Nervous System
● extensive network of specialized cells that carries info to and from all parts of the body
● Central
○ Spinal cord
○ Brain
● Peripheral
○ Autonomic
■ regulate automatic systems
■ Parasympathetic
● Maintain body functions under ordinary
■ Sympathetic
○ Somatic
Cells of the Nervous System
● Neurons
○ Receive and send messages within nervous system
○ Afferent neurons-sensory
■ Approaching nervous system
○ Efferent neurons-motor
■ Nervous system to muscles and glands
○ Interneurons-connect afferent to efferent
■ Makes up spinal cord and brain
● Glial cells
○ Partner cells
○ Critical to proper function of neurons
○ Functions
■ Structural support
■ Nutrient delivery
■ Production of myelin
● insulation
● protection
○ Speed of neural communication
● Remove waste and dead neurons
● Develop new neurons
Neuron Structure
● 1. Dendrites
, 2
● 2. Soma- cell body
● 3. Axon- carries signal from one end to another
● 4. Axon terminals/ synaptic knobs- signal exits
● Communication of neurons
○ Within: electrical
○ Between: chemical
■ Involves neurotransmitters
Communication of neurons: Within
● Resting potential
○ not firing a neuron
● Action potential
○ the release of neural impulse
● Resting-state
○ More K potassium inside
○ more Na sodium outside
○ Inside - , Outside +,
○ Leak channel- passive channel
○ Sodium Potassium pump- pumps 2 K
back into the cell, kicks out 3 Na
● Electrical charge within Neuron
● Fires at full strength or not at all
● Action potential
○ Sodium moves inside the side
○ Inside +, outside -
● Return to resting state
○ Inside - , Outside +,
○ Voltage-gated Sodium gates close
○ Voltage-gated potassium gates open
○ Hyperpolarization- refracturing period, becomes more negative
● Sodium Potassium Pump maintains relative negative state
● Interfering with cell signaling: local anesthetics
○ Dentist and cavities
○ LA bind to gate and blocks the channel
○ Action potential can’t fire
● Saltatory Conduction
○ Action potentials occur only at unmyelinated spaced on the axon ( nodes of
Ranvier), signal jumps from node to node
○ Benefits
■ Speed up transmission
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