the nervous system Flashcards
(120 cards)
1
Q
what are the two major divisions of the nervous system?
A
Central Nervous System (CNS) and Peripheral Nervous system (PNS)
2
Q
what are nerve cells called?
A
neurons
3
Q
what does the central nervous system include?
A
the brain and spinal cord
4
Q
what does the peripheral nervous system contain?
A
everything else (that’s not brain and spinal cord)
5
Q
what are the parts of a neuron?
A
dendrites, cell body, axon, myelin sheath, schwann cell, nodes of ranvier, synaptic endings
6
Q
what is a dendrite’s function?
A
dendrites have lost of surface area to pick up nerve impulses and conduct the impulse towards the cell body
7
Q
what is the cell body?
A
the metabolic center of the cell
8
Q
what does the cell body do?
A
metabolic reactions occur there (ie: cellular respiration, protein synthesis, lipid synthesis)
9
Q
what is the function of an axon?
A
conducts nerve impulses away from the cell body
10
Q
what is the myelin sheath and what is the function of it?
A
it is made of lipids and wraps around the axon and cell body to insulate it.
11
Q
what is a schwann cell?
A
produces the myelin sheath and has tightly packed spirals of cell membranes that form layers of the myelin
12
Q
what are the nodes of ranvier?
A
gaps in the myelin where the axon is not insulated and allows more rapid nerve conduction along the axon
13
Q
what are synaptic endings?
A
the end of the axon where vesicles containing neurotransmitters are located
14
Q
what are neurons?
A
specialized nerve cells that carry nerve impulses
15
Q
what are the three types of neurons?
A
- sensory
- motor
- interneuron
16
Q
what is another name for a sensory neuron?
A
afferent neuron
17
Q
what is another name for a motor neuron?
A
efferent neuron
18
Q
what is another name for an interneuron?
A
association neuron or connector neuron
19
Q
what does a sensory neuron do?
A
takes messages from sense organs to CNS
20
Q
what does a motor neuron do?
A
takes messages from the CNS to a muscle fibre or gland
21
Q
what does an interneuron do?
A
conveys “messages” between parts of the nervous system
22
Q
what are the characteristics of a sensory neuron?
A
long dendrites and short axon
23
Q
what are the characteristics of a motor neuron?
A
short dendrites and long axon
24
Q
what are the characteristics of an interneuron
A
interneurons are completely contained within CNS. dendrites and axons can be long or short
25
what is nerve conduction?
an electrical impulse that moves in one direction along the length of a nerve fiber
26
what changes occur with nerve conduction?
voltage and concentrations of certain ions
27
what can be used to measure potential differences in voltages?
an oscilloscope
28
what are the three phases of nerve impulse conduction
1. resting potential
2. action potential
3. refractory period
29
what is resting potential?
the potential difference across the membrane of the axon when it is NOT conducting an impulse
30
what is resting potential equal to?
-70mv
31
why is resting potential negative?
the presence of large organic negative ions (proteins) in the axoplasm
32
what is the axoplasm
cytoplasm inside the axon
33
during resting potential where are sodium ions more concentrated?
the outside of the membrane
34
during resting potential where are potassium ions more concentrated?
the inside of the axon
35
how is the uneven distribution of Na+ and K+ ions maintained?
active transport across sodium/potassium pumps
36
what is action potential?
when a nerve is stimulated by electric shock, ph change, or mechanical stimulation (touch, temp) and a nerve impulse is generated (the impulse is called action potential)
37
during the upswing in action potential the -70mv becomes what number?
+40mv
38
what is the upswing?
the membrane becomes permeable to Na+ ions and sodium moves from outside to inside.
39
what is it called when when sodium ions move inside and make the axon positive?
depolarization
40
during the upswing why does the membrane become permeable to sodium ions
sodium channels open
41
what is the downswing in action potential?
the membrane become permeable to K+ ions and potassium moves from inside to outside of axon
42
what is it called when potassium moves from inside to outside and makes the axon negative again?
repolarization
43
why does the membrane become permeable to K+ during the downswing?
potassium channels open
44
what is the refractory period?
in between nerve impulses/transmissions when K+ and Na+ ions are returned to their original postition
45
what does the refractory period require?
ATP and a carrier protein
46
what gives nerves their white and shiny appearance?
myelin
47
what is the speed of transmission in myelinated fibers?
200m/s
48
what is the speed of transmission in non-myelinated fibers?
0.5m/s
49
why is transmission faster with a myelinated fiber?
nerve impulses “jump” from node to node in myelinated fibers and must de and repolarize each point along the fiber in non-myelinated fibers
50
what are advantages of myelinated fibers over non myelinated?
- think faster
- respond faster
- move faster
51
what is at the end of an axon?
synaptic endings
52
what do synaptic endings do?
release neurotransmitters to affect the potential of the next neurons
53
what is a synapse?
the region between the end of an axon and the cell body or dendrite it is attached to
54
what are synaptic endings?
swollen terminal knobs on the ends of axon terminal branches
55
what is a presynaptic membrane?
the membrane of the synaptic ending
56
what is a postsynaptic membrane?
the membrane of the next neuron just beyond the axons synaptic membrane
57
what is a synaptic cleft?
the space between the pre and post membranes
58
what are neurotransmitter substances?
chemicals that transmit the nerve impulses across a synaptic cleft
59
what are excitatory transmitters?
they make post-synaptic membranes more permeable to Na+
60
what are some examples of excitatory transmitters?
epinephrine, dopamine, glutamate
61
what are inhibitory transmitters?
make post-synaptic membranes less permeable to Na+
62
what are examples of inhibitory transmitters?
GABA, serotonin, glycine
63
what do synaptic vesicles do?
contain the neurotransmitters near the surface of synaptic endings
64
what are neurotransmitters?
small molecules. they can be single amino acids, short chains of aa, or derivatives of protein.
65
what do neurotransmitters do?
take nerve impulses across synapses
66
what does an excitatory message do?
it tells a neuron to fire
67
what does an inhibitory message do?
tells a neuron not to fire
68
what does the PNS focus on?
voluntary and involuntary control
69
The Peripheral Nervous System consists of nerves that contain only _____ dendrites and/or axons
long
70
neuron cell bodies are only found where?
brain, spinal cord, ganglia
71
what are ganglia?
collections of cell bodies in the PNS
72
what are the three types of nerves?
1. sensory nerves
2. motor nerves
3. mixed nerves
73
what do sensory nerves contain?
long dendrites of sensory neurons
74
what do motor nerves contain?
only the long axons of motor neurons
75
what do mixed nerves contain?
contain both the long dendrites of sensory neurons and the long axons of motor neurons
76
how many pairs of cranial nerves do humans have attached to the brain?
12
77
how many pairs of spinal nerves do humans have?
31
78
where do the roots of mixed nerves lie within?
the vertebral column
79
the dorsal root can be identified by what?
the presence of an enlargement called the dorsal root ganglion
80
what does the dorsal root ganglion contain?
cell bodies of sensory neurons
81
what does the ventral root contain?
axons of motor neurons
82
where to the two roots (dorsal and ventral) meet?
just before the spinal nerve leaves the vertebral column
83
what are two branches of the peripheral nervous system?
autonomic and somatic
84
what are reflexes?
automatic, involuntary responses to changes occurring inside or outside the body
85
what is the main functional unit of the nervous system?
the reflex arc
86
what are the steps to a reflex action?
1. receptor stimulated
2. sensory neuron carries impulse (via dorsal root ganglion)
3. sensory neuron synapses with interneuron
4. interneuron synapses with motor neuron
5. motor neuron carries impulse
87
what are two branches of the autonomic nervous system?
sympathetic and parasympathetic
88
which of the PNS branches is voluntary movement
somatic
89
which of the PNS branches is involuntary movement?
autonomic
90
what is the main thing the sympathetic nervous system controls?
fight or flight response
91
the parasympathetic nervous system gives off a ____ state?
relaxed
92
the sympathetic and parasympathetic nervous systems connect to _____ organs and have the _____ effects?
the same, opposite
93
how many motor neurons does the sympathetic and parasympathetic system use for each impulse?
2
94
how many ganglions does the sympathetic and parasympathetic system use for each impulse?
1
95
what neurotransmitter is connected to the sympathetic NS?
noradrenalin/norepinephrine
96
what neurotransmitter is connected to the parasympathetic NS?
aretylcholine
97
what are the 3 protective membranes of the CNS called?
meninges
98
what are the three meninges called?
dura mater, arachnoid, pia mater
99
what are the spaces between meninges filled with for cushioning and protection?
spinal fluid (cerebro)
100
what “nickname” does the spinal cord have?
superhighway of the nervous system
101
what is grey matter?
cell bodies, where synapses occur and interneurons are located
102
what is white matter?
myelinated nerve tracts
103
how much does the brain weigh?
3 pounds (approx)
104
what are the 4 lobes of the cerebral hemispheres?
frontal, parietal, temporal, occipital
105
what are the sections of the hindbrain?
medulla oblongata
| cerebellum
106
what are the sections of the forebrain?
thalamus
hypothalamus
corpus callosum
107
what is the medulla oblongata?
the “brain stem”
| controls heart rate, breathing, blood pressure, and reflex reactions
108
what is the cerebellum?
controls balance and complex muscle movement. it is responsible for maintaining normal muscle tone and pressure
109
what is the midbrain?
central relay station between the fore and hindbrain and medulla oblongata
110
what is the thalamus?
receives sensory info from all parts of the body and channels them to the cerebrum
111
what is the hypothalamus?
regulates homeostasis and controls pituitary gland
112
what is the corpus callosum?
horizontal connecting piece between the two hemispheres of the brain. it transmits impulses between them
113
which side of the brain is more creative/ visual?
right
114
which side of the brain contains speech?
left
115
what is the conscious brain?
the cerebrum
116
what is the cerebrum?
the largest and most highly developed portion of the brain. intellect, learning, memory, and sensations are formed here.
117
what does the frontal lobe control?
thinking, problem solving, movement, moving mouth/tongue to speak
118
what does the parietal lobe control?
primary senses (touch, temp, pain) and understanding speech
119
what does the temporal lobe control?
hearing, smelling, memory of visual scenes, music, complex sensory patterns
120
what does the occipital lobe control?
vision, combining visual experiences with other sensory experiences
