NERVOUS SYSTEM UNIT REVIEW Flashcards
1
Q
Nervous system functions
A
Responsible for coordination of movement and to respond to environmental stimuli, intelligence, self-awareness, thought, and emotion
2
Q
What are nerve cells composed of
A
Neurons
3
Q
Neurons
A
Specialized to carry nerve impulses
4
Q
What does it mean when the two nervous systems are ARBITRARY
A
Meaning that they both work together and are connected to one another
5
Q
Two major divisions of nervous system:
A
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
6
Q
What is the central nervous system associated with
A
Brain and spinal cord
7
Q
What is the peripheral nervous system associated with
A
The rest of the nervous system
8
Q
Parts of a neuron (7):
A
- Dendrites
- Cell body
- Axon
- Myelin sheath
- Schwann cell
- Nodes of Ranvier
- Synaptic endings
9
Q
Dendrites
A
Contains great surface area to pick up nerve impulse and conduct it towards cell body
10
Q
Cell body
A
Metabolic centre of cell
11
Q
What type of reactions occur in cell body
A
Cellular respiration and protein/lipid synthesis
12
Q
Axon
A
Conducts nerve impulses away from cell body
13
Q
Myelin sheath
A
Made of lipids and wraps around axon to insulate
14
Q
Schwann cells
A
Produces myelin sheath. It contains tightly packed spirals of cell membrane
15
Q
Nodes of Ranvier
A
Gaps in the myelin. It allows more rapid nerve conduction along axon
16
Q
Synaptic endings
A
End of axon. Vesicles containing neurotransmitters are located here
17
Q
3 types of neurons:
A
- Sensory neuron
- Motor neuron
- Interneuron
18
Q
Sensory neuron
A
Takes a message from a sense organ to CNS
19
Q
Another name for sensory neuron
A
Afferent neuron
20
Q
What do sensory neurons contain
A
Long dendrites and short axon
21
Q
Motor neurons
A
Takes message away from CNS to muscle fiber or gland
22
Q
Another name for motor neuron
A
Efferent neuron
23
Q
What do motor neurons contain
A
Short dendrites and long axon
24
Q
Interneuron
A
Completely contained within CNS. Conveys messages between parts of the system
25
Another name for interneuron
Association neuron/connector neuron
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What do interneurons contain
Long or short dendrites and axons (size varies)
27
Giant squid axon
Very large axon that controls part of the water jet propulsion system in squid to rapidly activate muscles of squid mantle
28
Nerve conduction is an _____
Nerve conduction is an ELECTRICLE IMPULSE
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Direction of electrical impulse
One direction along length of nerve fiber
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What do electrical impulses contain
Changes in voltage, as well as concentration of certain ions
31
Oscilloscope
Voltmeter that shows graph of voltage changes to measure potential differences
32
3 distinct phases of nerve impulse conduction/propagation:
- Resting potential
- Action potential
- Refractory period
33
Resting potential
Potential difference across the membrane of axon when it is not conducting an impulse
34
Voltage across membrane of axon at resting
-65v
35
Reasonings of negative polarity of resting
Due to presence of large organic negative ions (proteins) in the axoplasm
36
Na and K concentrations at resting
More Na ions on the outside of axon compared to inside, and more K ions on the inside compared to outside
37
How is the uneven distribution of Na and K maintained by
Active transport across Na+/K+ pump which operate whenever the neuron is not conducting an impulse
38
How are nerves in action potential stimulated
Through electric shock, pH change, or mechanical stimulation
39
Action potential
When nerve impulse is generated and a change in voltage occurs
40
Depolarization
When during UPSWING (-65mV to +40mV) the membrane becomes permeable due to Na channels opening and Na ions move from outside to inside of axon. It is called depolarization because the inside of axon becomes positive
41
Repolarization
When during DOWNSWING (+40mV to -70mV) due to K channels opening and K moves inside axon. It is called repolarization because the inside of axon becomes negative again
42
Refractory period
In between nerve impulses/transmissions, K ions are returned to inside of axon and Na to the outside back to original
43
How is transportation of refractory period achieved
Using active transport with carrier proteins
44
Step 1 of nerve impulse conduction/propagation
Sodium moves in; Sodium channels open and Na+ ions diffuse INTO axon
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Step 2 of nerve impulse conduction/propagation
Depolarization; Inside of axon of specific region is now positive
46
Step 3 of nerve impulse conduction/propagation
Na+ channels close and K+ opens; Potassium channels open and K+ ions diffuse OUT of axon
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Step 4 of nerve impulse conduction/propagation
Repolarization; Movement of K+ ions counters depolarization. The voltage difference across membrane returns to resting potential
48
Step 5 of nerve impulse conduction/propagation
Recovery period; Na+ and K+ actively transported back across membrane until concentrations are equally distributed as before impulse was sent (ATP STAGE USING CARRIER PROTEINS)
49
Step 6 of nerve impulse conduction/propagation
Depolarization of adjacent part of axon; Sodium channels open and Na+ ions diffuse into axon
50
Which stage uses ATP and why
Step 5 (recovery period) uses ATP for carrier proteins
51
Are nerve impulses rapid or slow
Rapid
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What allows nerve impulses travel so fast
Myelin sheath serves as an electrical insulator to allow nerve impulses to travel fast and maintain high speed communication between nerve cells
53
What is myelin sheath formed of
Formed by tightly packed spirals of cell membrane of Schwann Cell
54
What are the interruptions or gaps of the myelin sheath called
Nodes of Ranvier
55
Myelin physical characteristics
White and shiny
56
Speed of transmission in myelinated fibres
200m/s
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Speed of transmission in non-myelinated fibers
0.5m/s
58
Why are nerve impulses faster with myelinated fibers compared to non-myelinated fibers
Because the nerve impulses jumps from node to node in myelinated fibers. However, with non-myelinated fibers, the nerve impulse must depolarize and repolarize each point along the nerve fibre
59
Advantages of an organism with myelinated fibers (2):
- Respond to stimulus faster
| - Think faster
60
Synaptic ending
Specialized regions at the ends of axons. They are swollen terminal knobs on the ends of axon terminal branches
61
Why are transmissions across a synapse one way
Because only the ends of axons have synaptic vesicles that can release neurotransmitters to affect the potential of the next neurons
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Synapse
Region between end of an axon and the cell body/dendrite to which it is attached
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Presynaptic membrane
Membrane of synaptic ending
64
Postsynaptic membrane
Membrane of the next neuron beyond axon’s synaptic membrane
65
Synaptic cleft
Space between the pre and past synaptic membranes
66
Synaptic vesicles
Contains neurotransmitters contained near surface of synaptic endings
67
Neurotransmitter substances
Chemicals that transmit the nerve impulses across a synaptic cleft
68
2 types of neurotransmitter substances:
- Excitatory transmitters
| - Inhibitory transmitters
69
Excitatory transmitters and examples
Make post synaptic membrane more permeable to Na+. Eg. Adrenalin, dopamine, glutamine
70
Inhibitory transmitters and examples
Make post synaptic membrane less permeable to Na+. Eg. GABA (Gamma Amino Butyric Acid), glycine, serotonin
71
Sequence of events during synapse (8):
- Nerve impulse travels along axon and reaches synaptic ending
- Ca+ flows into ending through channel proteins
- Ca+ ions cause contractile proteins to pull synaptic vesicles to inner surface of presynaptic membrane
- Vesicle fuses with presynaptic ending and releases NT to synapse
- NT diffuse across synaptic cleft to receptor on postsynaptic membrane
- NT binding to specific receptors can open the ion channels
- Ion flux changes voltage of postsynaptic membrane and moves membrane voltage closer to threshold value required for action potential
- NT is degraded to prevent them from continually acting on postsynaptic membrane
72
How are neurotransmitters degraded (2):
- Enzymes such as acetylcholinesterase breaks down acetylcholine
- Synaptic ending reabsorbs the NT through endocytosis
73
Monoamine oxidase
Breaks down noradrenaline after absorbed
74
Neurotransmitters
Takes nerve impulses across synapses. They are small molecules
75
Examples of NT
Single amino acids, short chains of amino acids, or derivatives of protein
76
How is proper brain and nervous system function maintained
Through proper balance of excitatory and inhibitory synaptic transmitters
77
What does it mean when a single neuron may receive information from thousands of neighbouring neuron through thousands of synapse
Means that some of the messages can be excitatory (telling neurons to fire), while others may be inhibitory (telling neurons not to fire)
78
5 actions of drugs at synapse:
- Stimulates release of NT
- Blocks release of NT
- Combines with NT preventing its breakdown
- Mimics NT
- Blocks receptor so NT can’t be received
79
Drugs
Promotes or decreases action of NT by stimulating or inhibiting the actions of excitatory/inhibitory transmitters
80
Stimulants
Enhance excitatory transmitters or block action of inhibitory transmitters
81
Depressants
Enhance action of inhibitory transmitters or block action of excitatory transmitters
82
What does the peripheral nervous system consist of and why
Nerves that only contain long dendrites and/or long axons. This is because neuron cell bodies are only found in the brain, spinal cord, and ganglia
83
Ganglia
Collections of cell bodies within PNS
84
3 types of nerves:
- Sensory nerves
- Motor nerves
- Mixed nerves
85
What do sensory nerves contain
Long dendrites of sensory neurons
86
What do motor nerves contain
Long axons of motor neurons
87
What do mixed nerves contain
Both long dendrites of sensory neurons and long axons of motor neurons
88
Cranial nerves (3):
- Part of PNS
- All 3 types of nerves
- Head, neck, face, EXCEPT vagus nerve
89
How many pairs of cranial nerves are attached to brain
12 pairs
90
Spinal nerves (2):
- Mixed nerves
| - Dorsal root and ventral root join just before spinal nerve leaves vertebral column
91
How many pairs of spinal nerves do humans have
31 pairs
92
Dorsal root
Identified by presence of an enlargement called dorsal root ganglion which contains cell bodies of sensory neurons whose dendrites conduct impulses towards spinal cord
93
Ventral root
Each spinal nerve contains axons of motor neurons that conduct impulses away from cord
94
Somatic nervous system
Includes all nerves that serve the musculoskeletal system and the exterior sense organs
95
Reflexes
Involuntary responses to changes occurring inside or outside the body
96
Reflex arc
Main functional unit of nervous system
97
5 steps to reflex action:
- Receptor is stimulated (temp, pain)
- Sensory neuron carries impulse through dorsal root ganglion to spinal cord
- Sensory neuron synapses with interneuron in gray matter of spinal cord
- Interneuron synapses with motor neuron
- Motor neuron carries impulse through ventral root to muscle/gland
98
Gray matter (3):
- Where synapses occur
- Interneurons located here
- Has 6 million cell bodies
99
White matter
Myelinated nerve tracts (bundle of axons)
100
Why do doctors test reflex with reflex hammer
To make sure your nerve-spinal cord pathway is functional
101
What components make up the autonomic nervous system
Divided into sympathetic and parasympathetic nervous system. The two systems connect to same organs but have opposite effects
102
Sympathetic and parasympathetic nervous system functions in the autonomic nervous system
Functions automatically on internal organs and utilizes two motor neurons and one ganglion for each nerve impulse
103
Sympathetic nervous system significance
Significant for emergency situations because it triggers your fight or flight
104
What are neurotransmitters released by in sympathetic nervous system
post-ganglionic axon
105
Where do post-ganglionic fibers of sympathetic nervous system arise in sympathetic nervous system
From middle part (Thoracic lumbar) of spinal cord
106
Long or short for preganglionic fiber and postganglionic fiber in sympathetic nervous system
Preganglionic is short and postganglionic is long
107
NT for sympathetic nervous system
Noreadrenaline
108
Parasympathetic nervous system function
Promotes all internal responses associated with a relaxed state
109
NT for parasympathetic nervous system
Acetylcholine
110
What are neurotransmitters released by in parasympathetic nervous system
Post-ganglionic axon
111
Where do post-ganglionic fibers of parasympathetic nervous system arise
Arise from upper and lower part of spinal cord (cranial and sacral nerves)
112
Long or short for preganglionic fiber and postganglionic in parasympathetic nervous system
Pre-ganglionic fiber is long and post-ganglionic fiber is short because the ganglia lies near or within organ
113
Weight of brain
3lbs
114
What makes up the central nervous system
Brain and spinal cord
115
Name of the protective membranes of CNS
Meninges
116
3 protective membranes of CNS
Dura mater, arachnoid, pia mater
117
What are the spaces in between meninges filled with and why
Cerebral spinal fluid for cushioning and protection
118
Facts about the brain
We had the maximum amount of neurons when we are born and thousands are lost daily
119
What does hindbrain refer to
Medulla oblongata
120
Where is medulla oblongata located
Closest to spinal cord
121
What does medulla oblongata control (8):
- Heart beat
- Breathing
- Blood pressure
- Coughing
- Sneezing
- Vomitting
- Hiccuping
- Swallowing
122
What does the cerebellum control
Balance and complex skeletal movement. It is responsible for painting normal muscle tone and posture
123
Where does the cerebellum receive sensory information from
Inner ear and medulla oblongata
124
Midbrain is an intersection of
Intersection of the forebrain, hindbrain and medulla oblongata
125
What does the forebrain refer to
Thalamus
126
Where does the thalamus receive sensory information from
All parts of the body. It receives all impulses except smell and sends them to appropriate regions of cortex
127
ARAS
The reticular activating system that sorts out incoming stimuli and passes them to cerebrum to information that requires immediate attention. So essentially it lets you ignore certain input
128
Where does the ARAS extend from
Medulla oblongata to the thalamus
129
Hypothalamus significance
Homeostasis by maintaining internal environment
130
Hypothalamus contains centres for.. (7):
- Hunger
- Thirst
- Body temp
- Water balance
- Blood pressure
- Sex drive
- Sleep
131
What does the hypothalamus control
Pituitary gland which serves as a gland between nervous system and endocrine system
132
Corpus callosum function
Transmits impulses between two cerebral hemispheres. (Right and left side of brain)
133
What does it mean if corpus callous is severed
Means that the two halves of the brain does not communicate with one another normally and will function separately
134
What does the conscious brain refer to
Cerebrum
135
Largest and most prominent portion of brain
Cerebrum
136
Name of outer layer of cerebrum
Cortex
137
What does the cerebrum do
Forms intellect, learning, memory, and sensations
138
What is the cerebrum divided into
Right and left cerebral hemispheres which contains 4 lobes
139
4 lobes of cerebrum:
- Frontal
- Parietal
- Temporal
- Occippital
140
Frontal lobe (4):
Problem solving, concentration, planning, movement of tongue and mouth
141
Parietal lobe (5):
- Touch
- Temp
- Pain
- Pressure
- Understanding speech
142
Temporal lobe (5):
- Hearing
- Smell
- Memory of visual scenes
- Music
- Interpretation of experiences
143
Occipital lobe
Vision
144
Right and left hemisphere of brain function
Right controls left side of body (except smell), and vice versa. An image viewed with the right eye is actually "seen" with then left occipital lobe
145
Left hemisphere of brain is referred to
Logical side
146
Right hemisphere of brain is referred to
Intuitive side
