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Questions and Answers
What characterizes direct control of movement?
Which statement is true about white matter?
What is a function of the medulla?
How are local potentials generated?
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Which functional nerve division is responsible for voluntary control of body movements?
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What structures are surrounded by the meninges?
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What distinguishes grey matter from white matter?
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What is the role of glial cells in the nervous system?
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What type of control involves brain cognition before triggering movement?
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Which structure is responsible for communication between different brain regions and the spinal cord?
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What is the primary function of glial cells in the nervous system?
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Which part of the brain is primarily associated with posture and balance?
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What type of potential is generated primarily at the dendrites or soma?
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Which type of nerve division carries sensory information from the body to the central nervous system?
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Which layer of the meninges is closest to the brain?
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What does the term 'decussation' refer to in the context of the nervous system?
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Which type of cells can differentiate into neurons under certain conditions?
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What role do voltage-gated channels play in the nervous system?
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Study Notes
Control of Movement
- Direct control: A direct connection between sensation and movement.
- Indirect control: Sensation first passes through the brain for processing and cognition before movement is initiated.
Central Nervous System (CNS) and Peripheral Nervous System (PNS) Structures
- White matter: Myelinated axons responsible for communication. In the PNS it's known as a tract, while in the CNS it's a nerve.
- Grey matter: Unmyelinated cell bodies, dendrites, and synapses responsible for processing information. In the PNS it's known as a nucleus, while in the CNS it's a ganglion.
Functional Nerve Divisions
- Somatic nervous system: Voluntary control of skeletal muscle, with connections from the spinal cord to the body.
- Autonomic nervous system: Involuntary control of smooth muscle and glands, with connections from the spinal cord and brainstem.
- Cranial nervous system: Controls sensory and motor functions, as well as special senses, with connections from the brainstem to the head and neck.
Peripheral Nervous System (PNS) Concepts
- Spinal nerves: 31 pairs of nerves originating from the spinal cord, forming plexuses and carrying mixed motor and sensory information.
- Cranial nerves: 12 pairs of nerves originating from the brainstem, with some carrying sensory information, others motor information, and some both.
Central Nervous System (CNS) Concepts
- Tract: A bundle of axons in the CNS responsible for transmitting information.
- Nucleus: A cluster of cell bodies in the CNS responsible for controlling specific functions.
- Decussation: The crossing of nerve fibers over the midline of the brain.
Brainstem
- Medulla: Responsible for vital functions like arousal and respiration.
- Pons: Plays a role in posture and balance control.
- Midbrain: Involved in orienting the body to stimuli.
Cerebellum
- Motor functions: Coordination, balance, and movement precision.
- Cognitive functions: Learning, memory, and language processing.
Cerebrum
- Two hemispheres: Left and right hemispheres responsible for different cognitive functions.
- Grey and white matter: Composed of both grey and white matter, forming a complex neural network.
Cortex
- Brain lobes: Frontal, parietal, temporal, and occipital lobes, each with specialized functions.
- Complex functions: Sensory perception, motor control, language, and higher cognitive processes.
Meninges
- Protective layers: Dura mater, pia mater, and arachnoid mater, surrounding the CNS.
Stem Cells
- Progenitor cells: Undifferentiated cells with the potential to develop into neurons.
Glial Cells
-
Macroglia: Support, nourish, and insulate neurons.
- Astrocytes: Provide structural support and regulate nutrient and waste exchange.
- Oligodendrocytes: Myelinate axons in the CNS.
- Schwann cells: Myelinate axons in the PNS.
- Microglia: Immune cells that remove cellular debris and pathogens.
Local Potential
- Location: Dendrites and soma (cell body).
-
Types:
- Excitatory: Depolarize the membrane, making it more likely to fire an action potential.
- Inhibitory: Hyperpolarize the membrane, making it less likely to fire an action potential.
- Mechanism: Opening and closing of ion channels allows the flow of ions like sodium (depolarization) or potassium/chloride (hyperpolarization).
Integration of Action Potential
- What: Triggered response that propagates along the axon.
- Location: Voltage-gated channels, primarily at the axon hillock.
- Mechanism: Changes in membrane potential cause the opening and closing of voltage-gated ion channels, generating an electrical signal that travels along the axon.
Movement Control
- Direct control: Sensory input directly triggers movement
- Indirect control: Sensory input processed by the brain before triggering movement
Nervous System Structure
- White matter: Myelinated axons, responsible for communication between brain regions and the spinal cord
- Grey matter: Unmyelinated cell bodies and dendrites, responsible for processing information, sensory perception, and decision-making
Functional Nerve Divisions
- Somatic nervous system: Controls voluntary movement of skeletal muscles
- Autonomic nervous system: Controls involuntary actions of smooth muscle and glands
- Cranial nervous system: Controls sensory and motor functions of the head and neck
Peripheral Nervous System (PNS)
- Spinal nerves: 31 pairs of nerves originating from the spinal cord, responsible for mixed motor and sensory functions
- Cranial nerves: 12 pairs of nerves originating from the brainstem, responsible for sensory, motor, or mixed functions
Central Nervous System (CNS)
- Tracts: Bundles of axons in the CNS, responsible for transmitting information
- Nuclei: Groups of neuron cell bodies in the CNS, responsible for controlling specific functions
- Decussation: The crossing of nerve fibers from one side of the brain or spinal cord to the other
Brainstem
- Medulla oblongata: Controls vital functions like breathing, heart rate, and blood pressure
- Pons: Connects the cerebellum to the rest of the brain, involved in posture and balance
- Midbrain: Involved in visual and auditory reflexes, as well as movement control
Cerebellum
- Responsible for coordination, balance, and motor learning
Cerebrum
- Two hemispheres connected by the corpus callosum, responsible for higher-level functions
- Contains both grey and white matter
Cortex
- Outer layer of the cerebrum, divided into lobes: frontal, parietal, temporal, and occipital
- Each lobe is responsible for specific functions, including sensory perception, motor control, language, memory, and reasoning
Meninges
- Three layers of protective membranes that surround the CNS:
- Dura mater: Outermost layer
- Arachnoid mater: Middle layer
- Pia mater: Innermost layer
Neural Cells
- Stem cells: Undifferentiated cells with the potential to develop into neurons
-
Glial cells: Supporting cells of the nervous system:
-
Macroglia:
- Astrocytes: Provide structural support and regulate blood flow
- Oligodendrocytes: Produce myelin in the CNS
- Schwann cells: Produce myelin in the PNS
- Microglia: Immune cells of the nervous system
-
Macroglia:
Local Potentials
- Occur at the dendrites or soma of neurons, where sensory input is received
- Excitatory local potentials: Depolarize the neuron, making it more likely to fire an action potential
- Inhibitory local potentials: Hyperpolarize the neuron, making it less likely to fire an action potential
Action Potentials
- Triggered responses: Occur when the local potential reaches a threshold
- Generated at the axon hillock due to the presence of voltage-gated channels
- Action potential: A brief electrical impulse that travels down the axon to transmit information
- Ion channels: Opening and closing of ion channels allows for the rapid influx and efflux of ions, creating the action potential
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Description
Explore the key concepts of the nervous system, including the distinctions between direct and indirect control of movement. This quiz covers the structures of the CNS and PNS, as well as functional divisions such as the somatic and autonomic nervous systems.
