A&P Ch 8 HW & quizzes
Binding of a neurotransmitter to its receptors opens ________ channels on the __________ membrane.
chemically gated; postsynaptic
What do ependymal cells do?
Ependymal cells line the central canal and ventricles of the brain and produce cerebrospinal fluid (CSF).
In a synapse, neurotransmitters are stored in vesicles located in the
presynaptic neuron
dendrites:
receive messages
Detect information from external environment or our physical position in the environment
Somatic sensory receptors
Receptors monitoring the internal environment
Visceral receptors
The velocity of the action potential is fastest in which of the following axons?
a small myelinated axon
axons:
send messages
Afferent nervous system
sensory information moving toward CNS
An action potential releases neurotransmitter from a neuron by opening which of the following channels?
voltage-gated Ca^2+ channels
What is the value for the resting membrane potential for most neurons?
-70 mV
Process of a stimulus reaction:
1. A stimulus arrives. 2. Voltage-gated sodium channels open. 3. Sodium enters the cell. 4. Cell is depolarized. 5. Voltage-gated sodium channels close as voltage-gated potassium channels open. 6. Potassium leaves the cell. 7. Cell is repolarized.
Conduction along a neuron that does not have myelin.
Continuous propagation
What occurs when multiple neurons feed into a single neuron?
Convergence
The membranes of neurons at rest are very permeable to ______ but only slightly permeable to ______.
K+; Na+
Neuron with two or more dendrites and a single axon.
Multipolar
Polarized state of a neuron; measuring at -70 mV
Resting membrane potential
Oligodendrocytes are to CNS as ______ are to PNS.
Schwann cells
Produce myelin in PNS
Schwann cells
Hyperpolarization results from _______.
slow closing of voltage-gated K+ channels
When a stimulus reaches and excites a neuron causing a sodium ions to move inside and changing the measurement from -70 mV towards +30 mV (depolarization).
Action potential
How is an action potential propagated along an axon?
An influx of sodium ions from the current action potential depolarizes the adjacent area.
Maintain blood-brain barrier; structural framework for CNS; repairs damaged neural tissues
Astrocytes
Neuron with continuous dendrites and axon with the cell body.
Unipolar
Peripheral nervous system
all nerve tissue outside the CNS
A given stimulus either triggers a typical action potential or it does not produce one at all.
all-or-none principle
Sympathetic nervous system
associated with fight or flight situations
Parasympathetic nervous system
associated with resting and digesting phase
Where in the neuron is an action potential initially generated?
axon hillock
Neuron with two processes-one dendrite and one axon with the cell body in between.
bipolar
Situation when the membrane potential becomes more negative than -70 mV.
hyperpolarization
The ventral root (CNS) carries _______ information ________ the spinal cord.
motor; from
cell body:
nucleus
Period of time when the neuron cannot respond normally to further stimulation.
refractory period
When the sodium gates close and the potassium gates open causing the measurement inside the cell to move from +30 mV towards -70 mV.
repolarization
What is the difference between saltatory and continuous propagation of nerve impulses?
Saltatory carries impulses at a faster rate than continuous propagation.
Conduction that occurs along a neuron with myelin.
Saltatory propagation
Found in the PNS and support neuron cell bodies
Satellite cells
Also called afferent; transmit impulses from sensory receptors to CNS
Sensory neurons
Middle meningeal layer surrounding the brain and spinal cord
arachnoid
During depolarization, which gradient(s) move(s) Na+ into the cell?
both the electrical and chemical gradients
Unlike neurons, neuroglia are
capable of cell division
Opening of voltage-gated sodium channels in the membrane of a neuron results in
depolarization
Outermost layer; outer portion fused with skull periosteum
dura mater
Binding of the neurotransmitter to its receptor causes the membrane to _______.
either depolarize or hyperpolarize
Location of gray matter (neuron cell bodies) in the PNS
ganglia
Local potential or changes in the membrane potential that cannot spread far from the site of stimulation.
graded potential
Central nervous system
includes the brain and spinal cord
Also called association neurons; located in the CNS only; interconnect sensory and motor neurons
interneurons
Autonomic nervous system
involuntary control of smooth muscles, cardiac muscle, and glands
The repolarization phase of an action potential results from ________.
the opening of voltage-gated K+ channels
Change necessary for an action potential to occur (-55 mV).
threshold
Bundles of axons (white matter) in CNS
tracts
The innermost meningeal layer firmly bound to the neural tissue (brain and spinal cord)
pia mater
Which term best matches the following description: polarized-positive on the outside and negative on the inside; measures at -70 mV.
resting membrane potential
Which of the following provides control over skeletal muscles?
somatic nervous system
The depolarization phase of an action potential results from the opening of which channels?
voltage-gated Na+ channels
Somatic Nervous system
voluntary control of skeletal muscles
What is the magnitude (amplitude) of an action potential?
100 mV
The entire spinal cord is divided into ______ segments.
31
Have cilia on one surface to help move CSF around the CNS
Ependymal
The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?
Na+ is pumped out of the cell and K+ is pumped into the cell.
Phagocytic cells that engulf cellular waste and pathogens
Microglia
Also called efferent; carry instructions from CNS to muscles and glands
Motor neurons
The concentrations of which two ions are highest outside the cell.
Na+ and Cl-
Produce myelin in CNS
Oligodendrocytes
Why does the action potential only move away from the cell body?
The areas that have had the action potential are refractory to a new action potential.
The mechanism by which the neurotransmitter is returned to a pre-synaptic neuron's axon terminal is specific for each neurotransmitter. Which of the following neurotransmitters is broken down by an enzyme before being returned?
acetylcholine
The brain and spinal cord comprise the
central nervous system
Efferent nervous system
motor commands moving from CNS to muscles/glands
Bundles of axons (white matter) in PNS
nerves
Portion of the brain where gray matter is located and is the sight for complex integration
neural cortex