Ch. 11 Fundamentals of the Nervous System and Nervous Tissue Flashcards
The master controlling and communicating system of the body
Nervous system
Gathered information from sensory nerves
Sensory input
The interpretation of sensory input and decision on what should be done at each moment
Integration
A response carried out by the muscles and glanes
Motor output
Consists of the brain and spinal cord and is the integrating and control center of the nervous system. It interprets sensory input and dictates motor output based on reflexes, current conditions, and past experience
Central nervous system (CNS)
The part of the nervous system that is outside the CNS and consists mainly of nerves and ganglia
Peripheral nervous system (PNS)
A division of the PNS that consists of nerve fibers that convey impulses to the central nervous system from sensory receptors located throughout the body
Sensory (afferent division)
Fibers that convey impulses from the skin, skeletal muscles, and joints
Somatic sensory fibers
Fibers that transmit impulses from the visceral organs
Visceral sensory fibers
A division of the PNS that transmits impulses from the CNS to effector organs, which are the muscles and glands
Motor (efferent division)
A further division of the motor division that is composed of somatic motor nerve fibers that conduct impulses from the CNS to skeletal muscles
Somatic nervous system (voluntary nervous system)
A further division of the motor division that consists of visceral motor nerve fibers that regulate the activity of smooth muscles, cardiac muscles, and glands
Autonomic nervous system (involuntary nervous system)
Supporting cells that surround and wrap the more delicate neurons
Neuroglia
Nerve cells that are excitable and transmit electrical signals
Neurons
Smaller cells that support and maintain neurons
Neuroglia
A type of PNS neuroglia that surrounds neuron cell bodies
Satellite cells
A type of PNS neuroglia that surround all nerve fibers and form myelin sheaths around the thicker nerve fibers
Schwann cells
Bundles of intermediate filaments that are important in maintaining cell shape and integrity
Neurofibrils
Clusters of cell bodies in the CNS
Nuclei
Clusters of cell bodies that lie along the nerves in the PNS
Ganglia
Bundles of neuron processes in the CNS
Tracts
Bundles of neuron processes in the PNS
Nerves
Short, tapering, diffusely branching extensions of motor neurons that convey incoming messages toward the cell body
Dendrites
Long part of a neuron that can vary in length and generates nerve impulses and transmits them away from the cell body along the plasma membrane
Axon
Cone-shaped part of neuron where the axon arises from
Axon hillock
Occasional branches extending from the length of the axon
Axon collaterals
Branches at the end of the axon that contain distal endings
Terminal branches and Axon Terminals
Movement away from the cell body
Anterograde movement
Movement towards the cell body
Retrograde movement
A whitish, fatty, segmented substance that surrounds a nerve fiber (long axon). It protects and electrically insulates the fibers and increases the transmission speed of nerve impulses
Myelin sheath
Gaps in the myelin sheath that occur at regular intervals along a myelinated axon
Myelin sheath gaps or nodes of Ranvier
Regions of the brain and spinal cord containing dense collections of myelinated fibers
White matter
Regions that contain mostly neuron cell bodies and nonmyelinated fibers
Gray matter
A type of neuron that has 3 or more process, makes up 99% of neurons and are either interneurons or motor neurons
Multipolar neurons
A type of neuron that has 2 processes, usually sensory neurons, and are rare; only found in some organs
Bipolar neurons
A type of neuron that has a single short process that emerges from the cell body and divides into proximal and distal branches. They are mostly found in ganglia in the PNS and function as sensory neurons
Unipolar neurons
The type of neuron that transmits impulses from sensory receptors in the skin or internal organs toward or into the central nervous system
Sensory or afferent neurons
The type of neuron that carries impulses away from the CNS to the effector organs of the body1
Motor or efferent neurons
Lies between motor and sensory neurons in neural pathways and shuttle signals through CNS pathways where integration occurs
Interneurons (association neurons)
The measure of potential energy generated by separated electrical charges
Voltage
The difference in charge between two points that measures voltage
Potential difference
The flow of electrical charge from one point to another
Current
The hindrance to charge flow provided by substances through which the current must pass
Resistance
Gives the relationship between voltage, current, and resistance.
Ohm’s law
The channels that open when the appropriate chemical binds
Chemically gated channels (ligand-gated channels)
The channels that open and close in response to changes in the membrane potential
Voltage-gated channels
The channels that open in response to physical deformation of the receptor (sensory receptors for touch and pressure)
Mechanically gated channels
Ions move along what gradient when they diffuse passively from an area of their higher concentration to an area of lower concentration
Concentration gradient
Ions move along what gradient when they move toward an area of opposite electrical charge
Electrical gradients
Together, electrical and concentration gradients constitute… It determines which way ions flow
Electrochemical gradient
The potential difference in a resting neuron
Resting membrane potential
It stabilizes the resting membrane potential by maintaining the concentration gradients for sodium and potassium
Sodium-potassium pump (Na+ -K+ ATPase)
Incoming signals operating over short distances. Short-lived, localized changes in membrane potential
Graded potentials
Long-distance signals of axons
Action potentials
A decrease in membrane potential (the inside of the membrane becomes less negative than the resting potential)
Depolarization
An increase in membrane potential (the inside of the membrane becomes more negative than the resting potential)
Hyperpolarization
When the receptor of a sensory neuron is excited by some from of energy
Receptor potential (generator potential)
When the current dies out within a few millimeters of its origin it is said to be…
Decremental
