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Questions and Answers
What is the primary function of the myelin sheath in the nervous system?
Which statement accurately describes gray matter?
What role do interneurons play in the nervous system?
The reflex arc is characterized by which of the following components?
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Depolarization in a neuron primarily leads to what physiological event?
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What is the primary role of the sympathetic nervous system?
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Which function is primarily associated with cerebrospinal fluid (CSF)?
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What is the main function of astrocytes in the nervous system?
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In what way does myelin affect nerve impulse conduction?
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Which part of the brain is responsible for coordinating muscle movements and balance?
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What are cranial nerves primarily responsible for?
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What best describes a dermatome?
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Multiple sclerosis primarily affects which structure in the nervous system?
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What is the primary role of astrocytes in the central nervous system?
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During the process of depolarization, which ion primarily enters the neuron?
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Which of the following accurately describes the function of the cerebellum?
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What differentiates white matter from gray matter in the CNS?
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What is the sequence of events in a simple reflex arc, such as the patellar reflex?
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Which component is NOT part of a synapse?
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In the context of the autonomic nervous system, which statement is true regarding the sympathetic and parasympathetic divisions?
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Study Notes
Neuron Structure
- A neuron is a specialized nerve cell with three main parts:
- Cell body: Contains the nucleus and other organelles
- Dendrites: Branching extensions that receive signals from other neurons
- Axon: A single, long extension that transmits signals away from the cell body
Neuron Types
- Sensory neurons (afferent neurons): Carry signals from sensory receptors to the CNS
- Motor neurons (efferent neurons): Carry signals from the CNS to muscles and glands
- Interneurons: Connect sensory and motor neurons within the CNS, allowing for complex processing of information
Glial Cells
- Astrocytes: Provide structural support, maintain the blood-brain barrier, and regulate nutrient and ion concentrations
- Microglia: Act as immune cells, engulfing debris and pathogens
- Oligodendrocytes: Form myelin sheaths around axons in the CNS, improving signal transmission speed
White Matter vs. Gray Matter
- White matter: Composed of myelinated axons, responsible for fast signal transmission over long distances
- Gray matter: Consists mainly of neuron cell bodies, dendrites, synapses, and unmyelinated axons, involved in processing information
Simple Reflex Arc
- A stimulus triggers sensory receptors, sending an impulse along a sensory neuron to the spinal cord.
- The impulse synapses with an interneuron within the spinal cord.
- Interneuron relays the signal to a motor neuron, triggering a response in an effector (muscle or gland).
Nerve Impulse Mechanism (Action Potential)
- Resting state: Neuron membrane is polarized, with more positive charges outside and more negative charges inside.
- Depolarization: A stimulus causes sodium ion channels to open, allowing sodium ions to rush into the neuron, making the inside more positive.
- Repolarization: Potassium ion channels open, allowing potassium ions to flow out, restoring the negative charge inside the neuron.
Synapse
- A junction between two neurons where nerve impulses are transmitted.
- Components:
- Presynaptic neuron: Contains synaptic vesicles filled with neurotransmitters
- Synaptic cleft: The space between the neurons
- Postsynaptic neuron: Contains receptors that bind to neurotransmitters
Cerebellum Function
- Coordinates muscle movements, contributing to smooth and precise motor control
- Maintains balance and posture
- Plays a role in learning and memory of motor skills
Autonomic Nervous System Divisions
- Sympathetic nervous system: Prepares the body for "fight-or-flight" responses, increasing heart rate, blood pressure, and respiration
- Parasympathetic nervous system: Promotes "rest-and-digest" functions, slowing heart rate, lowering blood pressure, and stimulating digestion
Cerebrospinal Fluid (CSF) Functions
- Cushions the brain and spinal cord, protecting them from injury
- Provides nutrients to the CNS
- Removes waste products
- Maintains a stable chemical environment for the CNS
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Description
This quiz covers the fundamental aspects of neuron structure, types, and the role of glial cells. It also differentiates between white matter and gray matter in the nervous system. Test your knowledge on how these components work together to transmit signals and support brain function.