1
Q
functions of the nervous system
A
-sensory input
-integration
-homeostasis
-mental activity
-control
2
Q
what are the components of the nervous system
A
brain, spinal cord, nerves, sensory receptors
3
Q
what are the subdivisions of the nervous system
A
-central nervous system (CNS)
–brain & spinal cord
-peripheral nervous sytem (PNS)
–sensory receptors & nerves
4
Q
what is the PNS composed of
A
-sensory receptors
-nerves
-ganglion
-plexus
5
Q
what are sensory receptors
A
endings of neurons or specialized cells that detect temp, pain, touch, pressure, light, sound, & odors
6
Q
where are sensory receptors
A
skin, muscles, organs, etc
7
Q
what is a nerve
A
a bundle of axons & sheaths, it connects CNS to sensory receptors, muscles, & glands
8
Q
what are the two types of nerves
A
cranial nerves & spinal nerves
9
Q
cranial nerves
A
originate from brain
-12 pairs
10
Q
spinal nerves
A
originate from spinal cord
-31 pairs
11
Q
what are ganglions
A
neuron cell bodies outside the CNS
12
Q
what are plexus
A
axons outside CNS
13
Q
how many pairs of cranial & spinal nerves are in the nervous system
A
12, 31 respectively
14
Q
nerves connect to all the following structures except
a. nerves
b. glands
c. muscles
d. cartilage
A
d. cartilage
15
Q
what are the divisions of the PNS
A
-sensory (afferent)
-motor (efferent)
16
Q
sensory
A
-afferent
-transmits action potentials from receptors to CNS
17
Q
motor
A
-efferent
-transmits action potentials from CNS to effectors (muscles, glands)
18
Q
what does the motor division of PNS contain
A
-somatic NS
-autonomic NS (sympathetic, parasympathetic, enteric)
19
Q
is somatic NS voluntary or involuntary
A
voluntary
20
Q
somatic NS
A
AP’s from CNS to skeletal muscles
-voluntary
21
Q
how many neurons in somatic NS
A
-single neuron system
22
Q
where are cell bodies in somatic NS
A
cell bodies located within the CNS
23
Q
what is a synapse
A
axons forming the junction of a neuron with another cell
24
Q
what is a neuromuscular junction
A
synapse between the neuron & a skeletal muscle fiber
25
autonomic nervous system
ANS
-CNS (brain and spinal cord) to smooth & cardiac muscle; glands
-involuntary control
26
is ANS under voluntary or involuntary control?
involuntary
27
how many neurons in autonomic nervous system
two neuron system
-CNS to ganglion & ganglion to effector
28
what are the divisions of the autonomic nervous system
-sympathetic
-parasympathetic
-enteric
29
when is sympathetic most active
most active during physical activity
(fight or flight)
30
what does parasympathetic nervous system do
regulates resting functions: such as digested food, emptying the bladder
31
where is enteric found
plexus in wall of digestive tract (reflex)
32
what is the organization of the nervous system
receptor - sensory NS - CNS - motor NS - effector
33
what are neurons & what do they do
(nerve cells)
-receive stimuli & transmit action potentials
34
what is the organization of neurons (the parts)
-dendrites: input
-cell body: or called soma
-axons: output
35
what is the role of neuroglia
(glial cells)
-support & protect neurons
36
what are the parts of a neuron 25
-cell body: nucleus, nissl bodies
-dendrites: short, often highly branched
-axons: can branch
37
what does the cell body consist of
nucleus & nissl bodies
38
what are nissl bodies
-chromatophilic substance
-rough ER: primary site of protein synthesis
39
what are dendrites like
they are short & often highly branched
-have dendritic spines
40
what are dendritic spines
little protuberance where axons synapse with dendrites
41
where do axons synapse with dendrites
the dendritic spine
42
what are axons like
they can branch & have collaterals
-(branches that extend from the main axon of a neuron, allowing it to transmit signals to multiple target cells or regions simultaneously)
43
axon hillock
single axon arises
44
initial segment
beginning of axon
45
what makes up the trigger zone
axon hillock & initial segment
46
what is the trigger zone
site where action potentials are generated
47
what is the axoplasm
cytoplasm of the axon
48
what is the axolemma
axons plasma membrane
49
where are synaptic vesicles
within presynaptic terminals
50
what is the end of an axon called
presynaptic terminals (terminal boutons)
51
what are the axonic transport mechanisms
-away from the cell body
-into the cell body
52
what is the axonic transport mechanism away from the cell body like
can move proteins, organelles, & vesicles away from the cell body to the presynaptic terminal
-supplies for growth, repair, & renewal
53
what is the axonic transport mechanism into the cell body
damaged organelles, recycles plasma membrane, & substances (taken in by endocytosis) can be transported up the axon to the cell body
(rabies & herpes virus into the CNS)
54
where do damaged organelles go
into the cell body, up the axon
55
where do proteins go
towards the presynaptic terminal away from the cell body
56
what are the types of neurons in a functional classification
1. sensory (afferent)
2. motor (efferent)
3. interneurons (association neurons)
57
where do sensory neurons info go
-afferent
-APs toward CNS
58
where do motor neurons info go
-efferent
-APs away from CNS
59
where do interneurons info go
-associated neurons
-APs from neuron to neurons in CNS
60
what are the types of neurons in structural classification
-bipolar
-multipolar
-pseudounipolar
61
multipolar neurons
many dendrites with a single axon
- most neurons in the CNS & motor neurons
62
how are most neurons in the CNS & motor neurons shaped structurally?
multipolar
63
bipolar neurons
1 axon & 1 dendrite
-sensory in retina of the eye & nose
64
what shape or most sensory neurons?
pseudounipolar
65
pseudounipolar neurons
a single process
-divides into two branches
-most sensory neurons are this shape
66
what do astrocytes promote
formation of the blood brain barrier
67
where are astrocytes?
in the CNS
-neuroglia
68
where do astrocytes processes form?
feet of the neuron
69
what do astrocytes cover?
surface of neurons & blood vessels
70
what do astrocytes regulate
extracellular brain fluid composition
71
what do astrocytes allow & prevent
allow: exchange of nutrients & waste products between neurons & blood
prevents: fluctuations in blood composition from affecting the brain
72
what do astrocytes protect neurons from
toxic substances
73
what do astrocytes determine about substances
what can pass from the blood into the nervous tissue of the brain & spinal cord
74
what is the structure of astrocytes & why is it like that
-extensive cytoskeleton of microfilaments for support of blood vessels & nerves
75
where are ependymal cells?
in the CNS
-neuroglia
76
what do ependymal cells line
brain ventricles & spinal cord central canal
77
what do ependymal cells form
with blood vessels & support tissues they form choroid plexuses
78
what are choroid plexuses
structures in the brain's ventricles that produce and secrete cerebrospinal fluid (CSF) and form the blood-CSF barrier
79
what does cilia do in ependymal cells
help move the CSF fluid through cavities of the brain
80
where is microglia?
in the CNS
-neuroglia
81
what happens to microglia in response to inflammation?
become mobile & phagocytic in response to inflammation
82
what does microglia phagocytize
necrotic tissue, microorganisms, & foreign substances that invade the CNS
83
what shows evidence of damage in an autopsy
they can see microglia migrate to the damaged area
-seen in infection, trauma, or stroke
84
where are oligodendrocytes
in the CNS
-neuroglia
85
what do oligodendrocytes do
form myelin sheaths if they surround an axon many times
86
how many oligodendrocytes does it take to form myelin sheaths?
a single one can from myelin sheaths around portions of several axons
87
where are schwann cells?
PNS
88
what are schwann cells also called?
neurolemmocytes
89
what do schwann cells do?
they wrap many times around a portion of only one axon
-forms myelin sheath
-they are myelinated
90
what is like schwann cells in the CNS?
oligodendrocytes
91
what are unmyelinated axons
axons that are contain no myelin
-this is called gray matter
92
myelinated axons
-myelin protects & insulates axons from one another
-speeds transmission of AP's "white" matter lipid
-has nodes of ranvier
93
how old are you when myelin sheaths stop forming rapidly
1 yr
94
what happens with degradation of myelinated sheaths?
-you will get multiple sclerosis & the APs slow
95
do both cns & pns contain areas of white matter?
yes
96
what matter is it when axons form bundles?
white matter
97
what matter is it when neuron cell bodies & their dendrites are grouped together?
gray matter
98
what does gray matter consist of
groups of neuron cell bodies & their dendrites with very little myelin
99
what is gray matter on the surface of the brain called in CNS?
the cortex
100
what is the gray matter in deeper clusters called in CNS?
nuclei
101
what is a cluster of neuron cell bodies called in PNS?
ganglion
-a ganglion is a structure made of gray matter
102
A cluster of neuron cell bodies in the peripheral nervous system (PNS) is called a ________. These are distinct from ______, which are clusters of neuron cell bodies in the central nervous system (CNS).
ganglion
nuclei
103
what is white matter
bundles of parallel myelinated axons
104
what does white matter of the CNS form?
nerve tracts that propagate AP's from one area of the CNS to another
105
what is white matter of the PNS ?
bundles of axons & their connective tissue sheaths called a nerve
106
what are nerves part of? (which system)
PNS
107
what system are satellite cells in?
PNS
108
what do satellite cells do?
surround neuron cell bodies in a sensory ganglia; providing support & nutrients to the neuron cell bodies
109
what are satellite cells similar to?
astrocytes in the CNS
110
what do satellite cells protect neurons from?
heavy metal poisons such as lead & mercury by absorbing them & reducing their access to the neuron cell bodies
111
choose the pair of terms that does not go together?
a. autonomic, voluntary
b. somatic, voluntary
c. autonomic, involuntary
d. somatic, skeletal muslces
a. autonomic, voluntary
112
how do cells transfer info?
through action potentials?
113
action potentials
electrical signals produced by cells
114
what do electrical properties result from?
-ion concentration differences across plasma membrane (inside & outside)
-permeability of membrane to ions
115
what are ion concentrations of the cell due to?
-Na/K pump
-membrane permeability
116
what ions are at high concentration outside the cell?
Na+ & Cl-
117
what ions are at high concentration inside the cell?
K+ & proteins-
118
what charge do proteins have
negative
119
how many ions are going in & out of the sodium potassium pump?
3 Na+ out
2 K+ in
120
are proteins made inside or outside the cell?
inside
121
can proteins cross the membrane?
no
122
what are the types of gated ion channels
voltage gated & ligand gatted
123
what happens with chlorine? how does it move out of the cell?
chlorine is negative & so its repelled by the negative proteins in the cell so its pushed out through nongated Cl- channels
124
do non-gated channels open & close?
no, they're always open
125
what are nongated channels (always open) channels responsible for?
membrane permeability to ions when the PM is unstimulated or at rest
126
what two ions are there more nongated channels for?
K+ & Cl-
127
at rest, more ____ & ____ are moving than ____
K+ & Cl-
Na+
128
why does K+ move outside the cell?
since there is a higher concentration inside the cell of K+ than outside, so it diffuses out
129
leak channels
a. open in response to small voltage changes
b. open when a chemical signal binds to receptor
c. allow substances to move into the cell but not out
d. are responsible for resting membrane potential (K+ leak channels) in the resting plasma membrane
d. are responsible for resting membrane potential (K+ leak channels) in the resting plasma membrane
130
what are the 4 types of gated ion channels
1. ligand gated
2. voltage gated
3. touch receptors
4. temperature receptors
131
what is the most common voltage gated?
Na+ & K+
132
what opens gates in touch receptors
mechanical stimulation of the skin
133
what opens gates in temperature receptors
temperature changes in skin
134
at resting membrane potential, what occurs?
-the number of charged ions inside = outside
-concentration of K+ higher inside, Na+ higher outside
135
what is the potential difference
electrical charge difference across the plasma membrane is -70 to -90 mV
136
greater the charge different =
greater potential difference
137
mV in nerve
-70
138
mV in skeletal muscle
-85
139
which has greater potential difference, skeletal or nerve?
skeletal since its more negative
140
the potential difference _________ as you depolarize
decreases
141
when is the resting membrane potential established?
when the movement of K+ out of the cell is equal to their movement into the cell
142
what happens if extracellular concentration of K+ increases?
not as much K+ will want to go out, since it would be going up its concentration gradient.
there would be a less negative charge inside the cell so depolarization would start to take place & we would have a less polar membrane
143
what happens if extracellular ion concentration of K+ decreaes?
we would have a steeper gradient (difference) between inside & outside.
hyperpolarization would start to take place and we would have a more polar membrane
144
which of these terms is matched correctly?
a. depolarization: membrane potential becomes more negative
b. hyperpolarization: membrane potential becomes more negative
c. hyperpolarization: membrane potential becomes more positive
b. hyperpolarization: membrane potential becomes more negative
145
what happens if you change the concentration of Na+ inside or outside the cell?
very little effect (gates close)
146
what happens with Na+ if you open gates (like when Ach attaches to ligand receptors) ?
Na+ diffuses in & we would see depolarization of the membrane?
147
what are voltage-gated Na+ channels sensitive to?
changes in extracellular Ca2+ concentrations
148
what happens if extracellular Ca2+ concentration decreases?
Na+ gates open leading to depolarization
149
what happens if extracellular concentration of Ca2+ increases?
Na+ gates close & membrane repolarizes (hyperpolarized)
150
what is hypocalcemia phentoypically
uncontrolled contraction of skeletal muscles - tetany
151
what is hypocalcemia on a more biological level?
increased membrane permeability to Na+
-since Na+ causes lots of action potential when inside the cell, leading to the muscle to not be able to stop flexing
152
what is a graded potential
-local potential
-a small change in the RMP confined to a small area of the plasma membrane
153
graded potential compared to action potential
-graded potential is in a small area
-ap is over entire surface of cell & is a larger change in the RMP that reaches threshold
154
can local potential result in an action potential?
yes!
155
is a local potential an action potential?
no!
156
what do graded potential result from?
-ligand binding
-changes in charge (voltage)
-mechanical stimulation
-temperature changes
-spontaneous change permeability
157
do graded potential reach threshold?
they can, leading to an action potential
158
can graded potential summate?
yes- they can add on to each other
159
graded potential
a. always cause an action potential
b. never summate
c. can travel over long distances
d. are confined to a small region of the plasma membrane
d. are confined to a small region of the plasma membrane
160
what is an action potential
permeability changes when a local potential causes depolarization of membrane
161
what principle do APs follow
all or none principle
-if stimuli is greater than threshold, you get an action potential
162
what makes up the refractory period?
absolute
relative
163
absolute refractory period
beginning of AP to near end of repolarization
-no matter how large a stimulus, no second action potential
-complete insensitivity exists to another stimulus
164
relative refractory period
a stronger-than-threshold stimulus can initiate another action potential
165
what is the AP frequence
number of APs produced per unit of time to a stimulus
166
what is a supramaximal stimulus
stronger than maximal - cannot produce a greater frequency of action potentials than maximal stimulus
167
what happens with action potential propogation
AP at one site causes AP at next location by stimulating voltage gated Na+ channels in adjacent regions of the membrane
-cannot go backwards (refractory period) so one-way conduction
168
what is saltatory conduction
myelinated
-the process by which an action potential "jumps" from one node of Ranvier to the next along a myelinated axon
169
what increases speed of conduction?
myelination
170
what makes myelin faster?
thicker myelin sheath
larger diameter: nerve has greater surface area & more voltage-gated Na+ channels
171
what are the nerve fiber types
-type A
-type B
-type C
172
about type A nerve fiber
-large diameter
-myelinated
-conduct APs at 15-20 m/s
-found in most sensory neurons & motor neurons to skeletal muscle
-react fast to external environment
173
about type B nerve fibers
-medium-dimater
-lightly myelinated
-conduct APs at 3-15 m/s
-part of ANS stomach, intestines, heart
174
about type C nerve fibers
-small diameter
-unmyelinated
-conduct APs at <2 m/s
-propagate AP's through entire axon's membrane, so much slower
-part of ANS digestive organs, heart
-response to maintain homeostasis for things like digestion need not be as fast
175
what are the types of synapse
-electrical synapse
-chemical synapse
176
what is a synapse
a junction between two cells where they communicate with each other
177
what are the types of cells in a synapse
-presynaptic: transmits signal toward the synapse
-postsynaptic: cells that receive signal
178
what cells in a synapse receive the signal?
postsynaptic cells
179
what cells in a synapse transmit signals towards the synapse
presynaptic cells
180
what are electrical synapses
gap junctions that allow local currents to flow between cells through connexons (protein tubes)
181
where are electrical synapses found
in cardiac and smooth muscles
182
what do electrical synapses allow for
coordinated contractile activity among groups of cells
183
what are the components of chemical synapses
presynaptic terminal
synaptic cleft
postsynaptic membrane
184
what are neurotransmitters released by
action potentials
185
what structure contains neurotransmitters that are released at the synapse?
synaptic vesicles
186
what triggers the release of neurotransmitters from synaptic vesicles?
Ca²⁺ entering the presynaptic terminal when the action potential arrives
187
what causes neurotransmitter release from the presynaptic neuron?
an action potential reaches the presynaptic terminal and opens voltage-gated Ca²⁺ channels, causing Ca²⁺ to enter and trigger neurotransmitter release.
188
what happens to the neurotransmitter after it’s released?
it diffuses across the synaptic cleft to the postsynaptic membrane.
189
what does the neurotransmitter do at the postsynaptic membrane?
it binds to ligand-gated Na⁺ channels and causes them to open.
190
what happens when ligand-gated Na⁺ channels open on the postsynaptic membrane?
Na⁺ enters the cell, causing depolarization.
191
when does the postsynaptic neuron fire its own action potential?
if enough Na⁺ enters to reach threshold.
192
do two action potentials occur in one neuron during synaptic transmission?
no
-one action potential in the presynaptic neuron triggers a new action potential in the postsynaptic neuron.
193
what are the ways neurotransmitters are removed?
-enzyme broken down
-recycled
-diffuses
194
how does ACh get removed?
acetylcholine splits ACh = acetic acid + choline
(enzyme broken down)
195
how does norepinephrine (NE) get removed?
-recycled (taken up)
-diffuses (goes away)
196
neurotransmitter substances are stored in vesicles located in specialized portions of
a. soma
b. axon
c. dendrite
d. nucleus
b. axon
197
in a chemical synapse, neurotransmitters have short-term effects because
a. neurotransmitters (NT) can diffuse away from the synapse
b. NT can be broken down by enzymes
c. NT can be taken up by the presynaptic terminal
d. all of the above
d. all of the above
198
neurotransmitters can be _________ in some synapses & _________ in others
-excitatory
-inhibitory
199
what are neuromodulators
substances released from neurons
200
what can neuromodulators do
influence (one way or another) the likelihood that an AP in the presynaptic terminal will result in an AP in the postsynaptic terminal
201
what is amphetamine
a neuromodulator
202
how does amphetamine have excitatory effects on the CNS?
-it increases levels of NE in the synaptic cleft
-decreases appetite
-increases alertness
-enhances ability to concentrate for ADHD & depression
203
how does amphetamine increase the levels of neurotransmitters in the synaptic cleft?
-increases to release of NE from synaptic vesicles in presynaptic neuron
-block the reuptake of NE from synaptic cleft
204
what is prozac or zoloft used to treat
depression
205
what does prozac and zoloft do?
-its an ssri
-ssri blocks serotonin transporters resulting in increased serotonin levels in the synaptic cleft
206
what are axoaxonic synapses
when the axon of one neuron synapses with the presynaptic terminal (or axon) of another
-there are many of these in CNS
207
where are axoaxonic synapses
many of them are in CNS
208
what is presynaptic inhibition
reduction in amount of neurotransmitter released from presynaptic terminal
-(enkephalins & endorphins can inhibit pain sensation)
209
what do opiates like morphine do?
bind to endorphin & enkephalin receptors on presynaptic neurons
210
how do opiates like morphine reduce pain?
by blocking the release of a neurotransmitter (substance P is NT in pain transmission)
211
what does presynaptic facilitation do
increases neurotransmitter released from presynaptic terminal
212
what does serotonin do?
acts as a neuromodulator that increases the release of neurotransmitters by causing the CA channels to open
213
what does caffeine do?
indirectly stimulates the release of glutamate in the brain
-blocks the adenosine receptors & keeps adenosine from doing its job (adenosine makes you drowsy)
213
what is a major excitatory NT in the CNS?
glutamate
214
what blocks the release of glutamate from the presynaptic terminal & helps regulate it?
adenosine
215
what does caffeine promote?
alertness
215
what does adenosine do?
-can cause drowsiness
-blocks the release of glutamate from the presynaptic terminal & helps regulate it
216
what are convergent pathways?
many neurons converge - synapse with smaller number of neurons (synthesis of data in brain)
217
what are divergent pathways?
small number of presynaptic neurons synapse with large number of postsynaptic neurons
a&p
flashcards
Decks in class (21)
# Cards
-
chapter 169
-
a & p lab one40
-
chapter 262
-
chapter 3159
-
a + p lab 233
-
chapter 4184
-
chapter 5149
-
chapter 6144
-
a&p lab exam26
-
chapter 7142
-
chapter 9 (& some of 10)210
-
chapter 11219
-
chapter 12145
-
lab exam46
-
chapter 13126
-
chapter 15285
-
chapter 1694
-
chapter 1795
-
lab exam18
-
exam 6 q16
-
chapter 18107
