Anatomy: Ch. 12 Nervous System Flashcards

Nervous System Overview

• Master control and communication system with three primary functions: Sensory Input, Integration, and Motor Output.

Functions of the Nervous System

• Sensory Input: Receptors detect changes inside and outside the body, relaying information to the integrating center.
• Integration: Processing and interpreting sensory information to make decisions.
• Motor Output: Initiating responses by activating effector organs, such as muscles and glands.

Central and Peripheral Nervous Systems

• Central Nervous System (CNS): Comprised of the brain and spinal cord; serves as the command center for processing information.
• Peripheral Nervous System (PNS): Includes nerves extending from the brain and spinal cord, linking all body regions to the CNS.

Sensory and Motor Pathways

• Sensory Afferent: Nerve fibers that carry signals from sensor receptors to the CNS.
• Motor Efferent: Nerve fibers that transmit signals away from the CNS to muscles and glands.

Body Regions

• Somatic Body Region: Comprises skin, skeletal muscle, and bones.
• Visceral Body Region: Includes internal organs such as the digestive system, lungs, heart, and bladder.

Sensory Information

• Visceral Sensory: General senses like stretch, pain, temperature, nausea, and hunger; special senses include taste.
• General Somatic Senses: Cover touch, pain, pressure, and temperature, with receptors widely distributed.
• Somatic Proprioceptive Senses: Detect stretch in tendons and muscles, providing information about body position and movement.

Nervous System Subdivisions

• Visceral Motor: Regulates smooth and cardiac muscle contraction as well as glandular secretion; constitutes the autonomic nervous system.
• Autonomic Nervous System: Manages involuntary functions of visceral organs.

Neurons and Support Cells

• Nervous Tissue: Composed of dense networks of cells, primarily neurons and neuroglial (support) cells.
• Neurons: Specialized cells that transmit electrical signals, characterized by their longevity, inability to divide, and high metabolic demand.
• Support Cells: Non-excitable neuroglial cells that surround and support neurons.

Neuron Structure

• Soma (Cell Body): Contains the nucleus and typical organelles; mostly located in the CNS for protection.
• Chromatophilic Bodies: Clusters of rough endoplasmic reticulum and ribosomes involved in membrane renewal.
• Neurofibrils: Intermediate filament bundles forming a network that supports the neuron structure.
• Dendrites: Branching extensions that transmit electrical signals towards the soma, acting as receptive sites.
• Axons: Singular long extensions that carry impulses away from the soma, lacking protein synthesis capabilities.

Axon and Impulse Transmission

• Axon Collaterals: Infrequently branching processes that extend from the length of the axon.
• Telodendria: Numerous branching at the axon's end.
• Axon Terminals: Knob-like endings, also referred to as end bulbs or boutons, essential for neurotransmitter release during nerve impulses.
• Nerve Impulse (Action Potential): Generated at the axon's initial segment and propagated along the axon, culminating in neurotransmitter release at terminals.