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Neural Tissue Flashcards

1
Q
A
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2
Q

What are the two principal parts of the nervous system?

A
  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)

These two parts work together to process and respond to information.

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3
Q

What structures make up the central nervous system (CNS)?

A

Brain and spinal cord in the dorsal body cavity

The CNS serves as the command center for processing information.

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4
Q

What are the functions of the central nervous system (CNS)?

A

Integration and command center

The CNS coordinates all activities of the nervous system.

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5
Q

What structures are included in the peripheral nervous system (PNS)?

A

Nerves that extend to/from the brain (cranial nerves) and spinal cord (spinal nerves)

The PNS connects the CNS to the rest of the body.

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6
Q

What is the function of the peripheral nervous system (PNS)?

A

Link the command center (CNS) with the rest of the body

The PNS plays a critical role in communication between the CNS and peripheral organs.

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7
Q

What are the two functional divisions of the peripheral nervous system (PNS)?

A
  • Sensory division
  • Motor division

These divisions allow the PNS to gather information and respond to it.

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8
Q

What do somatic afferent fibers transmit impulses from?

A

Skin, skeletal muscle, and joint

These fibers are responsible for sensations from external body structures.

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9
Q

What do visceral afferent fibers transmit impulses from?

A

Visceral organs (ventral body cavity)

These fibers relay information about internal body conditions to the CNS.

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10
Q

What are the two parts of the motor (efferent) division?

A
  • Somatic (voluntary) nervous system
  • Autonomic (involuntary) nervous system (ANS)

These parts control voluntary and involuntary actions, respectively.

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11
Q

What does the somatic (voluntary) nervous system do?

A

Conducts impulses from CNS to skeletal muscles

This system is responsible for voluntary muscle movements.

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12
Q

Functions of the nervous system—

A

Sensory input, integration, motor output

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13
Q

What does the autonomic nervous system (ANS) conduct impulses to?

A

Smooth muscle, cardiac muscle, and glands

The ANS is responsible for regulating involuntary bodily functions.

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14
Q

What are the two divisions of the autonomic nervous system?

A

Sympathetic nervous system and parasympathetic nervous system

These divisions counteract each other to maintain homeostasis.

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15
Q

What are the two kinds of cells in the nervous system?

A

Neurons and neuroglia (glial cells)

Neurons are the functional units, while neuroglia support and protect neurons.

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16
Q

What do neurons lack that most other cells have?

A

Centrioles

This contributes to their inability to divide.

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17
Q

What is the cytoplasm surrounding the nucleus of a neuron called?

A

Perikaryon

The perikaryon contains the cell’s organelles.

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18
Q

What structures are abundant in the cell body of a neuron?

A

Mitochondria, rough endoplasmic reticulum (RER), and free ribosomes

These structures are involved in energy production and neurotransmitter synthesis.

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19
Q

What are clusters of cell bodies in the CNS called?

A

Nuclei

In the PNS, these clusters are referred to as ganglia.

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20
Q

What is the function of dendrites in neurons?

A

Receptive or input region of the cell

Dendrites convey electrical signals known as graded potentials.

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21
Q

What percentage of a neuron’s surface area do dendrites comprise?

A

80 - 90%

Dendrites play a crucial role in receiving signals from other neurons.

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22
Q

How many axons does each neuron typically have?

A

One

The axon is responsible for carrying electrical signals away from the cell body.

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23
Q

What is the axon hillock?

A

Thick section of the cell body that attaches to the initial segment

It is critical for initiating action potentials.

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24
Q

Fill in the blank: The axon carries electrical signals known as _______.

A

Action potential

The action potential is the primary means of communication in the nervous system.

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25
What attaches to the axon hillock?
Initial segment ## Footnote The initial segment is the part of the neuron where action potentials are generated.
26
What are branches of a single axon called?
Collaterals ## Footnote Collaterals allow the axon to communicate with multiple target cells.
27
What are fine extensions of the distal axon referred to as?
Telodendria ## Footnote Telodendria facilitate the transmission of signals to other neurons or muscle cells.
28
What are the tips of the axon known as?
Synaptic terminals ## Footnote Synaptic terminals are where neurotransmitters are released to communicate with other cells.
29
What are the two structural classifications of neurons?
Sensory (afferent) neurons and Motor (efferent) neurons ## Footnote Neurons can also be classified based on their function and structure.
30
What do sensory (afferent) neurons transmit?
Impulses from body to CNS ## Footnote They play a crucial role in conveying sensory information to the central nervous system.
31
Where are the cell bodies of most sensory neurons located?
Outside the CNS in sensory ganglia ## Footnote This positioning allows for efficient transmission of sensory information.
32
What type of sensory neurons monitor internal sensations?
Interoceptors ## Footnote Interoceptors are involved in sensing changes within the body, such as hunger or thirst.
33
What do exteroceptors respond to?
External senses ## Footnote Exteroceptors detect stimuli from the external environment, like touch and temperature.
34
What type of sensory neurons monitor position and movement?
Proprioceptors ## Footnote Proprioceptors provide feedback about the position of body parts during movement.
35
What do motor (efferent) neurons transmit?
Impulses from CNS to body ## Footnote Motor neurons are responsible for sending signals that initiate muscle contraction.
36
What is the typical structure of motor neurons?
Multipolar ## Footnote Most motor neurons have multiple dendrites for integrating signals from other neurons.
37
Where are the cell bodies of most motor neurons located?
Usually in CNS ## Footnote This central location allows for direct control of muscle actions.
38
What are interneurons also known as?
Association neurons ## Footnote Interneurons connect sensory and motor neurons and play a key role in reflexes and higher brain functions.
39
Where are most interneurons located?
In brain, spinal cord, and autonomic ganglia ## Footnote Interneurons are crucial for processing information within the central nervous system.
40
What are the primary responsibilities of interneurons?
Distribution of sensory information and coordination of motor activity ## Footnote They integrate and relay information between sensory and motor pathways.
41
What higher functions are interneurons involved in?
Memory, planning, learning ## Footnote Interneurons contribute to complex cognitive processes in the brain.
42
What are neuroglia?
Supporting cells of the nervous system ## Footnote Neuroglia make up half the volume of the nervous system.
43
* Ependymal cells * Astrocytes * Oligodendrocytes * Microglia are all...
neuroglia ## Footnote Each type has distinct functions and characteristics.
44
What is the function of ependymal cells?
Secretes, circulates, monitors cerebrospinal fluid ## Footnote Ependymal cells form an epithelial layer called ependyma, often ciliated with microvilli.
45
What is the most abundant type of neuroglia?
Astrocytes ## Footnote Astrocytes support and brace neurons with a 3-dimensional framework.
46
What do astrocytes regulate in the interstitial environment?
*ions * Glucose/Lactic acid * Neurotransmitters ## Footnote Astrocytes help determine capillary permeability, contributing to the blood-brain barrier.
47
What do oligodendrocytes do?
Wrap around nerve fibers to form myelin sheath ## Footnote Oligodendrocytes provide insulation to nerve fibers.
48
What is the role of microglia in the CNS?
Monitor neuron health and respond to injury ## Footnote Microglia act as the immune system of the CNS, phagocytizing debris and microorganisms.
49
What are satellite cells also known as?
Amphicytes ## Footnote Satellite cells surround ganglia and may regulate the environment around neurons.
50
What do Schwann cells form around peripheral axons?
Myelin sheath ## Footnote Schwann cells are also referred to as neurilemmacytes.
51
How many Schwann cells sheath a segment of an axon?
One Schwann cell ## Footnote Many Schwann cells are needed to sheath the entire axon, forming nodes and internodes.
52
Myelination does what?
Insulates and increases speed
53
Internodes are--
myelinated segments of axon
54
Nodes/Nodes of Ranvier---
are the gaps between myelinated segements
55
Can neurons be replaced?
NO
56
PNS neuron damage, can it be fixed?
Sometimes
57
CNS neuron damage, can it be fixed?
NOPE
58
Hyperpolarization occurs when---
inside of the membrane becomes more negative than when resting –– Reduces the probability of producing a nerve impulse
59
Study the difference between action potential and graded potential --
elsewhere
60
MS is ---
when myelinated segments become nonfunctional and short circuit things
61
What is the role of autonomic ganglia?
Autonomic ganglia transmit signals from CNS motor neurons to visceral effectors.
62
Where do signals from CNS motor neurons to visceral effectors synapse?
Signals synapse in autonomic ganglia.
63
What is synaptic potentiation?
Synaptic potentiation refers to the increase in efficiency of neurotransmission due to repeated use of synapses.
64
How does synaptic potentiation occur?
Synaptic potentiation occurs when Ca²⁺ concentration increases in both the presynaptic terminal and the postsynaptic neuron, enhancing neurotransmission.
65
What effect does high-frequency stimulation have on the postsynaptic neuron?
High-frequency stimulation partially depolarizes the postsynaptic neuron, allowing Ca²⁺ entry through NMDA receptors, which activates kinase enzymes to promote more effective responses to subsequent stimuli.
66
What is presynaptic inhibition?
Presynaptic inhibition occurs when the release of an excitatory neurotransmitter by one neuron is inhibited by the activity of another neuron through axoaxonic synapses.
67
What is the result of presynaptic inhibition?
Less neurotransmitter is released, leading to smaller EPSPs (excitatory postsynaptic potentials).
68
How can presynaptic inhibition and facilitation affect action potential production?
Presynaptic inhibition and facilitation can affect the production of action potentials in the presynaptic neuron by altering neurotransmitter release.
69
How is the strength of a signal in the nervous system measured?
The strength of a signal is measured by the frequency of action potentials in the postsynaptic neuron.
70
Why can't the magnitude of action potentials be used to measure signal strength?
The magnitude of action potentials cannot be used because all action potentials have the same magnitude (approximately -70 to +30 mV).
71
How many neurotransmitters can most neurons release?
Most neurons release two or more neurotransmitters, depending on the stimulation frequency.
72
How many neurotransmitters have been identified?
Over 50 neurotransmitters have been identified.
73
How are neurotransmitters classified?
Neurotransmitters are classified by chemical structure and function.
74
What is acetylcholine (ACh)?
Acetylcholine is a neurotransmitter released at neuromuscular junctions and some ANS neurons. It is synthesized by choline acetyltransferase and degraded by acetylcholinesterase (AChE).
75
What are catecholamines?
Catecholamines include dopamine, norepinephrine (NE), and epinephrine. They are involved in emotional behaviors and the biological clock.
76
What are indolamines?
Indolamines include serotonin and histamine, which are involved in mood regulation and other functions.
77
What amino acids act as neurotransmitters?
Important amino acid neurotransmitters include GABA, glycine, aspartate, and glutamate.
78
What are neuropeptides (peptides) and name some examples?
Neuropeptides are neurotransmitters that include substances like substance P (mediates pain signals) and endorphins (natural pain reducers).
79
What are gut-brain peptides and name examples?
Gut-brain peptides include somatostatin and cholecystokinin, which play roles in digestion and brain function.
80
What are purines and how do they act in the CNS and PNS?
Purines, like ATP, act in both the CNS and PNS, inducing fast or slow responses, provoking pain sensations, and promoting Ca²⁺ influx in astrocytes.
81
What is the role of nitric oxide (NO) as a neurotransmitter?
Nitric oxide is synthesized on demand and activates the intracellular receptor guanylyl cyclase to produce cyclic GMP, which is involved in learning and memory.
82
What is carbon monoxide (CO) and its role in the brain?
Carbon monoxide regulates cGMP in the brain and plays a role in signaling and brain function.
83
What are endocannabinoids?
Endocannabinoids are lipid-soluble neurotransmitters synthesized on demand from membrane lipids. They bind with G-protein coupled receptors and are involved in learning and memory.
84
What determines whether a neurotransmitter is excitatory or inhibitory?
A neurotransmitter's effect (excitatory or inhibitory) depends on the type of receptor on the postsynaptic neuron.
85
Which neurotransmitters are usually inhibitory?
GABA and glycine are usually inhibitory neurotransmitters.
86
Which neurotransmitter is usually excitatory?
Glutamate is usually an excitatory neurotransmitter.
87
How does acetylcholine (ACh) function in different muscles?
Acetylcholine is excitatory at neuromuscular junctions in skeletal muscle and inhibitory in cardiac muscle.
88
What is direct action of neurotransmitters?
Direct action occurs when a neurotransmitter binds to a channel-linked receptor and opens ion channels, promoting rapid responses.
89
What is indirect action of neurotransmitters?
Indirect action involves a neurotransmitter binding to a G-protein-linked receptor, acting through second messengers for long-lasting effects.
90
What is an example of a neurotransmitter that acts directly?
Acetylcholine (ACh) and amino acids are examples of neurotransmitters that act directly.
91
What is an example of neurotransmitters that act indirectly?
Biogenic amines, neuropeptides, and dissolved gases act indirectly.
92
What are channel-linked (ionotropic) receptors?
These are ligand-gated ion channels that cause immediate and brief responses. Excitatory receptors allow Na+ influx, while inhibitory receptors allow Cl- influx or K+ efflux.
93
What are G-protein-linked (metabotropic) receptors?
G-protein-linked receptors are transmembrane protein complexes that cause indirect, slow, and often prolonged responses.
94
How do G-protein-linked receptors function?
When neurotransmitters bind to these receptors, they activate G-proteins, which control second messengers like cyclic AMP or Ca²⁺.
95
What is the mechanism of action for second messengers in G-protein-linked receptors?
Second messengers can open/close ion channels, activate kinases, phosphorylate proteins, or activate genes for protein synthesis.
96
What are neuronal pools?
Neuronal pools are functional groups of neurons that integrate incoming information and forward processed information to other destinations.
97
What is a simple neuronal pool?
A simple neuronal pool consists of a single presynaptic fiber that branches and synapses with several neurons, creating discharge and facilitated zones.
98
What is a diverging circuit in a neuronal pool?
In a diverging circuit, one incoming fiber stimulates an increasing number of fibers, amplifying the signal. It is common in sensory and motor systems.
99
What is a converging circuit in a neuronal pool?
A converging circuit results in strong stimulation or inhibition, and is common in sensory and motor systems.
100
What is a reverberating (oscillating) circuit?
A reverberating circuit involves a chain of neurons with collateral synapses that cycle back to previous neurons in the chain.
101
What is a parallel after-discharge circuit?
In a parallel after-discharge circuit, one incoming fiber stimulates several neurons in parallel, which all stimulate a common output cell.
102
What is serial processing in neural processing?
Serial processing is when input travels along one pathway to a specific destination, producing an all-or-none response, such as in reflexes.
103
What is parallel processing in neural processing?
Parallel processing involves input traveling along several pathways, leading to multiple responses. It is important for higher-level mental functions, like remembering past experiences linked to smells.

Nervous System (7 decks)

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