Unit 2 Flashcards
Central Nervous System (CNS)
The brain and spinal cord
Peripheral Nervous System (PNS)
Connects to CNS to the limbs and organs, essentially serving as a communication relay going back and forth between the brain and the extremities
Somatic Nervous System
The division of the PNS that controls the body’s skeletal muscles. Also known as the skeletal nervous system.
Autonomic Nervous System
The part of the PNS that controls the glands and the muscles of the internal organs. Controls the sympathetic and parasympathetic nervous systems
Sympathetic Nervous System
“Fight or flight or freeze” the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations
Parasympathetic Nervous System
“Rest and digest” the division of the autonomic nervous system that calms the body, conserving its energy
Sensory neurons
Neurons that carry incoming information from the sensory receptors to the brain and spinal cord
Interneurons
neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and the motor outputs
Motor neurons
Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands
Soma (cell body)
The neuron’s life support center that also produces neurotransmitters
Dendrite
The bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body
Axon
The extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons, muscles, or glands
Myelin sheath
A layer of fatty tissue that covers the axon which aides in the speed of neural impulses; the thicker the myelin sheath, the faster the impulse
Nodes of Ranvier
Spaces between the myelin
Schwann Cell
Produces myelin
Action potential
A neural impulse; a brief electrical charge that travels down an axon
Ions
Electrically charged atoms
Resting potential
A fluid interior of a resting axon has an excess of negatively charged ions, while the fluid outside the axon membrane has more positively charged ions
Selectively permeable
The axon’s surface is very selective about what it allows in
Polarized
During the resting state of a neuron when the outside is now positively charged and the inside is now negatively charged
Depolarized
Axon is no longer at resting potential; outside is now negatively charged and inside is now positively charged
Refractory period
Resting state after firing in which the neuron goes back to its polarized resting state
Excitatory
Accelerates neuron’s firing speed
Inhibitory
Slows neuron’s firing speed