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Questions and Answers
The main command center of the nervous system is the ______.
brain
The ______ division carries information to the central nervous system.
sensory
The ______ nervous system controls involuntary actions.
autonomic
Neuroglia are able to ______, while neurons cannot.
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The response activated by integrated stimuli is called ______ output.
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Astrocytes provide structural ______
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Ependymal cells line the ______ of the brain and central canal of the spinal cord
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Microglia protect the CNS from ______
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Schwann cells form myelin sheath in the ______ nervous system
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Dendrites conduct impulses ______ the cell body
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Study Notes
Functions of the Nervous System
- Maintains homeostasis through electrical signals.
- Facilitates sensation and higher mental functions, including emotions.
- Controls and activates muscles and glands.
Roles of the Nervous System
- Sensory Input: Gathers information about internal and external stimuli.
- Integration: Processes and interprets sensory information to determine action.
- Motor Output: Executes responses to stimuli by activating muscles or glands.
Structural Classification of the Nervous System
- Central Nervous System (CNS): Comprises the brain and spinal cord; located in the dorsal cavity; serves as the command center for processing information.
- Peripheral Nervous System (PNS): Consists of nerves outside the CNS; facilitates communication between the CNS and the body.
Functional Classification of the PNS
- Sensory (Afferent) Division: Carries information to the CNS.
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Motor (Efferent) Division: Carries impulses away from the CNS; divided into:
- Somatic Nervous System: Voluntary control over skeletal muscles.
- Autonomic Nervous System: Involuntary control over smooth muscles and glands.
Neuroglia vs. Neurons
- Neuroglia can divide; neurons cannot.
- Most brain tumors (gliomas) originate from neuroglial cells.
Support Cells in the CNS
- Astrocytes: Provide structural support, regulate neuronal signaling, assist in repair.
- Ependymal Cells: Line brain ventricles and spinal canal; produce and circulate cerebrospinal fluid (CSF).
- Microglia: Act as phagocytes to protect against infection.
- Oligodendrocytes: Form the myelin sheath in the CNS.
Support Cells in the PNS
- Schwann Cells: Produce myelin sheaths around peripheral nerves.
- Satellite Cells: Offer support and nutrition to neurons and protect from toxins.
Neuron Anatomy
- Neurons consist of a cell body (with nucleus) and processes (dendrites and a single axon).
- Dendrites convey impulses toward the cell body; axons transmit impulses away.
Nerve Impulses and Axon Terminology
- Axonal terminals contain neurotransmitter vesicles, separated from adjacent neurons by the synaptic cleft.
- Synapse: The junction where neuron communication occurs.
Nerve Fiber Coverings
- Schwann Cells: Myelinate peripheral axons.
- Nodes of Ranvier: Gaps in myelin sheaths that facilitate faster signal transmission.
Neuron Cell Body Location
- Most neurons reside in the CNS, forming gray matter (cell bodies and unmyelinated fibers) and white matter (myelinated axons).
- Nuclei: Clusters of cell bodies within the CNS white matter.
- Ganglia: Collections of cell bodies in the PNS.
Classification and Function of Neurons
- Sensory Neurons: Transmit impulses from sensory receptors to the CNS.
- Motor Neurons: Convey impulses from the CNS to muscles and glands.
- Interneurons: Connect sensory and motor neurons within the CNS.
Physiology of Neurons
- Irritability: Neurons can respond to stimuli.
- Conductivity: Ability to transmit impulses.
- Neurons at rest have a polarized membrane.
Starting a Nerve Impulse
- Depolarization: Stimulus triggers sodium ions to enter the neuron, initiating an action potential.
Action Potential Propagation
- If initiated, the action potential spreads along the axon.
- Sodium influx followed by potassium efflux repolarizes the membrane.
Nerve Impulse Propagation
- Myelinated fibers transmit impulses more rapidly due to saltatory conduction.
Synaptic Transmission
- Impulses bridge the synapse through neurotransmitter release, affecting receptor-stimulated dendrites of adjacent neurons.
Reflex Arc
- Reflexes are rapid, involuntary responses; the reflex arc provides a direct route from sensory neurons, through interneurons, to effectors.
Central Nervous System Development
- CNS originates from the embryonic neural tube, evolving into the brain and spinal cord.
Brain Structure Regions
- Major parts are the cerebral hemispheres, diencephalon, brain stem, and cerebellum.
Cerebral Hemispheres
- Consist of left and right halves; contain more than 50% of brain mass.
- Structurally defined by gyri (ridges) and sulci (grooves).
Lobes of the Cerebrum
- Cerebrum is divided into frontal, parietal, occipital, and temporal lobes, each with specific sensory and motor functions.
Specialized Areas of the Cerebrum
- Regions for speech, language comprehension, and general interpretation.
Cerebral Layers
- Gray Matter: Outer layer that initiates thoughts and actions.
- White Matter: Composed of myelinated axons, facilitating impulse conduction.
Diencephalon Structure
- Comprised of the thalamus, hypothalamus, and epithalamus; functions in sensory relay, homeostasis, and endocrine regulation.
Brain Stem Components
- Includes the midbrain, pons, and medulla oblongata; controls vital functions such as heart rate and breathing.
Cerebellum Function
- Coordinates balance and voluntary movements through its convoluted surface structure.
Protection of the CNS
- Encased by scalp, skull, and vertebral column; protected by meninges and cerebrospinal fluid.
Meninges Structure
- Dura Mater: Tough outer layer.
- Arachnoid Layer: Web-like middle layer.
- Pia Mater: Thin inner layer adhering to the brain.
Cerebrospinal Fluid
- Provides cushioning for the brain; composition changes can indicate medical conditions.
Blood-Brain Barrier
- Comprised of tightly sealed capillaries; selectively excludes harmful substances while allowing some essential nutrients to pass.
Spinal Cord Characteristics
- Extends from the medulla to the T12 region; serves as a conduit for nerve impulses and spinal reflex centers; contains 31 pairs of spinal nerves.
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Description
Explore the vital functions of the nervous system, including its role in maintaining homeostasis, providing sensation, and controlling muscle movements. This quiz delves into sensory input, integration, and the resulting motor output. Test your understanding of how these elements work together to process information and react to stimuli.
