40 terms

Nervous System

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