Chapter 3 Section 1 Flashcards
nervous system
a collection of hundreds of billions of specialized and interconnected cells through which messages are sent between the brain and the rest of the body.
central nervous system
made up of the brain and the spinal cord
peripheral nervous system
the neurons that link the CNS to our skin, muscles, and glands
endrocrine system
the chemical regulator of the body that consists of glands that secrete hormones
neuron
a cell in the central nervous system whose function it is to receive and transmit information
soma
contains the nucleus of the cell and keeps the cell alive
dendrite
collects information from other cells and sends the information to the soma;
axon
transmits information away from the cell body toward other neurons or to the muscles and glands. end of an axon has a “terminal button”
myelin sheath
a layer of fatty tissue surrounding the axon of a neuron that both acts as an insulator and allows faster transmission of the electrical signal
neuron signaling
electrochemical signaling. electric charge moves through the neuron. chemicals between neurons. signal retrieved by dendrites, passed as electrical to soma, then onto axon and terminal buttons. release neurotransmitters (chemicals that cross synapses)
synapses
space between terminal button of one neuron and dendrites of others. ingenious system because it lets one axon comm with hundreds of dendrites
resting potential
a state in which the interior of the neuron contains a greater number of negatively charged ions than does the area outside the cell
neurotransmitter
a chemical that relays signals across the synapses between neurons. lock and key of sender and receiver.
excitatory or inhibitory
traits of neurotransmitter; making cell more or less likely to fire.
action potential
change in electrical charge that occurs in a neuron when a nerve impulse is transmitted. operates in “all-or-nothing” manner:
nodes of ranvier
breaks sausage-like sections of myelin sheath on axon. divides segments as electrical signals travel down the line.
refractory period
brief time after firing of the axon in which the axon cannot fire again because neuron has not yet returned to its resting potential
reuptake
when neurotransmitters that are in the synapse are reabsorbed by the terminal buttons, ready to be released again when neuron fires
anagonist
a drug that has chemical properties similar to a particular neurotransmitter and thus mimics the effect of the neurotransmitter
antagonist
a drug that reduces or stops the normal effect of a neurotransmitter. binds to dendrite receptor sites, blocking neurotransmitter
Acetylcholine
A common neurotransmitter used in the spinal cord and motor neurons to stimulate muscle contractions. It’s also used in the brain to regulate memory, sleeping, and dreaming.
Alzheimer’s disease is associated with an undersupply of acetylcholine. Nicotine is an agonist that acts like acetylcholine.
Dopamine
Involved in movement, motivation, and emotion, Dopamine produces feelings of pleasure when released by the brain’s reward system, and it‘s also involved in learning.
Schizophrenia is linked to increases in dopamine, whereas Parkinson’s disease is linked to reductions in dopamine (and dopamine agonists may be used to treat it).
Endorphins
Released in response to behaviors such as vigorous exercise, orgasm, and eating spicy foods.
Endorphins are natural pain relievers. They are related to the compounds found in drugs such as opium, morphine, and heroin. The release of endorphins creates the runner’s high that is experienced after intense physical exertion.
GABA (gamma- aminobutyric acid)
The major inhibitory neurotransmitter in the brain.
A lack of GABA can lead to involuntary motor actions, including tremors and seizures. Alcohol stimulates the release of GABA, which inhibits the nervous system and makes us feel drunk. Low levels of GABA can produce anxiety, and GABA agonists (tranquilizers) are used to reduce anxiety.
