1
Q
What is the CNS protected by?
A
-skull and spinal cord
2
Q
What is the CNS covered by?
A
- connective tissue meninges
3
Q
What is the brain?
A
- site of thoughts and intelligence
- processes info received and sends messages to body
4
Q
What is the PNS made of?
A
- nerves and ganglia
5
Q
What are nerves
A
- bundled axons that carry signals to and from the CNS
-extend from brain and spinal cord
6
Q
How are nerves organized?
A
- epineurium
-perineurium
-endonerium
7
Q
What is the epineurium?
A
connective tissue surrounding outer nerve surface
8
Q
What is the perineurium?
A
- connective tissue that surrounds and separates bundles of axons organized into fascicles
9
Q
What are ganglia?
A
cluster of neuron cell bodies outside of the CNS along the length of a nerve in the PNS
- localizeed
10
Q
What are the types of afferent systems?
A
- somatic sensory
-visceral sensory
11
Q
Whats an example of a visceral sensory organ?
A
the heart
12
Q
Whats and example of a somatic sensory organ?
A
- eyes, ears, skin
13
Q
What is the afferent pathway?
A
- sensory nervous system detects stimuli and transmits info from receptors to the CNS
14
Q
What is the somatic sensory system?
A
- sensory input that is consciously perceived from receptors
15
Q
What is the visceral sensory system?
A
- sensory input that is not consciously perceived by receptors of blood vessels
and internal organs
16
Q
What is the efferent sensory system?
A
- motor nervous system that initiates and transmits info from CNS to effectors
17
Q
What are the parts of the efferent sensory system?
A
- somatic motor
- autonomic motor
-sympathetic division - parasympathetic division
18
Q
What is the autonomic motor system?
A
- motor output that is not consciously or involuntarily controlled
19
Q
What are the parts of the efferent system?
A
-sympathetic
-parasympathetic
20
Q
What is the somatic motor system?
A
- motor output that is consciously or voluntarily controlled
21
Q
What is an example of somatic motor system?
A
-effector is skeletal muscle
22
Q
What is the sympathetic division?
A
-fight, flight, or freeze stress response
23
Q
What is the parasympathetic division?
A
- resting and digesting branch
-maintains homeostasis
24
Q
What is an example of the autonomic motor division?
A
- cardiac muscle
-smooth muscle - glands
25
What is a fascicle?
bundle of axons
26
What nervous system do cranial and vertebral nerves a part of?
-PNS
27
Are nerves an organ or a cell?
-organ
28
What are axons bundled by?
- connective tissue layers
29
Are neurons an organ or a cell?
cells
30
What are multipolar neurons made of?
- Multiple processes extend directly from the neuron cell body
- multiple dendrites and 1 axon
31
What type of neuron is the most common?
multipolar
32
What type of neuron are motor neurons and interneurons?
multipolar
33
What are bipolar neurons made of?
- 2 processes extending directly from cell body
-1 dendrite and one axon
34
Where are bipolar neurons found?
- eye retina
-olfactory epithelium of nose
35
What are unipolar neurons made of?
- 1 process attached to cell body/soma
- forms a t-intersection with the 2 processes (peripheral and central) of 1 long axon
dendrites directly attached to the peripheral process of axon
36
Where are unipolar neurons found?
- most sensory organs
37
Which type of neuron are part of ganglion in PNS?
- unipolar neuron
38
What are anaxonic neurons?
- neurons with no axons
39
What are anaxonic neurons made of?
- processes are only dendrites that extend from cell body
40
What are interneurons?
connections between neurons
41
Where are anaxonic neurons fire?
-only in the CNS
42
What are the functional classifications of neurons?
- sensory/afferent
- interneurons
-motor/association neuron
43
What do sensory/afferent neurons do?
- receive somatic and visceral sensory input
- conduct AP signals to the CNS
44
What structural type of neuron are sensory neurons?
- unipolar
- receptive region and cell body in PNS and azon end in CNS
45
Where are interneurons found?
-entirely in CNS
46
What structural type of neurons are interneurons?
- multipolar or anaxonic
47
What do interneurons do?
- receives signals from sensory neurons and sends signals to motor neurons
48
What pathway are motor/association neurons a part of?
- efferent pathway
49
What do motor neurons do?
- conducts motor output from CNS to effectors in the PNS
50
Where are motor neurons found?
- innervate somatic (skeletal) muscle and autonomic effectors (smooth muscle)
51
What are motor neurons made of?
multiple neurons
52
What kind of gaps do electrical synapses have?
- no gap
-has a physical connection
-has a gap junction
-Gap junctions use proteins to create pores for ions
53
What is an electrical synapse?
- junction between 2 neurons that allows for the two way transmission of electrical signals
54
What type of synapse is the most common?
- chemical
55
What kind of gaps do chemical synapses have?
-has synaptic cleft
- no physical connection
56
How do chemical synapses work?
-Electrical signals get turned into chemical signals (NT)
-presynaptic neurons axon terminal which produces signal in the form of NT
-postsynaptic neuron receives signal as NT and binds to receptor and cause a postsynaptic potential
57
What do postsynaptic potentials do?
- depolarization or hyperpolarization
58
What is a pro to chemical synapse?
-allows for variability
-smart
59
What is a pro to electrical synapses?
-fast (but dumb)
60
What do excitatory NT do?
-depolarization, makes membrane more positive
61
What do inhibitory NT do?
-hyperpolarization
-membrane more negative
62
Why is the resting membrane potential negative?
- at the inside is more negative than the outside
-compares membrane innerface to membrane outerface
63
What does anterograde transport do?
moves newly synthesized material toward synaptic knob
64
What do retrograde transporters do?
moves used materials from Axon for breakdown and recycling in the cell body
65
What causes slow transport?
flow of axoplasm?
66
Where does slow transport occur?
within the azon
67
Does slow transport require energy?
no
68
What does slow transport?
- anterograde transport of enzymes, cytoskeleton components, new axonplasm
-diffuses through the axon?
69
Does fast transport require ATP?
yes
70
What does fast transport do?
- components are made in one area of neuron and shipped to another
71
Which way does fast transport go?
- both ways
-anterograde (cell body to axon terminal) or retrograde (axon to cell body)
- Antero moves vesicles, organelles, glycoproteins
- Retrograde can be used to move vesicles
-inside axon
72
What is a negative to retrograde transport?
- can be hacked by infections to effect the cell
73
What do glial cells do?
- support neurons
74
Do glial cells carry Ap?
- no (not firing)
75
What are glial cells
-nonexcitable mitotic support cells found in CNS and PNS
76
Are glial cells excitable?
no
77
Which glial cells are in the CNS?
-oligodendrocytes
-astrocytes
-microglial
- ependymal
78
Which glial cells are in the PNS?
-Satellite cell function
- neurolemocytes
79
Are there more neurons or glial cells?
- glial cells
- 1/2 the volume of the nervous system
80
What are all glial cells good for?
- critical function at neural synapses
81
What do astrocytes do?
- forms part of the blood-brain barrier
-regulates interstitial fluid composition within CNS
- assists with neuronal development
- provides structural support and organization
82
How do astrocytes provide structural support and organization?
- can act as a filler for things like dead neurons
-replicates itself to do that
83
What do oligodendrocytes do ?
- myelinates and insulates axons in the CNS
- has multiple extensions to reach out to various neuron axons allowing one oligodendrocyte cell to multiple neuron axons
84
What does myelin do?
-allows for faster AP conduction
85
What do microglial do?
- phagocytic
-essentially WBCs of the neurons
- monitors neuronal health
86
What do ependymal cells do?
lines ventricles of brain and central canal of spinal cord
-assists with production and circulation of CSF
87
What do satelite cells do?
- electrically insulates PNS
- regulates nutrient and waste exchange for cell
- monitors health
88
What are neurolenmoyctes?
- associated with axon and PNS of neurons
- partially surround unmyelinated axons and form myelin sheaths of myelinated axons
89
What do positive signals do?
- excitatory, depolarizing
90
What do negative signals do?
- inhibitory, hyperpolarization
91
What are dendrites?
-short unmyelinated processes branching off the cell body
92
What do dendrites do?
- receives input and transfers signal to cell body
- receives graded potentials when we have chemically gated channels
93
What does the cell body contain?
nucleus and organelles
94
What does the cell body do?
- receives signals and transfers them to axon hillock region
95
What is the axon hillock?
-contains the initial segment where summation of inputs occurs to determine if threshold is met
96
Can an AP be partially sent?
no
full send only
97
What does AP depend on
voltage gated channels
98
What happens if threshold is met?
- an AP is initiated in the axon Hillock region and conducted down axon
99
Is the axon the receiving end?
no
100
What does the axon do?
conducts AP from azon hilcock region to axon terminal
101
Are all axons myelinated?
no
102
What happens when an AP reaches the axon?
- NTs released from axon terminal (synaptic knob region) in response
103
What are post synaptic potentials?
- graded potentials that change the membrane potential
104
How do AP effectors come in?
-ligand/chemically gated receptors
105
Where do post-synaptic potentials rest?
depolarization or hyperpolarization of the membrane
106
Are all post synaptic potentials the same strength?
- no, they vary in strength and decrease with distance over time
107
How does increasing the distance traveled affect post synaptic potentials?
- they decrease their strength
108
Are ions distributed evenly across the membrane?
no
109
Why aren't ions distributed evenly across the membrane?
- pumps
110
Where are the levels of Na+ higher
extracellular
111
Where are the levels of Cl- higher?
extracellular
112
Where are the levels of Ca2+ higer?
extracellular
113
Where are levels of K+ higher?
intracellular
114
What is the resting membrane potential?
- an electrical charge difference across the membrane (intracellular and extracellular face)
-inside is negative compared to outside
-70mv
115
How is the resting membrane potential maintained?
-leak channels
-NaK+ pumps
116
Do leak channels require ATP
no
117
What has the largest impact on RMP?
leak channels
118
Are there more K+ or Na+ leak channels
K+
119
Does the NaK+ pump require ATP?
yes
- in neurons, NaK+ pump can account for 75% energy expenses
120
What does the NaK+ pump do?
- produces ion movement against the gradient
-3Na+ out
-2K+ in
-(unequal movement of ions)
121
What are the types of receptive sements?
-chemically gated cation
-chemically gated K+
-chemically gated Cl-
122
What do chemically gated cation channels do?
- cause a net influx of Na+
- membrane potential becomes more positive
-causes depolarization
-excitatory
-moves 2 ions
123
What do chemically gated K+ channels do?
- net efflux of K+
-only moves K+
- causes hyperpolarization
- inhibitory
124
What do chemically gated Cl- channels do?
- net influx of Cl-
-movement of only Cl-
-hyperpolarization
-inhibitory
125
What are chemically gated channels caused by?
NT binding
126
Where do chemically gated channels occur?
postsynaptic membrane
127
Can chemically gated channels change the membrane potential?
-yes
-causes temporary small localized change in membrane potential
128
How do signals from gated channels vary?
- direction
-charge (hyper vs depolarization)
-strength of signals
-signals are multidirectional and weaken with distance
129
How do excitatory NT and EPSP get generated?
1. presynaptic neuron releases excitatory NT which binds to chemically gated receptors
2. chemically gated cation channels open, net Na= influx
3, the inside of the neuron becomes more positive
4. EPSP propagates toward axon hillock, and weakens with distance
130
How do inhibitory NT and IPSP get generated?
- inhibitory NT released from presynaptic neurons bind to chemically gated K+ and or Cl-channels
- K+ efflux and or CL- influx causing the inside of the neuron to become more negative
- IPSP propagates towards axon hillock, weakens with distance
131
What is temporal summation?
- the same presynaptic neuron initiates postsynaptic potentials rapidly within a narrow period of time
- like a tempo speeding up
132
How many synapses cause temporal summation?
- a single synapse
133
How does temporal summation change graded potentials?
they cause graded potentials to vary in strength
134
What is spatial summation?
- different presynaptic neurons initiate postsynaptic potentials within a narrow window of time
- looking at different spaces in time, the cumulative effect of released things at the moment
135
What happens if the IPSP and the EPSP are the same strength?
they cancel eachother out
136
How many synapses does spatial summation apply to?
2+
137
What is summation?
the cumulative impact of all simultaneously received graded potentials (IPSP and EPSP)
138
What is threshold?
- + 15mv from RMP
- determines if an AP is initiated due to the opening of voltage-gated channels
139
Can an AP be partially generated?
no
all or nothing
140
Do AP lose intensity as they are propogated?
no
141
Can AP be triggered sub threshold?
no
142
Can you go from a negative number to a positive number when calculating AP propogation?
no it stops at 0
143
What is the charge of threshold?
-55mv
144
Describe voltage-gated Na+ channels.
- have activation and inactivation gate which allow for 3 different receptor states
- once activated receptor state cycles in sequence back to resting
-nothing binds to it, opened by changes in membrane potential (same for K+)
145
What are the three receptor states?
- resting state
-activation state
-inactivation state
146
What is the resting receptor state?
- channel closed
-inactivation gate opened
- activation gate closed
147
What is the activation receptor state?
- channel open
-Na diffuses in
-inactivation and activation gate opened
148
What is the inactivation receptor state?
- channel closed
- activation gate opened
- inactivation gate closed
- lasts a short time, resets quickly
149
What is depolarization and what causes it?
- voltage gated Na+ channels open (activation state)
-Na+ influx makes the inside more positive resulting in a reversal of polarity
- K+ channels closed
-peaks at about 30
150
Describe repolarization and what causes it?
- Na+ channels closed (inactivation state)
- K+ voltage gated channels open
-K+ efflux causes a return to RMP (-70)
151
Describe the return to RMP and what causes it?
- remains at -70 until a new signal is recieved
-maintained by Na+ and K+ leak channels and the NaK+ pump
-all voltage gated channels closed
152
Which receptor state allows movement through channels?
activation state
153
Can both gates be closed in the different receptor states?
no- one gate must always be open
154
What is the absolute refractory period?
-no ap can be generated
-Na+ v-gated channels are not in the resting state
-they are either open (activated) or closed (inactivated)
-ensures Ap only moves forward towards the terminal (synaptic knob)
155
What is the relative refractory period?
- can open but harder
-since its hyperpolarized its harder to get to the threshold
- voltage-gated Na+ channel returned to resting state, but membrane is still hyperpolarized
155
156
What makes sure that AP is a unidirectional movement?
- refractory period
157
What initiates the release of the NT?
synaptic knob
158
What are the steps of myelination in the PNS?
1. neurolemocyte starts to wrap around a portion of an axon
2. neurolemocyte cytoplasm and plasma membrane begin to form consecutive layers around the axon as wrapping continues
3. the overlapping inner layers of the neurolemmocyte plasma membrane form the myelin sheath
4. eventually the neurolemocyte cytoplasm nucleus is pushed to the periphery of the cell as the myelin sheath is formed
159
Where does saltatory conduction occur?
unmyelinated regions of the axon (Nodes)
160
What characterizes nodes?
-no myelin
-high volume of Na+ and K+ voltage-gated channels present
161
What are the advantages of myelinated areas?
-Na+ diffuses through (part of saltatory conduction)
- well-insulated areas that have a limited number of voltage-gated Na+ K+ channels
162
What are the steps in saltatory conduction?
1. Neurofibril (node) initiates Ap by having Na+ diffuse into the axon leading to AP conduction
2. myelinated regions see diffusion through the axoplasm of the axon, the signal becomes weaker with distance
3. next neurofibril nod sees the arrival of the weak Na+ current sufficient to cause opening of voltage-gated Na+ channels and a new AP is initiated
163
Where are NT released from?
-synaptic knob
164
How many NT can one neuron synthesize?
a NT can synthesize multiple NT but can only release one at a time
165
What determines what NT the neuron releases?
- dependent on the frequency of the AP that reaches the knob
166
Why are the NT effects on the postsynaptic membrane is short-lived?
- NT binding is temporary, and NT can diffuse away from the synapse
- NT may be moved back into the neuron through transport proteins and
- NT may be degraded by enzymes located at the synaptic cleft
167
What are the steps to NT transmission?
1. AP reaches the synaptic knob
2. v-gated Ca2+ channels open, Ca2+ enters knob and binds with proteins of synaptic vesicles
3. synaptic vesicles merge with synaptic knob plasma membrane and NT released by exocytosis
4. NT crosses synaptic cleft and attaches to receptors on a muscle or to receptors of a neuron or gland
Bio 240
flashcards
Decks in class (5)
# Cards
