basic unit of structure and function in the nervous system; conducts impulses throughout the nervous system; 3 regions include a cell body, dendrites, axon.
branchlike extensions of the neuron that receive impulses and carry them toward the cell body.
an extension of the neuron that carries impulses away from the cell body and toward other neurons, muscles, or glands.
the small space between a neuron's axon and another neuron's dendrites.
chemicals released from an axon that diffuse across a synapse to the next neuron's dendrites to initiate a new impulse.
Central Nervous System
coordinates all the body's activities.
Peripheral Nervous System
division of the nervous system made up of all the nerves that carry messages to and from the central nervous system.
largest part of the brain, composed of two hemispheres connected by bundles of nerves; controls conscious activities, intelligence, memory, language, skeletal muscle movements, and the senses.
rear portion of the brain; controls balance, posture, and coordination.
part of the brain stem that controls involuntary activities such as breathing and heart rate.
Somatic Nervous System
portion of the nervous system composed of cranial nerves, spinal nerves, and all of their branches; voluntary pathway that relays information mainly between the skin, the CNS, and skeletal muscles.
an automatic response to a stimulus.
Autonomic Nervous System
carries impulses from the CNS to internal organs.
Sympathetic Nervous System
controls many internal functions during times of stress.
Parasympathetic Nervous System
controls many of the body's internal functions when it is at rest; in control when body is relaxed.