PHYSIOEX Lab 3 - Experiments 1-9 Flashcards
nervous system contains two types of cells
neurons and neuroglia (or glial cells)
the receptor potential can trigger another electrical signal (called action potential) which travels where?
along the membrane of the sensory neurons axon to the brain
Action potential causes the release of what
chemical neurotransmitters
T/F: interneurons respond to chemical neurotrasmitters released by other neurons
TRUE
Neuron has three function regions:
receiving region
conducting region
output region or secretory region
cell body and dendrites of interneurons receive stimulation by neurotransmitters at structures called? and produce what?
chemical synapses and produce synaptic potentials
the conducting region is usually an _______ which ends in an output region where neurotransmitter is released
axon
define neuron
single cell surrounded by continous plasma membrane
each region contains distinct membrane proteins that provide the basis for the function differences
Dscribe the receiving end of the neuron:
has receptor proteins and proteins that generate the receptor potential
Describe the conducting region of the neuron
has proteins that generate and conduct action potentials
describe the output region of the neuron
has proteins to package and release neurotransmitters
T/F: ions cannot easily pass through the lipid bilayer of the plasma membrane and must pass through ion channels
TRUE
Describe membrane potential:
it is more common to measure the potential difference, or voltage, across the membrane this membrane voltage is usually called the membrane potential
what are the units of the membrane potential called?
millivolts (mV)
Describe polarized:
plasma membrane can store a charge and has a relatively positive side and a relatively negative side. the membrane is polarized.
what occurs when two sides (intracellular and extracelluar) are connected through open ion channesl?
current in the form of ions can flow in or out across the membrane and thus change the membrane voltage.
For many neurons, ____ and ____ are the most important ions
Na+ and K+
What is the approximate concentration of K+ inside a typical cell (intracellular concentration
150mM
What is the approximate concentration of K+ outside a cell (extracellular concentration
5mM
What is the approximate concentration of Na+ inside a cell (intracellular concentration
5mM
What is the approximate concentration of Na+ outside a cell (extracellular concentration
150mM
the sensory receptor is the ____________________________________
receiving end of a sensory neuron
the sensory receptor has receptor proteins that general a signal called the
receptor potential
describe sensory transduction:
the energy in the stimulus is changed into an electral response that involves the opening or closing of a membrane ion channel
describe depolarization
if the response (receptor potential) is a change in membrane potential from the negative resting potential to a less negative level
which of the following is a sensory modality:
touch, smell, sight, pain
which of the following is a sensory stimulus
pressure, chemical odorants, light
which of the ofllowing is true of the response of a sensory neuron to the appropriate sensory stimulus
it can be called a receptor potential, it is graded potential, it is a change in the resting membrane potential
Describe Axon
long, thin structures that conduct a signal called the action potential
in a typical multipolar neuron the axon extends from the cell body at a regionaled called:
axon hillock
in a myelinated axon, the first region is called the ______
initial segment
an action potential is usually initiaated at the junction of the axon hillock and the initial segment; therefore, this region is called
trigger zone
in a sensory neuron, the depolarizing receptor potential spreads _______ to the __________ and produces the depolarization needed to evoke the _________
passively
axon hillock
action potential
once an action potential is generated, it is regenerated down the membrane of the axon. the action potential is________________ or conducted, down the axon
propagated
a nerve is _
a bundle of axons
axons are
long, thin structures that extend from a neuronal cell body
which of the following is easier:
extracellular recordings of the action potential
an action potential is usually initiaed in an axon at or near:
the axon hillock, the initial segment, the trigger zone
the initiation of an action potential in a sensory neron in the body normally:
follows a sufficiently large depolarizing receptor potential
voltage-gated sodium channels open when
the membrane depolarizes
each _____ channel that opens allows ______ to diffuse in the cell down their electrochemical gradient
sodium channel
Na+ ions
voltage-gated Na+ channels are membrane channels that open:
when the membrane depolarizes
when open, Na= channels allow:
Na+ ions to diffuse into the cell
which of the following is true of an action potential:
the generation of an action potential uses voltage-gated Na+ channels, an action potential is a large, all or none change in membrane potential
which of the following can reduce the likelihood of an action potential:
TTX, lidocaine, creasing the leak of K+ from a cell
voltage-gated sodium channels in the plasma membrane of the excitable cell ______ when the membrane ________
open
depolarizes
which of the following occurs after the peak of the action potential:
the membrane repolarizes
voltage-gated K+ channels open
some voltage-gated Na+ channels inactivate
which is mean by Na+ channel inactivation
the Na+ channels no longer allows Na+ ions to pass through
what happens when voltage-gated K+ channels open:
K+ ions can diffuse out of the cell
the membrane repolarizes from the peak of the action potential
it becomes harder for a subsequent stimulus to depolarize the membrane to threshold.
it is harder to generate a second action potential soon after the first action potential because
some voltage-gated Na+ channels are inactivated
voltage-gated K+ channels have opened
the efflux of K+ ions opposes a depolarization towartd threshold
the time after an action potential when a second action potential cannot be generated no matter how intentse the stimulus is called the
absolute refractory period
the time after an action potential when a second action potential can be generated on:
if the stimulus intensiyt is increased is called the relative refractory period
the term frequency refers to
the number of action potentials per second
propagation/conduction occurse because
there are voltage-gated sodium and potassium channels located along the axon and the large depolarzation that constitues the action potential easily brings the next gion of the axon to threshold
_________________can be easily calculated by knowing both the distance the action potential travels and the amount of time it takes
conduction velocity
velocity has the units of distance per time, typically ______________
meters/second
what parameters influence the conduction velocity in an axon?
axon diameter and amount of myelination
myelination refers
to a special wrapping of tthe membrane from glial cells around the axon
in the central nervous systems: ________ are the glial that wrap around the axon
oligodendorcyts
in the peripheral nervous sytem: the ________ cells are the glial that wrap around the axon
schwann cells
myelin sheaths are seperated by gaps called
nodes of ranvier
an action potential can be propagated along an axon because there are
voltage-gated channels in the membrane
the units of conduction velocity are
meters/second
which of the following will affect axonal conduction velocity:
both the diameter of the axon and the amount of myelination
which of the following describes an A fiber
large diameter, heavily myelinated
which of the following describes a C fiber
small diameter, unmyelinated
At the end of each axon brach there is a region called the
axon terminal
describe the function ofthe axon terminal
to release packets of chemical neurotransmitters from small intracellular membrane-bound vesicles, called synaptic vesicles
neuron releasing chemicals are released by exocytosis and diffuse across a small extracellular space called
synapic gap or synaptic deft
region where the neurotransmitter is released from one neuron and binds to a receptor on a target cell is called
chemical synapse
the change in membrane potential of the target is called a
synaptic potential or postsynaptic potential
exocytosis of synaptic vesicles is normally triggered by the
increase in calcium ions in the axon terminal
_____________ enters from the outside the cell through membrane calcium channels that are open dby the depolarization of an action potential
calcium enters
the end of the axon where it contacts a target cell is called the
axon terminal
neurotransmitter is released into the synapic gap by
exocytosis
exocytosis of neurotransmitter from the axon terminal is triggered by
an increase in the intracellular concentration of Ca2+
neurotransmitter released into the synaptic gap reaches the target cell by
diffusion
at the target, neurotransmitter
binds to receptor proteins
causes membrane channels to open or close
causes a change in membrane potential
Excitatory postsynapic potential is
graded amplitude, depending on teh amount of neurotransmitter and the number of channels it opens
sensory neurons respond to an appropriate sensory stimulus with a change in membrane potential that is
graded with the stimulus intensity
if the depolarization that reaches the axon is large and suprathreshold, the result in the axon is:
action potential at higher frequency
at the axon terminal, each action potential causes the release of neurotransmitter. this neurotransmitter diffuses to the receiving end of an interneuron, where it binds to receptors and causes:
ion channels to open, so that the receiving end of the interneuron depolarizes
interneurons respond to chemical stimulation with a change in membrane potential that is
graded with the stimulus intensity
