Lecture Exam 2 Flashcards
1
Q
Central nervous system
A
- Brain
2. Spinal cord
2
Q
Reflex
A
Automatic, reproducible response to a stimulus
3
Q
What reflex did we focus on?
A
Neural reflex
4
Q
How do you detect a stimulus?
A
By using a receptor that takes information about a stimulus and sends it to the integration center, which determines if the stimulus requires a response, if a response is needed it sends the information to an effector which responds to the stimulus
5
Q
What is different about a neural reflex from a reflex?
A
The receptor, integration center, and effector are all connected by neurons
6
Q
Pain/withdraw reflex
A
Moves affected parts of the body away from the stimulus
7
Q
Events in a reflex arc
A
- Arrival of stimulus and activation of receptor
- Activation of sensory neuron
- Information processing in the CNS
- Activation of a motor neuron
- Response by effector
8
Q
Sensory neuron
A
In epithelium; allows us to detect stimuli in the environment; this is the receptor for the pain reflex
9
Q
What do receptors on the dendrites do
A
They are always detecting stimuli, but they don’t always do something about it
10
Q
Resting membrane potential
A
The resting phase of a neuron; when you don’t notice any stimuli from the environment
11
Q
Threshold
A
When a stimulus is strong enough to take it out of resting membrane potential; the point where a stimulus is so strong that it activates a sensory neuron
12
Q
Action potential
A
How neurons communicate; when the stimulus is so strong that the neuron gets to threshold, it will create this
13
Q
Synapse
A
Where a neuron reaches another cell
14
Q
Graded potential
A
Describes a neuron that is analyzing information and deciding what to do about it
15
Q
Motor neuron
A
Activates effectors; activated by CNS
16
Q
What is an example of a motor neuron
A
When moving your hand away from a hot stove, the effector is your muscle
17
Q
Ways to classify reflexes
A
- By development
- By effector
- By complexity
- By integration center
18
Q
Reflexes classified by development
A
- Innate reflex
2. Learned (acquired) reflex
19
Q
Innate reflex
A
Reflexes that you are born with; that you don’t have to learn
20
Q
Learned (acquired) reflex
A
Learned, more complex, motor patterns that are continuously refined
21
Q
Can you suppress a reflex?
A
Yes, you can repress some, but not all, reflexes
22
Q
Reflexes classified by effector
A
- Somatic reflex
2. Visceral reflex
23
Q
Somatic reflex
A
Effector is a response from skeletal muscle
24
Q
Visceral reflex
A
Effector is a response from an organ
25
Reflexes classified by complexity
1. Monosynaptic reflex
| 2. Polysynaptic reflex
26
Monosynaptic reflex
One synapse is being used at a time
27
Example of monosynaptic reflex
Pain reflex
28
Polysynaptic reflex
Multiple synapses being used
29
Pros to monosynaptic refle
They are really fast
30
Cons to monosynaptic reflex
They are unrefined; if you pull away from something painful you could hit your hand on something else
31
Pros to polysynaptic reflex
More refined and complex; if you step on a toy you press down on one foot to keep balance and pull up the other foot
32
Cons to polysynaptic reflex
It is slower than monosynaptic reflex
33
Types of integration centers
1. Cranial
| 2. Spinal
34
What determines which type of integration center you use
The location
35
What does it mean that reflexes are not mutually exclusive?
A reflex can be many different classes (monosynaptic and innate)
36
Reflexes happen...
Before we perceive the stimulus; this allows us to minimize the damage
37
Nervous system branches
1. Central nervous system
| 2. Peripheral nervous system
38
Main function of the CNS
It is the integration center
39
Peripheral nervous system
All the neural tissue that is not in the brain or spinal cord
40
Types of PNS
1. Afferent nervous system
| 2. Efferent nervous system
41
Afferent nervous system
System of neurons that brings sensory information from the body into the CNS
42
Efferent nervous system
Carries motor command information from the CNS to the body
43
Types of Efferent nervous system
1. Somatic nervous system
| 2. Autonomic nervous system
44
Somatic nervous system
Carries efferent/motor commands to skeletal muscle
45
Autonomic nervous system
Controls everything that we move unconsciously
46
Types of autonomic nervous system
1. Sympathetic nervous system
| 2. Parasympathetic nervous system
47
Sympathetic nervous system
"Fight or flight"; increases heart and respiratory rate and shuts down the urinary system and digestive system to save energy
48
Parasympathetic nervous system
"Rest and digest"; stimulates the digestive and urinary systems, decreases heart and respiratory rate
49
Can you have both the sympathetic and parasympathetic system working at the same time?
Yes, there is always a combination of both
50
Cell body
Soma
51
Parts of cell body
1. Nucleus
| 2. Perikaryon
52
Perikaryon
The space around the nucleus; peri=around karyon=nucleus
53
What is found in the perikaryon
All of the organelles that would be found in a normal cell
54
What does the perikaryon lack that other normal cells have, and what does this cause?
Centrioles, which makes neurons unable to divide
55
Nissl bodies
The equivalent of the rough ER in neurons; has ribosomes, which link amino acids and makes proteins, that cover the outside and makes it "rough"; causes the grey color
56
Axon hillock
This creates an action potential if a stimulus is strong enough for a response
57
What direction does the action potential move?
Away from the soma
58
Axolemma
The plasma membrane of the axon
59
Action potential
An electrical current
60
Synaptic terminal
The end of the telodendria; where the neuron communicates with another cell
61
Telodendria
The branches of the axon
62
Synaptic cleft/Synapse
The small gap between the synaptic terminal and the next tell
63
How does the neuron communicate with the next cell?
Inside of the synaptic vesicles there are neurotransmitters; the neuron uses exocytosis to dump the neurotransmitters into the synapse/synaptic cleft
64
What do the neurotransmitters do?
They tell the next cell what to do
65
Types of neurons
1. Anaxonic neuron
2. Bipolar neuron
3. Unipolar neuron
4. Multipolar neuron
66
Anaxonic neuron
Dendrites and axons look the same; the only neuron that is only in the CNS; they help serve as integration centers
67
Bipolar neuron
Afferent; cell body has two distinct extensions (one goes to dendrites, one goes to axon); carries special sensory information like sound, sight, and taste
68
Unipolar neuron
Afferent; cell body with one extension that splits; carries sensory information for everything besides special sensory information like somatic and visceral information
69
Multipolar neuron
Efferent; multiple extensions; carries motor commands from the CNS to the body
70
Membrane potential
An electrical charge; the charge on the inside of the membrane RELATIVE to the charge on the outside
71
What is the mV for resting potential?
-70 mV
72
What things contribute to the negative charge
1. Leak channels
2. Sodium-potassium pump
3. Intracellular proteins
73
Leak channel
Allows for the facilitated diffusion of sodium and potassium ions
74
Where are there more sodium ion?
Outside the membrane
75
Where are there more potassium ions?
Inside the membrane
76
Sodium and potassium have ____ charges
Positive
77
Potassium leaks ____, sodium leaks ____
Out; in
78
Does sodium or potassium leak faster?
Potassium leaks out faster than sodium leaks in
79
Potassium leaking out faster than sodium leaking in causes what
This lowers the charge inside the cell making it more negative
80
Sodium-potassium pump
Active transport; moves sodium out and potassium in; uses energy because it moves things against the gradient
81
Does sodium or potassium move in/out more?
More sodium is moving out than potassium is moving in
82
Intracellular proteins
Located right on the inside of the membrane; negative charge; makes the inside more negative than the outside
83
What causes a membrane potential to leave resting membrane potential?
A stimulus
84
What does a stimulus do to the resting membrane potential?
Either:
1. Makes it more positive
2. Makes it more negative
85
Graded potential
A stimulus that acts on a neuron at rest; a deviation from the resting membrane potential (more + or more -)
86
Types of graded potentials
1. Depolarizing graded potential
| 2. Hyperpolarizing graded potential
87
Depolarizing graded potential
A deviation that makes membrane potential more positive/more like the outside
88
Depolarizing graded potential is also called
Excitatory post-synaptic potential (EPSP)
89
Hyperpolarizing graded potential
A deviation that makes membrane potential more negative/less like the outside
90
Hyperpolarizing graded potential is also called
Inhibitory post-synaptic potential (IPSP)
91
O mV would mean
It is the same on the inside and outside
92
Threshold (membrane potential)
A membrane potential that is between -55 to -50 mV; A certain charge that causes a neuron to fire an action potential
93
EPSP gets you
Closer to threshold
94
IPSP moves it
Further from threshold to silence a neuron
95
Gated channels
At rest, are typically closed
96
Types of gated channels
1. Chemically gated channel
| 2. Mechanically gated channel
97
Chemically gated channel
A chemical stimulus caused it to open
98
Mechanically gated channel
Mechanical pressure (being touched) caused it to open
99
What do gated channels allow?
These allow ions to move through the membrane
100
Gated channels can either be
1. Potassium channels
| 2. Sodium channel
101
If a chemical produced a EPSP it would be
A sodium channel because sodium moves from the outside in, down its gradient
102
What happens in gated channels
They carry out graded potentials; chemical binds to the gated channels, moves in, then is diffused across the membrane
103
How can you tell what kind of gated channel it is?
Look at which way the ions are moving, if they are moving in, it is sodium; if they are moving out, it is potassium
104
What do the sodium-potassium pumps do?
It moves sodium back out to get back to resting membrane potential
105
What is the graded potential "battle"?
EPSP is trying to bring sodium in and reach threshold while the sodium-potassium pumps are trying to pump sodium out and get away from threshold and back to resting membrane potential
106
How do you reach threshold?
There has to be more sodium coming in than the sodium-potassium pump can push back out
107
1 EPSP only changes the membrane potential by
About .5 mV
108
Summation
Adding more than 1 graded potential together; used to get to threshold
109
Types of summation
1. Temporal summation
| 2. Spatial summation
110
Temporal summation
When we summate graded potentials from a single synapse
111
Explain temporal summation
One telodendrian synapses with another neuron. An action potential is sent through the telodendrian and neurotransmitters are sent through the synapse; happens one after another faster than the sodium-potassium pump can push out
112
Can you summate EPSP and IPSP at the same time in temporal summation?
No, you can only summate EPSP OR IPSP, not both at the same time; Because one synapse can only send one type of graded potential (EPSP or IPSP) and they would just cancel each other out
113
Spatial summation
When we summate graded potentials from multiple synapses; the sodium mixes; the synapses must be close together
114
What does summation do for graded potentials
Graded potentials are weak by themselves, so we have to summate them to reach threshold
115
How do we differentiate between different action potentials?
By the way that our neurons are wired; the action potentials get sent to different places in our brain
116
What determines different sensations/the strength of the signal?
The number of action potentials that are being generated
117
Volted-gated channel
A membrane potential (mV) causes it to open or close; has two gates: activation gate on outside of cell, inactivation gate on inside of cell
118
What happens to a volted-gated channel once you reach threshold?
The gates open and allows sodium to rush through until the membrane potential reaches 30 mV
119
When does the inactivation gate close?
When the membrane potential reaches 30 and stays closed until the neuron goes back to resting membrane potential
120
What happens once the membrane reaches -70mV (volted-gated channel)?
The inactivation gate opens and the activation gate closes
121
Describe the graph and what happens when the membrane potential reaches threshold
When the membrane potential reaches threshold, action potential begins and the membrane potential goes more and more positive, then it goes back to resting membrane potential
122
What can we tell from this graph?
1. In this graph there is an EPSP that depolarizes
| 2. It must be summated because one EPSP will move it only about .5 mV
123
What happens when the cell reaches threshold?
Volted gated sodium channels open
124
Once the membrane reaches 30+ what happens?
1. The inactivation gate of the volted gated sodium channel closes
2. Volted gated potassium channels open and potassium rushed out
125
What happens at about -70mV?
Volted gated potassium channels are closed
126
What is happening at 4 on the graph? (mV moves below -70mV briefly after the action potential comes back down and then moves back to resting membrane potential)
The potassium channels take a long time to close, so they start closing down early causing it to lose a little too much potassium and it hyperpolarizes, or becomes more negative
127
What protein repolarizes and gets the cell back to rest?
Sodium-potassium pump
128
Why do we need an IPSP?
To move things away from threshold so that another neuron can have more accurate information (mosquito example)
129
How does an action potential move down the axon?
One section depolarizes, reaches threshold, fires an action potential, and volted gated sodium channels open causing sodium to rush in, diffuse, and cause the next section to reach threshold
130
Propagation
How an action potential moves from the cell body to the synapse
131
Types of propagation
1. Continuous propagation
| 2. Saltatory propagation
132
Continuous propagation
When every single part of the axon reaches threshold; not very fast
133
Saltatory propagation
Skips through the axon and doesn’t touch every part of the axon; fastest way
134
What makes saltatory propagation possible?
Myelin
135
What cell types produce myelin?
1. Shwann cell
| 2. Oligodendrocyte
136
What does myelin do for an axon?
It prevents any ions from moving across the membrane so there is no movement of sodium or potassium; it wraps around the axon in layers
137
Node of Ranvier
The exposed axon that is not covered by myelin
138
Internodes
Myelinated regions between the nodes that is covered in myelin
139
How do action potentials move?
They are unidirectional, they only move towards the synapse and away from the cell body
140
Absolute refractory period
The period of time from when the volted gated sodium channels open until they close and are inactivated
141
Why is it impossible to fire an action potential during the absolute refractory period?
Because the volted gated sodium channels are either being used or inactivated
142
Relative refractory period
The period of time when the membrane is hyperpolarized and below resting membrane potential
143
Why can you fire an action potential during the relative refractory period?
Because the volted gated sodium channels are reset and can be used again, but the stimulus has to be stronger than normal because the membrane potential is further than usual from threshold
144
What happens when the sodium diffuses, going both up and down the membrane, and it goes backwards?
The membrane is in absolute refractory period and can't fire another action potential
145
What is the importance of refractory periods?
They keep action potentials moving in one direction
146
What determines the speed of an action potential?
1. If it is myelinated or not
| 2. The diameter of the axon/neuron
147
How does the diameter of the axon/neuron affect the speed of an action potential?
Local currents can move quicker and sodium diffuses faster
148
Fastest type of neuron
Myelinated with a large diameter
149
Slowest type of neuron
Unmyelinated with a small diameter
150
Presynaptic neuron
The neuron that is giving the neurotransmitters
151
Postsynaptic neuron
The neuron that is receiving the neurotransmitters
152
Cholinergic
Secretes Acetylcholine
153
Neuromuscular junction
A neuron forms a synapse onto a muscle cell
154
What happens when the action potential reaches the synapse?
It opens a volted gated calcium channel, which is found at the end of the synapse that opens in response to the action potential
155
Calcium has the same concentration gradient as what and what does that mean
Sodium; this means that calcium floods into the cell, down its gradient
156
What is the result of calcium flooding into the cell?
It causes the exocytosis of the neurotransmitter into the synapse
157
What happens after the neurotransmitters are pushed into the synapse?
Acetylcholine or other neurotransmitters binds to a receptor on the postsynaptic neuron and sodium moves in
158
What kind of receptor are they?
Chemically gated sodium channels
159
What does the sodium do to the next cell?
It makes it start an EPSP, but that doesn't mean that it will reach threshold
160
Reuptake
Since neurotransmitters need to be removed from the synapse, this is the process where the presynaptic neuron sucks the neurotransmitters back up
161
Neuroglia
All other cells besides neurons in neural tissue
162
Types of neuroglia in the CNS
1. Astrocyte
2. Oligodendrocyte
3. Microglia
163
Astrocyte
Has arm like structures and covers capillaries; they determine what from the blood gets in and doesn’t get in to the CNS
164
Oligodendrocyte
Makes myelin, but only in the CNS
165
Microglia
Important for immunity in the CNS
166
Types of neuroglia in the PNS
1. Schwann cells
| 2. Satellite cells
167
Schwann cells
Make myelin in the PNS
168
Satellite cells
Important for immunity in the PNS
