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Kin 267 (Phys. 1) > Nervous System (Pt. 1) > Flashcards

Nervous System (Pt. 1) Flashcards

1
Q

Q: What makes up nervous tissue?

A

A: Neurons and neuroglia.

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2
Q

Q: What is a nerve?

A

A: Bundles of axons, connective tissue, and blood vessels located outside CNS & PNS.

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3
Q

Q: What percentage of total body weight is the nervous system?

A

A: About 3% (2 kg or 4.5 lb).

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4
Q

Q: What are the two main parts of the nervous system?

A

A: Central nervous system (CNS) and peripheral nervous system (PNS).

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5
Q

Q: What are the two components of the CNS?

A

A: Brain and spinal cord.

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6
Q

Q: What are the two divisions of the PNS?

A

A: Sensory (Afferent) Division and Motor (Efferent) Division.

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7
Q

Q: What are the two branches of the Autonomic Nervous System?

A

A: Sympathetic Division (“fight-or-flight”) and Parasympathetic Division (“rest-and-digest”).

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8
Q

Q: What is the function of sensory receptors?

A

A: To monitor changes in the external and internal environment.

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9
Q

Q: What are enteric plexuses?

A

A: Networks of neurons in the digestive tract that regulate smooth muscle and gland functions.

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10
Q

Q: What is the key feature of neurons?

A

A: The ability to quickly transmit signals over both short and long distances, enabling rapid response to stimuli.

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11
Q

Q: What are the main characteristics of neurons?

A

A: They are specialized for sensing, thinking, memory, control; cannot divide; are electrically excitable; and respond to stimuli.

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12
Q

Q: What is a nerve impulse?

A

A: An electrical signal that travels along neuron membranes, caused by sodium and potassium ion movement.

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13
Q

Q: What is unique about nerve impulse strength?

A

A: They move at constant strength.

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14
Q

Q: What makes neurons some of the longest cells in the human body?

A

A: They can stretch from the spinal cord to toes or from foot to brain.

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15
Q

Q: Can neurons reproduce?

A

A: No, neurons cannot divide or reproduce.

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16
Q

Q: What are the two main cell types in the nervous system?

A

A: Neurons and Neuroglia.

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17
Q

Q: What are the main components found in the cell body (soma)?

A

A: contains nucleus and typical cell components

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18
Q

Q: What is a ganglion?

A

A: A cluster of multiple cell bodies located outside the CNS.

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19
Q

Q: What indicates aging in neurons?

A

A: The presence of lipofuscin pigment.

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20
Q

Q: What are dendrites and their function?

A

A: They are the receiving portion of the neuron, with branched, tree-like structures containing receptor sites for neurotransmitters.

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21
Q

Q: What is unique about dendritic structures?

A

A: They have numerous receptor sites (dendritic spines).

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22
Q

Q: What is the axon’s main function?

A

A: To propagate nerve impulses toward other neurons, muscle fibers, or gland cells.

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23
Q

Q: Where do nerve impulses begin in a neuron?

A

A: At the axon hillock’s initial segment (trigger zone).

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24
Q

Q: What important structure is NOT found in axons?

A

A: Rough endoplasmic reticulum (no protein synthesis occurs in axons).

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25
Q

Q: What are axon collaterals?

A

A: Side branches that extend from the main axon.

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26
Q

Q: How does an axon end?

A

A: It terminates in axon terminals or telodendrion for communication.

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27
Q

Contains synaptic vesicles that contain neurotransmitters (relays the action potential):

A

axon terminal

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28
Q

Site of communication between 2 neurons or a neuron and effector cell (muscle, gland)

A

Synapse

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29
Q

Q: What are the two forms of axon terminal endings?

A

A: Synaptic end bulbs (bulb-shaped swellings) and varicosities (string of swollen bumps).

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30
Q

Q: What are synaptic vesicles?

A

A: Tiny membrane-enclosed sacs that store neurotransmitters.

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31
Q

Q: What are the two possible effects of neurotransmitters?

A

A: Excitatory or inhibitory effects on target cells.

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32
Q

Q: What is fast anterograde transport?

A

A: Movement of materials from cell body to axon terminals at 200-400 mm per day.

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33
Q

Q: What is retrograde transport?

A

A: The return of materials back to the cell body for recycling.

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34
Q

Q: What is a synapse?

A

A: A small gap where two neurons meet or where a neuron connects to a muscle or gland cell.

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35
Q

Q: What are the three types of synapses?

A

A: Neuron-to-neuron, neuron-to-muscle, and neuron-to-gland.

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36
Q

Q: How does signal transmission work at a synapse?

A

A: Presynaptic neuron releases neurotransmitters that travel across the synaptic cleft to the next cell.

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37
Q

Q: What types of cells can neurons form synapses with?

A

A: Other neurons, muscle fibers, and gland cells.

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38
Q

Q: Why are synapses important?

A

A: They enable rapid information transmission and flexible communication between cells for complex body functions.

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39
Q

Q: What are the two main divisions of the nervous system?

A

A: Central Nervous System (CNS) and Peripheral Nervous System (PNS).

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40
Q

Q: What are the two main divisions of the PNS?

A

A: Sensory Division (Afferent) and Motor Division (Efferent).

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41
Q

Q: What are the two types of senses in the Sensory Division?

A

A: Somatic senses (touch, temperature, pain, position) and special senses (vision, hearing, smell, taste, balance).

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42
Q

Q: What are the two branches of the Motor Division?

A

A: Somatic Nervous System and Autonomic Nervous System.

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43
Q

Q: What are the three parts of the Autonomic Nervous System?

A

A: Sympathetic (fight/flight), Parasympathetic (rest/digest), and Enteric (digestive control).

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44
Q

Q: How does the Sensory Division function?

A

A: As an “INPUT” system, bringing information TO the CNS.

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45
Q

Q: How does the Motor Division function?

A

A: As an “OUTPUT” system, sending commands FROM the CNS.

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46
Q

Q: What does the Somatic Nervous System control?

A

A: Voluntary movements of skeletal muscles.

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47
Q

Q: What three types of tissue does the Autonomic System affect?

A

A: Smooth muscle, heart muscle, and glands.

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48
Q

Q: What is the main function of the CNS?

A

A: To process information received from the body.

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49
Q

Conveys messages INTO the CNS

A

Sensory Division (i.e. Afferent)

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50
Q

Conveys messages FROM CNS

A

Motor Division (i.e. Efferent)

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51
Q

Q: What are the three main functions of the nervous system?

A

A: Sensory, integrative, and motor functions.

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52
Q

Q: What is the sensory function?

A

A: To detect changes through sensory receptors, both inside and outside the body.

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53
Q

Q: What is the integrative function?

A

A: To analyze incoming sensory information, store information, and make decisions about appropriate behaviors.

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54
Q

Q: What is the motor function?

A

A: To respond to stimuli via effectors (muscles and glands).

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55
Q

Q: What components are involved in the motor response?

A

A: Muscles and glands (effectors).

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56
Q

Q: Using a cell phone as an example, what represents the sensory function?

A

A: Hearing the phone ring through ear stimulation.

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57
Q

Q: Using a cell phone as an example, what represents the integrative function?

A

A: The brain processing the ring and deciding to answer the call.

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58
Q

Q: Using a cell phone as an example, what represents the motor function?

A

A: Muscles moving to grab and answer the phone.

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59
Q

Q: What happens after sensory receptors detect changes?

A

A: The information travels to the brain and spinal cord through nerves.

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60
Q

Q: What are the three main types of neurons?

A

A: Sensory (afferent) neurons, interneurons (association neurons), and motor (efferent) neurons.

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61
Q

Q: What is the function of sensory neurons?

A

A: To convey information to the CNS when stimuli activate sensory receptors.

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62
Q

Q: What is the function of interneurons?

A

A: To process sensory information and elicit motor responses within the CNS.

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63
Q

Q: What is the function of motor neurons?

A

A: To convey information from the CNS to muscles and glands.

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64
Q

Q: Where are interneurons located?

A

A: In the CNS, between sensory and motor neurons.

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65
Q

Q: What type of structure do most sensory neurons have?

A

A: Unipolar structure.

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66
Q

Q: What type of structure do most motor neurons and interneurons have?

A

A: Multipolar structure.

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67
Q

Q: How do motor neurons transmit signals?

A

A: Through cranial or spinal nerves.

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68
Q

Q: What happens when a sensory receptor is activated?

A

A: It creates a nerve impulse (action potential) that travels through its axon to the CNS.

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69
Q

Q: What is the structure of a sensory neuron?

A

A: Usually pseudounipolar, with sensory receptor (dendrites), axon, and cell body located along the axon.

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70
Q

Q: Where are sensory neurons located?

A

A: In the Peripheral Nervous System (PNS).

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71
Q

Q: Where are interneurons located?

A

A: In the Central Nervous System (CNS).

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72
Q

Q: What is the function of sensory receptor dendrites?

A

A: To detect stimuli.

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73
Q

Q: What is the primary function of interneurons?

A

A: To integrate sensory input and formulate responses.

74
Q

Q: What are effectors?

A

A: Muscles or glands that react to signals from motor neurons.

75
Q

Q: What is the correct flow of information in the nervous system?

A

A:
Sensory neuron → Interneuron → Motor neuron → Effectors.

76
Q

Q: Where are motor neurons’ signals directed?

A

A: To effectors (muscles or glands).

77
Q

Q: What is the role of neurotransmitters in sensory neurons?

A

A: To transmit signals from sensory neurons to interneurons in the CNS at synapses.

78
Q

Q: How do interneurons use neurotransmitters?

A

A: To relay signals to other neurons, including motor neurons, after processing sensory information.

79
Q

Q: What is the role of neurotransmitters in motor neurons?

A

A: To stimulate muscle contraction or gland secretion at neuromuscular junctions.

80
Q

Q: What is a neuromuscular junction?

A

A: The synapse where motor neurons release neurotransmitters to stimulate muscles or glands.

81
Q

Q: What is the overall importance of neurotransmitters in the nervous system?

A

transmission of sensory information, processed signals, and motor commands through synapses.

82
Q

Q: What is the primary function of sensory neurons?

A

A: To detect stimuli and generate nerve impulses.

83
Q

Q: What is the primary function of interneurons?

A

A: To process incoming sensory information and decide on appropriate responses.

84
Q

Q: What is the primary function of motor neurons?

A

A: To send motor impulses to effectors (muscles or glands).

85
Q

Q: Where do neurotransmitters function in the nervous system?

A

A: At synapses between neurons and at neuromuscular junctions.

86
Q

Q: What is a motor unit?

A

A: One motor neuron and all the muscle fibers it connects to.

87
Q

Q: What happens when a motor neuron sends a signal?

A

A: It activates all muscle fibers in its motor unit simultaneously, leading to muscle contraction.

88
Q

Q: What is neuroglia?

A

A: Support cells in the nervous system that make up about half of the CNS’s volume.

89
Q

Q: What are two key differences between neuroglia and neurons?

A

A: Neuroglia can multiply and divide, and they don’t conduct nerve impulses.

90
Q

Q: How many types of neuroglia are there and where are they found?

A

A: Six types total: four in CNS (astrocytes, oligodendrocytes, microglia, ependymal cells) and two in PNS (Schwann cells, satellite cells).

91
Q

Q: What happens when neurons die?

A

A: Neuroglia fills in the spaces left by the dead neurons.

92
Q

Q: What is a glioma?

A

A: A usually malignant brain tumor formed from glial cells.

93
Q

Q: What are two key characteristics of neuroglia?

A

A: They are not electrically excitable and do not transmit action potentials.

94
Q

Q: How do neuroglia compare in size to neurons?

A

A: They are smaller than neurons but more numerous.

95
Q

Q: What are the functions of astrocytes?

A

A: Provide structural support, maintain the blood-brain barrier, guide neuron growth, regulate chemical balance, and influence synapse formation.

96
Q

Q: What is the role of oligodendrocytes in the CNS?

A

A: To form and maintain the myelin sheath around CNS axons, insulating them and speeding up nerve impulse transmission.

97
Q

Q: What is the myelin sheath and its function?

A

A: A multi-layered lipid and protein covering that insulates axons and increases the speed of action potentials.

97
Q

Q: What are ependymal cells responsible for?

A

A: Producing and monitoring cerebrospinal fluid (CSF), which protects and nourishes the spinal cord and brain.

98
Q

Q: What is the function of microglia?

A

A: They act as phagocytes, clearing away cellular debris and microbes in the CNS.

99
Q

Q: What is the role of Schwann cells in the PNS?

A

A: To encircle PNS axons and form myelin sheaths, aiding in axon regeneration.

100
Q

Q: What do satellite cells do in the PNS?

A

A: Provide structural support and regulate nutrient exchange between neurons and interstitial fluid.

101
Q

Q: What are the two types of astrocytes, and where are they found?

A

A: Protoplasmic astrocytes (in gray matter) and fibrous astrocytes (mainly in white matter).

102
Q

Q: How do ependymal cells contribute to brain protection?

A

A: They form a barrier between blood and cerebrospinal fluid (CSF) and circulate CSF in the ventricles of the brain.

103
Q

Q: What is the appearance of microglial cells?

A

A: Small cells with slender, spinelike projections that resemble macrophages in function and structure.

104
Q

Q: What does myelinated mean?

A

A: Axons that are covered by a myelin sheath, which insulates and speeds up nerve signals.

105
Q

Q: What cells produce myelin in the PNS vs. CNS?

A

A: Schwann cells in the PNS; oligodendrocytes in the CNS.

106
Q

Q: How do Schwann cells differ from oligodendrocytes in myelination?

A

A: Schwann cells wrap around one axon segment, while oligodendrocytes cover parts of several axons.

107
Q

Q: What are nodes of Ranvier?

A

A: Gaps between myelin segments that help speed impulse conduction.

108
Q

Q: Why is regeneration more effective in the PNS?

A

A: Due to the presence of the neurolemma (peripheral nucleated cytoplasmic layer of Schwann cells).

109
Q

Q: What is the neurolemma?

A

A: The peripheral, nucleated cytoplasmic layer of the Schwann cell.

110
Q

Q: How does myelination change from birth?

A

A: It increases over time, improving nerve signal speed and coordination.

111
Q

Q: How do Schwann cells aid in axon repair?

A

A: By forming a regeneration tube.

112
Q

Q: Why is repair limited in the CNS?

A

A: Because oligodendrocytes lack a neurolemma.

113
Q

most axons in CNS & PNS are ____.

A

Myelinated

114
Q

Most axons found in the autonomic nervous system are ___.

A

unmeylinated

115
Q

What types of cells form the myelin sheath?

A

Schwann cells and oligodendrocytes

116
Q

where are schwann cells found?

A

PNS

117
Q

what does each schwann cell myelinate?

A

a single axon segment.

118
Q

where are oligodendrocytes found?

A

found in the central nervous system (CNS).

119
Q

what can each oligodendrocyte myelinate?

A

parts of multiple axons.

120
Q

Q: What are the three stages of myelin sheath formation?

A

A:
1. Initial stage (Schwann cell begins wrapping)
2. Progressing stage (multiple membrane layers form spiral)
3. Final stage (complete sheath with neurolemma and nodes of Ranvier)

121
Q

Q: What defines whether an axon is myelinated or unmyelinated?

A

A: Myelinated axons have a myelin sheath covering; unmyelinated axons do not.

122
Q

Q: How do Schwann cells and oligodendrocytes differ in myelination?

A

A: Schwann cells wrap around one axon segment with a neurolemma, while oligodendrocytes cover multiple axons without a neurolemma.

123
Q

Q: What is the significance of the neurolemma?

A

A: It helps repair the axon and is present only in PNS (Schwann cells).

124
Q

Q: Why do infants have slower responses than adults?

A

A: Due to incomplete myelination, which develops progressively from birth to adulthood.

125
Q

Q: What happens during the progressing stage of myelination?

A

A: The Schwann cell wraps multiple layers of its membrane around the axon in a spiral pattern.

126
Q

Q: What is formed in the final stage of myelination?

A

A: A complete myelin sheath with the neurolemma as the outer layer and nodes of Ranvier between successive Schwann cells.

127
Q

Q: What is the primary function of myelin?

A

A: To increase the speed of nerve impulse transmission.

128
Q

Q: What are nodes of Ranvier and why are they important?

A

A: Gaps along the myelinated axon that aid in speeding up nerve impulses.

129
Q

what is the myeline sheath?

A

is a lipid and protein covering around axons that increases nerve impulse speed. Axons with this sheath are “myelinated”; those without are “unmyelinated.“

130
Q

Q: What is Multiple Sclerosis (MS)?

A

A: An autoimmune disease that progressively destroys myelin sheaths around neurons in the CNS.

131
Q

Q: How many people are affected by MS?

A

A: About 350,000 people in the U.S. and 2 million worldwide.

132
Q

Q: What causes MS?

A

A: Exact cause is unclear but may involve both genetic and environmental factors, possibly including herpes virus as a trigger.

133
Q

Q: What are the main symptoms of MS?

A

A: Muscle weakness, abnormal sensations, and double vision.

134
Q

Q: What is the most common form of MS?

A

A: Relapsing-remitting MS.

135
Q

Q: What happens in relapsing-remitting MS?

A

A: Attacks of symptoms followed by periods of remission, typically occurring every year or two.

136
Q

Q: What are scleroses in MS?

A

A: Hardened scars that form and disrupt nerve signal transmission.

137
Q

Q: How does MS affect the nervous system?

A

A: The immune system attacks myelin sheaths, disrupting normal nerve signal transmission.

138
Q

Q: What is the nature of MS as a disease?

A

A: It’s an autoimmune disease where the body’s immune system attacks its own myelin.

139
Q

Q: What are nodes of Ranvier?

A

A: Gaps between myelin sheaths where the axon is exposed, containing ion channels for sodium and potassium.

140
Q

Q: What type of ion channels are found in nodes of Ranvier?

A

A: Voltage-gated sodium (Na+) channels.

141
Q

Q: What is saltatory conduction?

A

A: The process where nerve impulses “jump” from one node of Ranvier to the next along a myelinated axon.

142
Q

Q: How do nodes of Ranvier increase signal transmission speed?

A

A: By allowing action potentials to jump between nodes rather than traveling along the entire axon length.

143
Q

Q: What is the main function of myelin sheaths between nodes?

A

A: To insulate the axon and speed up transmission of nerve impulses.

144
Q

Q: What ions are exchanged at the nodes of Ranvier?

A

A: Sodium (Na+) and potassium (K+) ions.

145
Q

Q: Why is saltatory conduction more efficient than continuous conduction?

A

A: Because the signal jumps between nodes rather than traveling the entire length of the axon, making transmission faster.

146
Q

Q: What makes saltatory conduction possible?

A

A: The combination of myelinated sections and exposed nodes of Ranvier with ion channels.

147
Q

Q: What are the three major factors affecting nerve impulse speed?

A

A: 1. Amount of myelination 2. Axon diameter 3. Temperature

148
Q

Q: How does axon diameter affect nerve impulse speed?

A

A: Larger diameter axons propagate action potentials faster due to larger surface areas.

149
Q

Q: How does myelination affect nerve impulse speed?

A

A: More myelin increases the speed of action potentials.

150
Q

Q: How does temperature affect nerve impulse speed?

A

A: Higher temperatures increase the speed of action potentials; lower temperatures decrease speed.

151
Q

Q: Why might temperature effects on nerve impulse speed be relevant to warm-up?

A

A: Because warming up increases temperature, which could increase nerve impulse speed.

152
Q

Q: Which type of axon conducts nerve impulses faster?

A

A: Myelinated axons conduct faster than unmyelinated axons.

153
Q

Q: What happens to nerve impulse speed when an axon is cooled?

A

A: The speed decreases.

154
Q

Q: Why do larger diameter axons conduct faster?

A

A: Because they have larger surface areas for impulse propagation.

155
Q

Q: What are the two types of electrical signals used by neurons for communication?

A

A: Graded potentials and action potentials (nerve impulses).

156
Q

Q: What is the function of graded potentials?

A

A: To transmit short-distance signals within a neuron.

157
Q

Q: What is the function of action potentials?

A

A: To transmit long-distance signals along the axon.

158
Q

Q: How do graded potentials differ from action potentials?

A

A: Graded potentials vary in magnitude and can decay over distance, while action potentials are all-or-nothing and propagate without decay.

159
Q

Q: Where do graded potentials typically occur?

A

A: At the dendrites or cell body of a neuron.

160
Q

Q: Where do action potentials occur?

A

A: Along the axon of a neuron, especially at the axon hillock after summation of graded potentials.

161
Q

Q: How are graded potentials initiated?

A

A: By stimuli such as neurotransmitters binding to receptors or sensory input.

162
Q

Q: What is the minimum threshold that must be reached for an action potential to occur?

A

A: A critical level of depolarization, known as the threshold potential.

163
Q

Q: What are the two main features of excitable cell membranes that underlie graded potentials and action potentials?

A

A: Resting membrane potential and specific ion channels.

164
Q

Q: What is the resting membrane potential?

A

A: The electrical difference (voltage) across the membrane when a neuron is not actively transmitting signals, similar to voltage in a battery.

165
Q

Q: How does current flow in excitable cells?

A

A: Current flows through the movement of ions, not electrons, across the cell membrane.

166
Q

Q: What allows graded potentials and action potentials to occur in neurons?

A

A: The presence of various ion channels that open or close in response to specific stimuli.

167
Q

Q: Why is the lipid bilayer of the plasma membrane a good insulator?

A

A: It prevents the free flow of ions, making ion channels the primary pathways for ion movement across the membrane.

168
Q

Q: What is the role of ion channels in neuron signaling?

A

A: Ion channels facilitate the movement of ions across the membrane, which is essential for generating and propagating electrical signals in neurons.

169
Q

Q: How does the flow of ions relate to the concept of a battery?

A

A: Just as a battery allows current to flow when connected, the resting membrane potential creates an environment for ions to flow, generating electrical currents in excitable cells.

170
Q

Q: What happens to ion channels in response to specific stimuli?

A

A: They open or close, allowing ions to enter or exit the neuron, which can alter the membrane potential and initiate graded potentials or action potentials.

171
Q

Q: What are the key characteristics of an action potential?

A

A:
- All-or-nothing response
- Same strength every time
- Travels in one direction
- Allows long-distance communication

172
Q

Q: What is the sequence of ion channel changes during an action potential?

A

A:
1. Sodium channels open (ions rush in)
2. Depolarization occurs
3. Potassium channels open (ions flow out)
4. Repolarization returns cell to resting state

173
Q

Q: What happens at neuromuscular junctions?

A

A: Action potential triggers neurotransmitter release, which crosses synapse to muscle fiber and causes contraction.

174
Q

Q: How does depolarization occur?

A

A: Sodium channels open, allowing positive ions to rush in, making the membrane more positive.

175
Q

Q: What is repolarization?

A

A: The process of returning to resting state when potassium channels open and positive ions flow out.

176
Q

Q: How does an action potential move along an axon?

A

A: It travels like a wave through sequential ion channel changes.

177
Q

Q: Why is the action potential’s “all-or-nothing” nature important?

A

A: It ensures consistent signal strength and reliable communication throughout the nervous system.

178
Q

Q: What makes neural communication effective?

A

A: It allows for rapid communication throughout body, precise muscle control, and coordinated responses to stimuli.

179
Q

Q: How do motor axons control muscles?

A

A: One motor axon can connect to multiple muscle fibers through neuromuscular junctions, allowing coordinated muscle control.

Kin 267 (Phys. 1) (14 decks)

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