physiology unit three exam
special summation refers to...
multiple graded potentials arriving at one location simultaneously.
compared to the outside surface, the inside of a resting cell membrane is.....
negatively charged
the primary problem in hyperkalemia is.....
neurons are hyperexcitable because their resting potential is closer to threshold AND neurons respond too quickly to smaller graded potentials.
the following are the main steps in the generation of action potential... 1. sodium channels are inactivated 2. voltage-regulated potassium channels open and potassium moves out of the cell, initiating repolarization 3. sodium channels regain their normal properties 4. a graded depolarization brings an area of an excitable membrane to threshold 5. a temporary hyperpolarization occurs 6. sodium channel activation gate opens 7. sodium ions enter the cell and further depolarization occurs The proper sequence of these events is:
- a grated depolarization brings an area of an excitable membrane to threshold. - sodium channel activation gate opens - sodium ions enter the cell and further depolarization occurs -sodium channels are inactivated - voltage-regulated potassium channels open and potassium moves out of the cell, initiating repolarization - a temporary hyperpolarization occurs - sodium channels regain their normal properties.
-----------------------------------------
---------------------------------------
-----------------------------------------
-----------------------------------------
the resting membrane potential in a typical nerve cell is approximately...
-70mV
graded potentials...
-are variable-strength signals -travel over short distances -lose strength as they travel through the cell -are used for short-distance communication.
graded potentials may.....
-initiate an action potential -depolarize the membrane to the threshold voltage -hyperpolarize the membrane -be called EPSPs or IPSPs
..............................................................
........................................................................
resting cell membranes are most permeable to __________.
K+
____________ released by all autonomic preganglionic neurons.
acetylcholine
__________ postganglionic sympathetic neurons secrete ____________ onto their target cells. - all ; norepinephrine - most ; norepinephrine - all ; acetylcholine
all ; acytylcholine
the all-or-none principle states that...
all stimuli great enough to bring the membrane to threshold will produce action potentials of identical magnitude.
which of the following glial cells become part of the blood-brain barrier?
astrocytes
Action potentials are primarily associated with the membranes of...
cell bodies only
oxygen
chemoreceptor
pH
chemoreceptor
the pattern of synaptic connectivity where a large number of presynaptic neurons provide input to a single postsynaptic neuron, is known as....
convergence
to -50 mV from resting potential
depolarization
the enteric nervous system is a network of neurons that function in controlling...
digestion
when comparing action potentials to graded potentials, an/two important distinguishing characteristic/s is/are.....
graded potentials can undergo summation AND that the rate of action potentials is limited by the refractory period.
convergence describes.....
how multiple primary sensory neurons synapse on a single secondary neuron.
to -90mV from resting potential
hyperpolarization
if the ECF K+ concentration increases from 3mM to 5mM, what happens to the resting potential of cells?
it becomes less negative (ex: from -70mV to -60mV)
what happens to the resting membrane potential of a cell if the extracellular K+ concentration increases?
it becomes more positive
the purpose of the blood-brain barrier is to _____________.
keep potentially harmful substances in the blood away from the brain.
pressure
mechanoreceptor
stretch
mechanoreceptor
toms father suffers a stroke that leaves him partially paralyzed on his right side. What type of glial cell would you expect to find in increased numbers in the damaged area of the brain that is affected by the stroke?
microglial
nociceptors are responsible for the perception of...
pain and itch
the afferent and efferent axons together form the...
peripheral nervous system
which of the following has its cell body in the ganglion?
postganglionic neuron
which of the following lists the parts of a reflex arc in the correct sequence?
receptor, sensory neuron, interneuron, motor neuron, effector.
to -70mV from -50mV
repolarization
during the rising phrase of the action potential ....
sodium moves down both a concentration and electrical gradient.
the two divisions of the efferent side of the peripheral nervous system are...
somatic motor neurons and autonomic neurons.
the division of the autonomic nervous system that prepares the body for intense levels of activity and stress in the
sympathetic division
the region where the axon terminal of the presynaptic cell meets the postsynaptic target cells is called the...
synapse
with the exception of olfaction, all sensory pathways first travel to the _________, which acts as a relay and processing station.
thalamus
which statement regarding the resting membrane potential is incorrect?
the resting membrane potential results from activity of the sodium/potassium pump.
the blood-brain barrier is __________.
tight junctions connecting endothelial cells.
