chapter 48 Flashcards
what are neurons?
the nerve cells that transfer information within the body
what is the significance if the cell body?
is where most of the organelles are located
what are dendrites?
highly branched extensions of a neuron
what is an axon?
an extension that transmits signals to other cells
what is an axon hillock?
cone shaped base of an axon, where signals travel down
what is a synapse?
a junction between cells
what is the synaptic terminal?
the part of each axon branch that forms a specialized junction
what are neurotransmitters?
chemical messengers
what is a presynaptic cell?
neuron where info is coming from
what is a postsynaptic cell?
gland/muscle where info is going to
long distance transfer is
electric
short distance transfer is
chemical
what is the glia?
surround neuron, regulate fluid, most abundant cell type in central nervous system
what are the 3 stages of information processing?
sensory input, integration, and motor output
what are sensory neurons?
transmit information about external stimuli
what are interneurons?
form the local circuits connecting neurons in the brain
what are motor neurons?
transmit signals to muscle cells, causing them to contract
what s the central nervous system?
neurons that carry out integration
what is the peripheral nervous system?
neurons that carry information into and out of the CNS
what is membrane potential?
ions are unequally distributed causing the cell to be negatively charged. attraction of opposite charges across the plasma membrane is a source of potential energy
what is resting potential?
potential of a neuron that is not sending a signal
what is a sodium-potassium pump?
uses ATP hydrolysis to actively transport sodium out of the cell and potassium into the cell. generates a net export of positive charge.
why are sodium and potassium important in resting potential?
ions each have a concentration gradient across the plasma membrane of a neuron
what are gated ion channels?
ion channels that open/close in response to stimuli
what are the 3 types of gated ion channels?
chemical, mechanical, and voltage
what is hyperpolarization?
increased magnitude of the membrane potential that makes the membrane more negative
how does hyperpolarization work?
ions flow across membrane trough gated ion channels (potassium channels)
what is depolarization?
a reduction in the magnitude of the membrane potential, makes the inside less negative (sodium channels)
what is the refractory period?
recovery time for membrane to be ready for the next stimulus
what is a graded potential?
de/hyper polarization depends on strength of stimulus. amp is correlated to how powerful the stimulus is
what is an action potential?
always leads to depolarization, massive change in membrane voltage. can regenerate, god for long distance signals
how is action potential positive feedback?
sodium makes more channels to open
what is a threshold?
when depolarization increases the membrane voltage to a particular value
what is epilepsy?
affects sodium channels in brain makes nerves fire too much-> channels overexcited
how is width of the axon related to the speed of action potential?
more width, more speed
rate of conduction of action potential governs what?
speed of an animals response
what is the myelin sheaths?
electrical insulation that surrounds vertebrate axons
what are oligodendrocytes?
glia that produced myelin sheaths in CNS
what are schwann cells?
glia that produces myelin sheaths in the PNS
what are the nodes of ranvier?
voltage-gated sodium channels restricted to gaps in the myelin sheaths
what is multiple sclerosis?
autoimmune disease degrading myelin sheets
what is guillain-barre syndrone?
damages nerve cells, death from lack of air.
what is X-ALD?
geenetic disease where myelin sheets don’t develop
what is progressive multifocal leukoencephalopathy?
virus, possibly fatal
what is central pontine myelinolysis?
damage in myelin sheaths in brain, caused by diet, sodium levels decrease
what are electrical synapses?
synapses that contain gap junstions that allow electrical current to flow directly from 1 neuron to another
what are chemical synapses?
involve the release of a chemical neutotransmitter by the presynaptic neuron
what is the presynaptic neuron?
releases chemical neurotransmitter
what are synaptic vesicles?
packages ofneutrotransmitter in multiple membrane-encolsed compartments
what are synaptic clefts?
separates pre/post synaptic cell
what does signaling depend on?
type of neurotransmitter released at the presynaptic and the receptor produced at the postsynaptic membrane
when does a signal end?
when the neurotransmitter is cleared from the synaptic cleft
what is acetylcholine?
triggers voluntary muscle contractions, heartbeat, and excretion of certain hormones. found in CNS and PNS. many toxins affect it, change its transmission by inactivating/ hyperactivating muscles
what is glutamate?
the neurotransmitter at the neuromuscular junction in invertebrates
what is GABA?
mood modulator, blocks nerve impulses in the brain, works opposite of glutamate, tells cells not to fire. low levels cause cells to get overexcited.
what is valium?
brings GABA back into brain
what are biogenic animes?
neurotransmitters synthesized from amino acids
what is dopamine?
both excitatory and inhibitory neurotransmitter
what is seratonin?
inhibitory, regulates mood
what is epinephrine?
fight or flight hormone, produced in adrenal gland ,
what is norepinephrine?
noaderenaline
what are neuropeptides (endorphins) ?
natural pain relievers
what role does carbon monoxide play in neurotrasmitters?
regulates the release of hormones from hypothalamus
