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Questions and Answers
Which statements correctly describe the function of myelination in the peripheral nervous system?
Which statements correctly describe the function of myelination in the peripheral nervous system?
What role do perineuronal satellite cells play in the nervous system?
What role do perineuronal satellite cells play in the nervous system?
How are unmyelinated axons in the PNS structurally different from myelinated axons?
How are unmyelinated axons in the PNS structurally different from myelinated axons?
Which of the following best describes the function of microglia?
Which of the following best describes the function of microglia?
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What initiates the process of myelination by Schwann cells?
What initiates the process of myelination by Schwann cells?
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What characteristic distinguishes pseudounipolar neurons from unipolar neurons?
What characteristic distinguishes pseudounipolar neurons from unipolar neurons?
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Where are the neural cell bodies of sensory neurons typically located?
Where are the neural cell bodies of sensory neurons typically located?
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Which type of neuron has a very long axon and collects stimuli via a long dendrite?
Which type of neuron has a very long axon and collects stimuli via a long dendrite?
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What is a key feature of multipolar neurons?
What is a key feature of multipolar neurons?
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What role does the axon hillock play in neuron function?
What role does the axon hillock play in neuron function?
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Which part of a neuron is primarily responsible for propagating electrical impulses away from the soma?
Which part of a neuron is primarily responsible for propagating electrical impulses away from the soma?
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What distinguishes bipolar neurons in terms of their structural morphology?
What distinguishes bipolar neurons in terms of their structural morphology?
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What type of axon structure may not contain elements such as Golgi apparatus or free ribosomes?
What type of axon structure may not contain elements such as Golgi apparatus or free ribosomes?
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What type of neuron primarily sends signals away from the cell body to effectors?
What type of neuron primarily sends signals away from the cell body to effectors?
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Which neuron type primarily participates in sensory functions by detecting stimuli?
Which neuron type primarily participates in sensory functions by detecting stimuli?
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What is the primary function of interneurons?
What is the primary function of interneurons?
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In the motor neuron system, which type of neuron is responsible for the initial signal transmission to target muscles?
In the motor neuron system, which type of neuron is responsible for the initial signal transmission to target muscles?
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Which type of neuron is primarily responsible for transmitting signals from sensory receptors to the central nervous system?
Which type of neuron is primarily responsible for transmitting signals from sensory receptors to the central nervous system?
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What is the primary role of interneurons within the nervous system?
What is the primary role of interneurons within the nervous system?
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What is the characteristic feature of multipolar neurons?
What is the characteristic feature of multipolar neurons?
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What type of synapse primarily relies on neurotransmitter diffusion between neurons?
What type of synapse primarily relies on neurotransmitter diffusion between neurons?
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Which glial cell type is primarily responsible for maintaining the blood-brain barrier?
Which glial cell type is primarily responsible for maintaining the blood-brain barrier?
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Which components of neurons are directly involved in synaptic integration?
Which components of neurons are directly involved in synaptic integration?
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What aspect of axonal transport primarily moves substances from the axon terminal back to the cell body?
What aspect of axonal transport primarily moves substances from the axon terminal back to the cell body?
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What is the main function of oligodendrocytes in the central nervous system?
What is the main function of oligodendrocytes in the central nervous system?
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Which type of synapse is characterized by direct transfer of electrical signals through gap junctions?
Which type of synapse is characterized by direct transfer of electrical signals through gap junctions?
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Which characteristic is most commonly associated with the excitability of neurons?
Which characteristic is most commonly associated with the excitability of neurons?
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What process declines in neurons as they mature and cannot divide?
What process declines in neurons as they mature and cannot divide?
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What type of glial cell is responsible for immune defense in the central nervous system?
What type of glial cell is responsible for immune defense in the central nervous system?
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What is the typical structure found at the presynaptic terminal of a chemical synapse?
What is the typical structure found at the presynaptic terminal of a chemical synapse?
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Which part of the neuron is primarily responsible for processing and integrating incoming signals?
Which part of the neuron is primarily responsible for processing and integrating incoming signals?
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What feature differentiates myelinated axons from unmyelinated ones?
What feature differentiates myelinated axons from unmyelinated ones?
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Which part of the nervous system contains both the spinal cord and the brain?
Which part of the nervous system contains both the spinal cord and the brain?
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Which type of astrocyte is predominantly found in white matter?
Which type of astrocyte is predominantly found in white matter?
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What is a primary function of astrocytes in the nervous system?
What is a primary function of astrocytes in the nervous system?
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Which of the following statements about glial cells is TRUE?
Which of the following statements about glial cells is TRUE?
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What type of cell is primarily responsible for the formation of the myelin sheath in the peripheral nervous system?
What type of cell is primarily responsible for the formation of the myelin sheath in the peripheral nervous system?
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Which type of astrocyte has thicker, highly branched processes and is mainly found in gray matter?
Which type of astrocyte has thicker, highly branched processes and is mainly found in gray matter?
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What role do astrocytes play during injury responses in the nervous system?
What role do astrocytes play during injury responses in the nervous system?
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How do astrocytes contribute to maintaining electrolyte balance in the extracellular environment?
How do astrocytes contribute to maintaining electrolyte balance in the extracellular environment?
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Which of these cells is considered the main immune defense in the central nervous system?
Which of these cells is considered the main immune defense in the central nervous system?
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What potential consequence is linked to the proliferation of glial cells?
What potential consequence is linked to the proliferation of glial cells?
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Which statement accurately describes the recovery function of astrocytes?
Which statement accurately describes the recovery function of astrocytes?
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Study Notes
Nervous System Architecture
- The nervous system receives, processes, integrates, and responds to information.
- It enables perception and cognition.
- It controls somatic and visceral system activities.
Central Nervous System (CNS)
- Comprised of the brain and spinal cord.
- Contains nerve fibers and ganglia outside of brain and spinal cord.
Peripheral Nervous System (PNS)
- Includes nerve fibers and ganglia outside of the brain and spinal cord.
- Contains special nerve endings.
Functional Divisions of the Nervous System
- Somatic Nervous System (SNS): Voluntary, conscious control of body activities. Provides motor and sensory innervation to all parts of the body (excluding internal organs, smooth muscles, and glands).
- Autonomic Nervous System (ANS): Controls cardiac muscles, smooth muscles, and glands. Provides sensory innervation to internal organs.
Nervous Tissue: Basic Components
- Neurons (Nerve cells): Process and integrate information.
- Glial cells (Neuroglial cells): Support and glue neural cells. They make up 90% of the nervous system.
Glial Cells
- Differentiated and developed from Neural Stem Cells (neuroepithelial cells), which are multipotent.
- In the CNS, neuroepithelial cells can develop into all types of neuroglial cells and neurons.
- Grey matter: Neuronal cell bodies, neuropil (unmyelinated axons and dendrites), glial cells, and capillaries. Involved in synaptic integration, information processing, motor control, and sensory perception.
Structures of Nerve Fibers
- Axon and myelin sheath
- Endoneurium
- Nerve fascicle
- Perineurium
- Nerve trunk
- Epineurium
Neuron Structure
- Cytoplasm: Contains nucleus, rough endoplasmic reticulum (rough ER; Nissl bodies), smooth endoplasmic reticulum (smooth ER), nucleus, and organelles.
- Dendrites: Propagate electrochemical stimulation to the soma. Branched extensions of cytoplasm from the soma. They receive signals from other neurons, forming a large dendritic field for wider detection of stimuli.
- Axon: Conducts electrical impulses away from the soma, usually long and slender. Myelinated or unmyelinated
Neuron Morphology and Classification
- Unipolar, Pseudounipolar, Bipolar, and Multipolar: Depending on the number of processes (extensions) arising from the cell body.
- Pseudounipolar: Looks like a unipolar neuron but actually has two processes. The peripheral axon carries signals to the soma from receptors, and the central axon carries impulses to the CNS. Found in sensory neurons.
- Bipolar: One dendrite and one axon. Found in special sense organs (e.g., olfactory and retina).
- Multipolar: Many dendrites and one axon. Most common type, including motor and interneurons.
Interneurons (Interneurons)
- Found in the brain's motor cortex.
- Collect signals from one neuron then sends signals to other.
- Involved in integration of information, process, store, retrieve, and make decisions.
- Small neurons form networks with unmyelinated axons.
Synapse Classification
- Chemical synapse: Chemical signals (ions) are transferred to chemical signals (then back to electrical signals). Neurotransmitters are released from the presynaptic neuron to carry signals across the synaptic cleft.
- Electrical synapse: Electrical signals (ions) move directly between synapses. Common in smooth muscle cells, cardiac muscle cells, and retinal cells.
Axonal Transport
- Newly synthesized protein molecules are transported to distant locations within neurons.
- Antrograde transport: Moves materials from the cell body to axon terminals.
- Retrograde transport: Moves materials from axon terminals to the cell body.
Postsynaptic Terminal & Membrane
- Contain membrane receptors and ion gates to receive chemical signals.
- A synaptic cleft separates the pre- and postsynaptic membranes (20-30nm of space).
Types of Neuroglia: Central Nervous System
- Astrocytes: Largest glial cells with many branches(both fibrous and protoplasmic). Provide structural support, maintain and repair BBB, and participate in the injury response.
- Oligodendrocytes: Form myelin sheaths around CNS axons, accelerating signal transmission.
- Microglia: Smallest neuroglia, immune surveillance cells.
- Ependymal cells: Epithelial-like cells lining ventricles of the brain and involved in CSF production.
Types of Neuroglia: Peripheral Nervous System
- Schwann cells: Form myelin sheaths around PNS axons. Allow for fast signal transmission and axon regeneration when injury occurs.
- Satellite cells: Surround neuron cell bodies in ganglia. Provide metabolic support and protection.
Nerve Injury and Regeneration
- CNS: Regeneration is slower or blocked by inhibitory factors and glial scar formation.
- PNS: Regeneration is possible, with Schwann cells promoting axon regrowth.
Saltatory Conduction
- Action potentials jump between myelinated regions (nodes of Ranvier) on axons, increasing conduction velocity.
Unmyelinated Axons
- Schwann cells tightly cover the axon.
- Nodes of Ranvier do not form.
- Axons fit into grooves of schwann cells.
Antigen-Presenting Cells
- Activated during injury, they become enlarged, amoeboid shaped
- Involved in phagocytosis and surveillance.
- Present antigens with other cells.
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Description
This quiz covers the architecture of the nervous system, including the central and peripheral nervous systems. It explores functional divisions like the somatic and autonomic nervous systems and the basic components such as neurons. Test your knowledge on how the nervous system operates and its various functions.
