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Nodes of Ranvier

Gaps in myelin sheath


Ability of dendrites/axon to respond to a stimulus and create a nerve impulse (electrical signals)

Synaptic Terminals

Storage site for neurotransmitters

Schwann Cells

Speeds up signal transmission; covers the oustide of the axon


Connection between an axon of 1 neuron and dendrites of another

Cell Body

Center of operations that contains organelles (nucleus)


Extensions from cell body that receive information


Tubular component that transmits signal toward another neuron or effector organ


Transmits impulses along the axon

Resting Membrane Potential

Electrical charge difference across the cell membrane caused by unequal distribution of charged ions


Range from -40mv to -75mv; all cells are negatively chaged at rest (polarized)

Ionic Gradients

Electrical attraction of unlike charges; Concentration from an area of [high] to are of [low]

Membrane Permeability

Membrane is much more permeable to K+ than to Na+ most reasponsible for (-) RMP

Sodium Potassium Pump

Responsible for establishing the [gradients] for Na+ & K+ and maintaining the (-) RMP


Inside of the cell becomes less (-) relative to the ouside; -70-->-10 cause by increase of Na+ permeability


Inside of the cell becomes more (-) realitive to the outside (-70-->-110)

Synaptic or Graded Potentials

Localized changes in the membrane potential; cause by ions moving through the membrane; decrease in amplitude as they move

Action Potential

Rapid and large depolarization of the neuron membrane; -70mv--> +30mv; results from summation of many synaptic potentials

Theshold (All-or-None Principle)

Smallest depolarization to produce an action potential; Usually -50mv, requiring a depitarization of +20; depolarization LESS THAN threshold= NO AP

Absolute Refractory

Can not respond to another stimulus when a cell is depolarized

Relative Refractory

Can respond to a new large stimulus

Presynaptic Neuron #1

Carries impulses down the axon to the terminals that contain neurotransmitter (i.e. ACh, NE)

Postsynaptic Neuron #2

Receives impulses when NT attach to receptors on dendrites & cell body (soma)

Synaptic Cleft

Gap between the 2 neurons

Neuromuscular Junction

Area where motor neuron communicates with a muscle fiber

Somatic Motor Function

Voluntary; carries neutral messages from SC to skeletal muscle

Alpha Motor Neuron

Somatic neuron that innervates the skeletal muscle fibers

Motor Unit

Motor neuron, it's axon, and all of the muscle fiber it innervates

Innervation Ratio

Number of muscle fibers/motor neuron

Fine Motor Controls

Eye muscles; low IR (20:1)

Gross Motor Controls

Quads; high IR (2000:1)

Brain Stem

Located inside the base of the skull above the SC; metabolic functions, cardiorespiratory control, some complex reflexes, control of locomotion


Large dome of brain divided into RT & LT hemispheres; organization of complex movement, storage, of learned experiences recieves sensory information

Cerebral Cortex

Outer most layer; contains tightly arranged neuron

Motor Cortex

Portion that handles voluntary movement


Lies behind the pons & medulla; major coordinator of sensory input & provides feedback regarding motion, controls timing and intensity of muscle activity

Spinal Cord

Relays information between the CNS & PNS; controls and intergrates simple and complex spinal reflexes

Autonomic Nervous System

Involuntary-PNS; controls the body's internal environment by innervation effector organs (smooth muscle, cardiac glands)

Sympathetic Division

Tends to active organ increase HR; release NT- norepinephrine at organ

Parasympathetic Division

Tend to inhibit organ decrease HR; release NT- ACh at organ

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