chapter four Flashcards
the nervous system (22 cards)
homeostasis
maintenance of an environment of body functions within a certain range (e.g. temperature, blood pressure)
antidiuretic
the suppression of urine production
membrane
a thin, limiting covering of a cell
cell body
the central region of a neuron; which is the control center
dendrites
branchlike structures that extend from the cell body and specialize in receiving signals from other neurons
axon
a thin tube that extends from the cell body and specializes in transmitting signals to other neurons
axon terminals
the end region of the axon
receptors
recognition mechanisms that respond to specific chemical signals
neurotransmitter
chemical messengers released from axon terminals
synaptic vesicles
small bubbles of membrane that store neurotransmitters
myelin
a fatty white substance that is wrapped around portions of the axon
autoimmune disease
a condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue
multiple sclerosis
an autoimmune disease caused by damage to the myelin sheath that wraps axons
blood-brain barrier
the structure that prevents many drugs from entering the brain
semipermeable
allowing some, but not all, chemicals to pass
neurotransmission
the process of transferring information from one neuron to another at a synapse
action potential
the electrical signal transmitted along the axon when a neuron fires
ion channels
pores formed in the cell membrane that allow the passage of ions from one side of the membrane to the other
ion
an atom or molecule that has a net electrical charge because of a difference in the number of electrons and protons
resting potential
the voltage maintained by a cell when it is not generating action potentials
hyperpolarized
when the membrane potential is more negative
depolarized
when the membrane potential is less negative
