The Brain Flashcards
central nervous system
The portion of the nervous system consisting of the brain and spinal cord.
spinal cord
A collection of neurons and supportive tissue running from the base of the brain down the center of the back, protected by a column of bones (spinal column).
peripheral nervous system
All portions of the nervous system outside the brain and spinal cord; it includes sensory and motor nerves.
somatic nervous system
The subdivision of the peripheral nervous system that connects to the sensory receptors and to skeletal muscles; sometimes called the skeletal nervous system.
autonomic nervous system
The subdivision of the peripheral nervous system that regulates the internal organs and glands.
sympathetic nervous system
The subdivision of the autonomic nervous system that mobilizes bodily resources and increases the output of energy during emotion and stress.
parasympathetic nervous system
The subdivision of the autonomic nervous system that operates during relaxed states and that conserves energy.
glia
Cells that support, nurture, and insulate neurons, remove debris when neurons die, enhance the formation and maintenance of neural connections, and modify neuronal functioning.
dendrites
A neuron’s branches that receive information from other neurons and transmit it toward the cell body.
cell body
The part of the neuron that keeps it alive and determines whether it will fire.
axon
A neuron’s extending fiber that conducts impulses away from the cell body and transmits them to other neurons.
myelin sheath
A fatty insulation that may surround the axon of a neuron.
nerve
A bundle of nerve fibers (axons and sometimes dendrites) in the peripheral nervous system.
neurogenesis
The production of new neurons from immature stem cells.
stem cells
Immature cells that renew themselves and have the potential to develop into mature cells; given encouraging environments, stem cells from early embryos can develop into any cell type.
synapse
The site where transmission of a nerve impulse from one nerve cell to another occurs; it includes the axon terminal, the synaptic cleft, and the receptor sites in the membrane of the receiving cell.
action potential
A brief change in electrical voltage that occurs between the inside and the outside of an axon when a neuron is stimulated; it serves to produce an electrical impulse.
neurotransmitter
A chemical substance that is released by a transmitting neuron at the synapse and that alters the activity or a receiving neuron.
endorphins
Chemical substances in the nervous system that are similar in structure and action to opiates; they are involved in pain reduction, pleasure, and memory, and are known technically as endogenous opioid peptides.
hormones
Chemical substances, secreted by organs called glands, that affect the functioning of other organs.