absorbs metabolic waste
23
Q
what absorbs the metabolic waste?
A
arachnoid villi
24
Q
what is the CNF composition?
A
its a sterile, colorless fluid that contains glucose
25
how does the CNF circulate through the brain?
through passive diffusion
26
what space does the CSF enter?
subarachnoid space
27
what are the 2 types of hydrocephalus?
communicating
| non communicating
28
what is hydrocephalus?
accumulation of CSF in one ventricle
29
what are the 3 meningeal layer
dura mater
arachnoid membrane
pia matter
30
what is the space between arachnoid matter and pia matter
subarachnoid space
31
what do meninges cover?
cover the brain and spinal cord
32
how does the CSF return to the blood
at the dural sinus
33
what is the only substrate used to metabolize in the brain?
glucose
34
is their alot of glycogen in the brain?
no, glucose is not stored in the brain
35
what does the brain need a continuous supply of?
glucose and oxygen
36
is glucose transport to de brain dependent on insulin?
no
37
what can a few seconds of loss of blood supply to the brain cause?
loss of consciousness
38
what can a few minutes of loss of blood supply to the brain cause?
stoke
39
how does the blood travel to the brain
from the hear > common cartoid artery > vertebral a. > internal > external cartoid A.
40
what is the safety factor in the transport of blood to the brain
circle of willis
41
what Artery enables the blood to pass from vertebra and carotid A. into the circle of willis and into the brain?
basilar A.
42
briefly what is the blood brain barrier?
unless you are lipid soluble of can use active transport of glucose or AA, nothing can pass the blood into the brain
43
what structure fuses to form tight junctions with the capillary?
astrocytes
44
what is sensation?
its the awareness of sensory stimulation
45
what is perception?
the understanding of a sensation’s meaning.
46
is the energy of a sensory stimulus directly perceived?
no
47
what is the thing produced by the sensory stimulation that is perceivable?
only the neural activity is perceived
48
what law is being described
regardless of how the sensory receptor is activated, the sensation felt corresponds to that of which the receptor is specialized for
law of specific nerve energies
49
when you rub your eyes and see light, what is that an example of?
law of specific nerve energies
50
what law is being described
regardless of where in the brain you stimulate a sensory pathway, the sensation will always be felt at the sensory receptors location
law of projection
51
the somatic sensory cortex is electrically stimulated and causes for patients to percieve somatic sensations in their bodies, what is this an example of?
law of projection
52
the feeling of pain in “phantom leg” of amputees is an example of what?
law of projection
53
what is a modality?
a general class of a stimulus
54
what is the modality encoded by?
labeled-line code
55
what is labeled-line
the brain knows the modality and location of every sensory afferent
56
how do sensory receptors function?
1. stimulus energy interacts with the receptor membrane
2. transduction, involving activation of ions channels if Action Potential is sufficient
3. information is sent to the brain (afferent)
57
do receptor cells accept all stimulus and respond to them all?
no, receptor cells are specific and require for the adequate stimulus in order to respond to it
58
what is the stimulus energy converted into?
afferent activity
59
what are the steps involved in the conversion of stimulus energy?
stimulus energy causes for the opening of ion channels (membrane depolarization)
threshold is reached= production of action potential
propagation of action potentials= release of neurotransmitters into the CNS
60
what happens if the stimulus energy is subthreshold?
the magnitude of receptor potential is low along with the frequency of the action potentials thus preventing the release of neurotransmitters
61
what is considered to be a weak stimulus?
a weak stimulus will cause for the receptor potential to be sufficiently big, and the frequency of action potentials to be sufficiently high to release minimum neurotransmitters
62
the strength of the stimulus energy determines what?
if transduction is activated or inhibited
63
what is a property of afferents that allow us to be sensitive to changes in sensory input?
adaptation
64
what type of stimulus changes are associated with rapidly adapting afferents?
fast stimulus changes
65
what type of adaptation will have some stimulus intensity and moderate stimulus changes?
slowly adapting
66
what happens in non adapting afferents?
the stimulus intensity is encoded and the changes are very slow
67
what is the receptor field?
the region in space that activates a sensory receptor or neuron
68
what part of the receptor filed is the most responsive?
the center is the strongest and as periphery is approached, weaker it becomes
69
what is produced when receptor fields overlap?
it produces a population code.
70
what is the relationship between stimulus acuity and receptor field size?
inversely proportional, hence small RF means high acuity and Large RF means low acuity
71
what is acuity?
the ability to differentiate a stimulus from another
72
what can sharpen sensory acuity?
lateral inhibition
73
with lateral inhibition, how does the perception of a stimulus differ?
much sharper perception over a smaller range
74
what mechanisms shape sensory information transmission to the CNS?
top-down
| bottom-up
75
what is a top down mechanism?
the brain will send a signal down somewhere in the body
76
what is bottom up mechanism?
a peripheral organ or body part will send signal to the brain
77
is it possible for a signal to be inhibited before reaching CNS
yes, There are excitatory and inhibitory neurons, and some may be inhibited presynaptically
78
what do sensory neurons respond to?
respond selectively to stimulus modality (type)
79
if light changes color, what afferent is being stimulated?
visual
80
if sounds are getting louder what afferent is being stimulated?
auditory
81
are somatic sensations mediated exclusively by one type of receptor?
no, by several types of receptors
82
what type of receptor is involved in touch?
mechanoreceptors with specialized end organs
83
what is the function of the end organs on mechanoreceptors
allow for selective mechanical info to activate the nerve terminal
84
what composes the superficial layer of the nerve terminal?
meissner’s corpuscle
| Merkel’s disk
85
what is the fluid filled structure that encloses the nerve terminal?
meissner’s corpuscle
86
what part of the nerve terminal is rapidly adapting and responds to light stroking and fluttering
meissner’s corpuscle
87
what are the small epithelial cells that surround the nerve terminal?
merkel’s disk
88
what part of the nerve terminal is stimulated by pressure and texture and is slowly adapting
merkel’s disk
89
what composes the deep layer of the nerve terminal?
pacinian corpuscle
| ruffini endings
90
what are the large concentric capsules of connective tissue that surround the nerve terminal
pacinian corpuscle
91
how to pacinian corpusle respond?
they are rapidly adapting and respond to strong vivrations
92
what are the nerve endings that wrap around a spindle like structure?
ruffinini endings
93
how does ruffini endings respond to a stimulus?
they are responsible for the stretching and bending of the skin (takes the shape of the object)
will be slowly adapting
94
what is propriorecption?
muscle spindles provide a sense of static position and movement of limbs and bodu
95
what activates mechanoreceptors?
the stretching of the cytoskeletal strands
96
what happens when the cytoskeletal strands are stretched?
deformation of the nerve terminal
activation of action potentials
opening of ions channels via mechanical energy from the mechaoreceptors
97
how is temperture detected by the touch?
thermoreceptors contain ion channels that respond to different temperature ranges
98
what will activate cold afferents?
menthol
99
what temperature will be detected by cold afferents
0-35 degrees
100
what temperature will be detected by warm afferents
30-50 degrees
101
what can activate war afferents?
| what type of sensation is obtained?
capsaicin and ethanol
| will cause for a burning sensation
102
what will be activated by extreme temperatures?
pain receptors
103
what receptors are activated by pain?
nociceptors
104
what are nociceptors?
free nerve endings containing ion channels that open in response to intense mechanical deformation, excessive temperature or chemicals
105
what will activate visceral pain receptors?
inflammation
106
what afferent is highly modulated?
pain afferents
107
what may sensitize nociceptors?
chemicals
108
how is pain encoded?
1. stimulus is percieved (cut by knife)
2. activation of receptors
3. substance P gets released
4. pain is felt
5. tissue is damaged, sensitization of surrounding nociceptors by injured tissue, afferent feedback onto mast cells
6. dilation near blood vessels
109
what term is used to describe feeling pain?
hyperalgesia
110
how is touch an proprioception received in the brain?
passes through dorsal root, ascends to medulla and goes up contralateral in to somatosensory cortex
111
how is temperature and pain received by the brain?
passes through dorsall root and crosses contralateral where it asecends to somatosensorty cortex
112
what part of the body has the highest acuity?
fingers
113
relative to the somatosenory cortex, what does the somatotopic map look like?
laterally: head
center: arms
medially legs
114
what causes for referred pain?
visceral and somatic pain afferents commonly synapse on the same neurons in the spinal cord
115
what is referred pain?
pain that originated at one place (from one organ) but is felt on the skin region elsewhere
116
what type of pathway regulates nociceptive information?
descending pathways
117
describe the concept of descending pathways
pain will travel up to the midbrain and will descent into the spinal cord and inhibit pain by inhibiting afferents and secondary neurons
118
what in analgesia?
inability to feel pain
119
what are opitate neurotransmitters important for?
regulation of pain
120
what is commonly used to regulate opitate neurotransmitters?
drugs such as morphine which will inhibit release of substance P in the spinal cord
121
what parts of the eyes serve to refract light?
cornea and lens
122
between the 2 refracting surfaces of the eye, which refracts more?
the cornea will refract more light
123
what does the lens accomodate for?
changes in object location
124
what are the muscles that control the shape of the lens?
ciliary muscles
125
what is an other name for someone who is nearsighted?
myope
126
what happens in nearsightedness?
the refraction occurs prior to the retina because the eye is too long
127
what is farsighted?
someone who can not see well from close (hyperopic)
128
what happens in farsightedness?
eye ball is too short and the image will be refracted behind the retina
129
identify the following condition
| the lens/cornea is not spherical
astigmatism
130
identify the following condition
| the lens gets stiff and is unable to accommodate for near vision
presbyopia
131
what is cataract?
changes in lens color
132
what part of the eye has the highest acuity, and is where the rods and cones are located?
fovea centralis
133
where is the blind spot located?
optic disk
134
what does light strike at the back of the eye?
retina
135
when is a image said to be in focus?
when the light hits the retina, it will be perceived in focus
136
what part of the eye allow for the eye to accommodate?
the shape of the lense will change
137
in nearsightedness, where is the light refracted and why?
the light is refracted in front of the retina due to excessive bending
138
why does the image end up behind the retina in farsightedness?
insufficient refraction
139
where must light travel to?
the photoreceptors located at the back of the eye
140
what must the rods and cones be close to and why?
close to the pigment epithelium in order to interact with it
141
where does transduction occur
in the photoreceptors
142
what is the function of ganglion cells?
they fire action potentials that go to the optic nerve
143
what does light activate in phtotransduction?
it activates opsin molecules which change shape and desactivate
144
when are there more G proteins? in light or in dark?
in the dark
145
when are Na+ channels open?
in the dark (depolarizes)
146
what happens when cGMP is converted to GMP
the Na channels closes (hyperpolarizes)
147
what does the depolarization cause to be released in the dark?
neurotransmitters
148
what happens when photons hit the chromophore?
induces conformation change of the opsin molecules
activates g protein cascade
conversion of cGMP into GMP which causes for sodium channels to close and stop the release of neurotransmitters
149
what are some properties of rods
```
-for night vision
higly sensitive to ligth
-rhodopsin
-high amplification
-slow response time
-more sensitive to scattered light
-low acuity
-no color
```
150
what are some properties of cones
- day vision
- low sensity to light
- lower amplification
- less opsin
- faster response
- sensitive to bright intense light
- high acuity
- color vision
151
how many opsions are found in codes?
3
152
what is dark adaptation?
going from bright light to a dark environment
153
what type of change occurs in dark adaptation?
in bright light rods are saturated and inactive while the cones are activated
in dark light, we have temporary blindness until the rhodopsin moelcules build up and put back together
154
what is light adaptation?
from dark to light environment
155
what type of change occurs in light adaptation
in dark the cones are inactive and the rods active, however when switching to light temporary blindness occurs until the cones take over, the rods go nuts do the bright light causing for a conformational change that will stop them from working
156
what type of receptor fields are present in retinal ganglion cells?
center surround receptive fields
157
what happens if bright light is flashed only at the center RF in light center, dark surround?
only the action potential is field
158
what happens when bright light is flashed on the surrounding region in light center, dark surround?
inhibits the cell and no action potential is fired
159
what happens if bright light is flashed only at the center RF in dark center, light surround?
inhibits the cell and no action potential is fired
160
what happens if bright light is flashed only at the surround RF in dark center, light surround?
the action potential is field
161
what happens when their is uniform light on the cell?
indeed, the amount of action potentials fired will cancel out and yield no net change
162
what do retinal ganglions signal the difference of across their RFs?
the difference in light (contrast)
163
what are photoreceptors sensitive to?
wavelength
164
what are the 4 types of opsin molecules
- blue cone
- rods
- green cones
- red cones
165
what is determined by the opsin molecule?
the chromatic sensitivity of the photoreceptor
166
what is the component that varies between the cones, what stays constant?
the protein found within the cones will vary but the opsin stays the same
167
how are the RFs of retinal ganglion cells for color?
color opponent RFs (center surround RF with color)
168
what is being compared in center surround RF with color?
the color in the middle to that of the surround
169
what gets encoded by the output of the retina?
relative values of brightness and color
170
what are the 2 possible color sets?
- red and green
| - blue and yellow
171
what is color blindness?
inability to see color due to the lack color sensitive pigments in the cone cells
172
what type of information is carried by the optic nerve?
it carries information from one eye, including both visual fields
173
what part of the eye is responsible for the inversion of the image?
the cornea
174
what type of information is carried by the optic tract?
carries information from both eyes with contralateral receptor fields, hence the right visual fields will be received by the left optic tract and the right optic tract will receive information from the left visual fields
175
what is the optic chiasm?
where the nerves from nasal fibers both eyes cross
176
what fibers do not cross at the optic chiasm?
the fibers closer to the temporal side
177
where is the visual cortex found?
occipital lobe
178
how is the visual cortex generally viewed?
both eyes with contralateral visual fields
179
what happens if there is lesion to the optic nerve?
loss of vision in the ipsilateral (same) eye
180
what happens if there is lesion after the optic tract?
loss of vision in the contralateral fields
this means that if the lesion is on the right optic tract, then the vision of the left fields in both eyes is affected and vice versa.
181
what happens if their is a vertical lesion of the optic chiasm?
bilateral loss the the temporal visual hemifields
thus
the right eye will lose its left visual field
the left eye will lose its right visual field
182
what happens if there is lesion of the optic radiations
loss of vision in the contralateral fields
this means that if the lesion is on the right optic radiation, then the vision of the left fields in both eyes is affected and vice versa.
183
relative to the eyes, what is the left and what is the right visual field
imagine you split eyes in 2, the right will always correspond to your left half hence contralateral relation
184
how are the RF of the primary visual cortex?
small
185
what types of images are perceived in the primary visual cortex?
simple image features such as line segments
186
what does the temporal visual stream allow to recognized?
recognition of things (what)
187
how are the RFs in the temporal visual stream?
large RF
188
what does the parietal visual stream allow to recognize?
spatial features and sensitive to motion (where things are)
189
how are the RFs of the visual parietal stream?
large RF
190
what is perceived polymodal?
its a mix between visual and other sensory modalities which are combined which allows to put visual information together
191
what is sound a result of?
pressure waves that are going around the head
192
what happens when the particles of air get closer together?
pressure increases,
193
how is the frequency measured?
hertz
194
what is the frequency a measurement of?
the # of cycles (pressure wave)/second
195
what does sound amplitude determine?
the loudness of the sound perceived
196
how is the amplitude measured?
in dB
| 20Xlog(frequency)
197
what does a lower threshold mean?
means that hearing is more sensitive (low sounds are not well tolerates
198
how are the thresholds ordered?
- threshold
- damage threshold
- pain threshold
199
what is the function of the pinna?
helps determine where the sound is coming from (up or down)
200
what are the name of the 3 small ear bones?
malleus, incus, stapes
201
what is another name for the eardrum?
tympanic membrane
202
what is the function of the eardrum?
it separates the external from the middle ear
203
what happens to the eardrum when air particles move
it vibrates
204
what is the opening in the middle ear that connects to the throat and helps with pressure?
eustachian tube
205
what is the middle ear filled with?
air
206
what is the role of the semicircular canals?
gives sensitivity to head circulation
207
what angle separated the semicircular canals?
90 degree angles
208
where are the round and oval window?
they are openings found in the inner ear
209
what part of the inner ear is the cochlea?
it is the rolled up part (shell like structure)
210
how does the flow of sound energy function?
1. air particles push on the eardrum which pushes the 3 bones (mallus, incus, stapes)
2. bones are modulated by skeletal muscles which prevent them from moving (flow of fluid) limiting the perception of sound
3. ear drum pushes back and forth on oval window causing it to be pulled while the round window gets pulled in
4. amplification of bones pushes fluid in the cochlea
5. fluid travels down to round window
6. pressure wave causes basilar membrane to vibrate
211
what does the motion of the basilar membrane depend on?
depends on frequency
212
what happens to the basilar membrane at high frequency?
vibrate towards the front
| causing a stiffer part of the membrane to vibrate
213
what happens to the basilar membrane at low frequency?
a less stiff part of the membrane will vibrate
214
what type of frequency is contained in complex sounds? what happens to the basilar membrane?
complex sounds contain various frequencies causing for vibrations to occur in various places
215
what is the basilar motion converted into
neuronal activity at the organ of corti
216
what is the organ of corti?
lines the basilar membrane at the bottom of the cochlear duct
place where vibrations are transduced into neuronal activity
217
what happens when air particles vibrate
causes for the tympanic membrane to vibrate
218
what does the deflection of the basilar membrane produce
shearing of the hair cells sterocelia
219
what is found on the inner and outer membrane of the organ of corti?
hair cells
220
what is the bundle of hair found on hair cells called?
sterocilia
221
the sterocilia are pressed close to what membrane?
tectorial membrane
222
what is the movement of the basilar and sterocilia related to?
the opening and closing of ion channels
223
what do the tip links connect?
they connect each sterocilia
224
what do hair cell contain?
mechanoreceptors
225
how are the hair cells sterocilia stacked?
from short to tallest
226
what do tiplinks do?
they pull on the membrane of the mechanically gated ion channels and open by the strings
227
what do tip links gate?
the ion channels in the sterocilia
228
what is activated by the mechanotransduction at the tip link?
activation of afferent neurons
229
what happens when the ion channel is opened?
potassium gets pulled in (higher amount of potassium in cochlear duct than in as opposed to other cells)
230
what does the flow of potassium cause?
depolarization of the cell allowing to reach threshold and activate afferent neurons
231
what effect does the depolarization have on Ca2+
it will enter the cell and cause neurotransmitters to be released allowing afferent neuron to continue to fire action potentials
232
what happens when the cell hyperpolarizes
- hyperpolarization is caused by the closing of the gate
- k+ stops flowing in
- action potentials are not fired anymore
233
which type of transduction is faster between visual and auditory?
-auditory
234
what happens to tip link if exposed to extremly loud sounds
they will break (causing for hearing of ringing) eventually they will grow back
235
does auditory need amplification like visual transduction?
no
236
in comparaison to opsin molecules, do we have more or less tip links
a lot less tip links than opsin molecules
237
are sound waves generally high in energy?
no, low energy, however present all around hence easier to catch
238
what cranial N. carries auditory info up the brains stem?
8th cranial nerve
239
why does the auditory pathway function in a bilateral representation?
allows brain to localize sound
240
where does the auditory info synapse in the brain and where does it pass after?
synapses at the medulla and makes it way up to mid brain and thalamus before moving laterally to the primary auditory cortex
241
what us the function of the vestibular system?
allows to detect the positions in which the body is
242
what is tinnitus?
ringing in the ears after loud noises
243
is the ear a vestibular organ?
yes
244
what is the function of a vestibular organ?
gives information to the body
245
what is the function of the semicircular canal?
tells info about the heads rotation
246
what is the function of the utricle and saccule
gives info about linear acceleration
247
what gives info about horizontal movement?
utricle
248
what gives info about verticle movements?
saccule
249
what is the role of the vestibular ocular reflex
it enables to keep images clear while the head is moving
250
what happens to the gaze when the head is moving?
no change
251
what is the semicircular canal filled with?
fluid
252
what is the name given to the buldge of the semicircular canal?
ampula
253
what do the hair cells in the semicircular canal line and attach to?
they line the ampula and attach to the bone
254
in the semicircular canal, where do the sterocelia stick out into?
into the cupula
255
what happens to the hair cells when the head moves?
they also move because they are attached to the bone
256
what happens to the fluid when the head moves?
- Inertia causes it to lagg behind and puts pressur on the capula causing it to bend
- the bend of capula causes the bend of the sterocilia which are found inside the capula
257
where are otholits found?
they float above sterocilia
258
what happens when the otholits lag and cause sterocilia to bend?
transduction can occur
259
what do we feel rotation/dizzy when drinking alcohol?
-affects blood brain barrier causing lagging of otholiths
260
what is the function of taste buds?
its where the saliva will dissolve molecules and send the signals
261
where are taste buds located?
in the papillae
262
where is the signal of taste afferents carried to?
to the brain
263
how are salty foods tasted?
Na+ dissolves causing for depolarization, firing AP and releasing neurotransmitters
264
what impacts the level of sourness tasted?
the amount of H+ ions present
265
how is sour foods tasted
the presence of H+ ions will block the k+ and Na+ to enter the channels
266
what is bitter tastes an indicator of?
harmful substances
267
what do bitter substances cause?
they block K+ ions or will bind to various receptors and activate Gprotein cascades causing the depolarization and firing of AP
268
why take salt prior to drinking tequilla?
salt will saturate gestation allowing not to taste the bitterness of tequilla, then with the lemon you can remove tast by blocking Na+ channels
269
what do sugar receptors activate?
G protein cascade which eventually fires AP
270
what type of receptor is activated in umami?
glutamate receptor
271
what will the activation of glutamate receptors in umami lead to?
g protein cascade
