Nervous system
voltage-gated ion channels
A nerve impulse occurs due to ions moving through ________ in the plasma membrane.
convergence
A neuron receiving impulses from two or more different axons is experiencing _______.
bipolar neurons
A neuron that has only two projections (one axon/one dendrite) from the cell body
multipolar neuron
A neuron with a single axon and multiple dendrites; the most common type of neuron in the nervous system.
unipolar neuron
A neuron with one axon attached to its soma; the axon divides, with one branch receiving sensory information and the other sending the information into the central nervous system.
inhibitory
A neurotransmitter that causes the membrane potential to move away from threshold is considered
excitatory
A neurotransmitter that causes the opening of sodium channels is an _______ neurotransmitter
excitatory
A neurotransmitter which brings the postsynaptic membrane closer to threshold is
neuroglial cells
Also found in the nervous tissue are support cells which provide insulation and nutrients. These cells are known as the...
depolarization and repolarization
An action potential involves, in order, ______ followed by ______.
sodium channels
An action potential results from the opening of
trigger zone
An action potential will not occur unless the membrane potential at the
larger
Another factor affecting impulse conduction rate is the diameter of an axon. The _____ the diameter of an axon, the faster the impulse is conducted.
calcium
As an action potential arrives at the synaptic terminal, voltage-gated _____ channels are opened.
repolarization
As cations leave the cell, the membrane potential at that part of the membrane is reestablishing resting membrane potential. This phase of the action potential is called
Nuerilemma
As the cells wrap around the axon, cytoplasm ends up in the outermost wrapping of the cell. This layer, containing organelles and the nucleus, is called the
voltage gated potassium channels
As the peak of the action potential is reached, the sodium channels close and the _________ ___________ ___________ _________ open, allowing these ions to diffuse out of the cell.
schwann cells
Axons of the peripheral nervous system are associated with neuroglia cells called
faster
Axons that are myelinated conduct impulses at a rate _______ than unmyelinated axons.
myelinated
Axons with myelin sheaths are called
white matter
Bundles of myelinated axons form nervous system tissue called
homeostasis
By initiating responses to these changes in the body, the nervous system works to maintain
sensory neurons
Carry impulses from receptors to CNS
motor neurons
Carry impulses from the CNS to effectors
ventricles
Cells called ependymal cells line the spaces of the CNS, called _______ , and form a membrane that covers the choroid plexuses.
ependymal cells
Covers the choroid plexus; lines space in the brain (ventricles)
effectors
Decisions about responses (subconscious or conscious) are then made. This information is conveyed to
sensory function
Detects stimulus/informs CNS =
repolarization
During an action potential, opening of potassium channels results in _____ of the cell membrane.
depolarization
Entry of sodium causes _____ of the cell membrane at the location of the sodium channel.
facilitation
Finally, a neuron may receive a subthreshold signal from one neuron and make it easier for other neurons in the pool to cause excitation. This process is called
sodium-potassium pump
Following an action potential, activity of the ______ reestablishes the sodium and potassium ion distribution across the cell membrane.
threshold
For an action potential to be generated in response to a stimulus, the membrane potential must reach a level called ______, typically -55 mV
Oligodendrocytes
Form myelin in CNS
Astrocytes
Found between neurons and blood vessels (blood-brain barrier); regulate ion concentration in nervous tissue
Nodes of Ranvier
Gaps between neighboring segments of the myelin sheath are called ______ ____ ________. At these points, the axon is not insulated.
depolarized
If the membrane potential becomes less negative than the resting membrane potential, the membrane is
hyperpolarized
If the membrane potential becomes more negative than the resting membrane potential, the membrane is
myelinated; nodes of ranvier
In ________ axons, only the axon membrane exposed at the ________ ______ ________ undergo depolarization.
negative
In a resting neuron, the area just inside of the cell membrane is more _____ than the area just outside of the cell membrane.
sensory receptors
Information about our internal and external environment is detected by structures called _________ ___________, which then convert the information into impulses.
multipolar neuron
Most of the brain/spinal cord & is mylinated
oligodendrocytes in the CNS and Schwann cells in the PNS.
Myelin is formed by two cell types: _________ in the CNS and ______ _________ in the PNS.
acetylcholine
Name the neurotransmitter released from the synaptic vesicles.
nerves
Nerve impulses then travel to the central nervous system (CNS) along ___
neurons
Nervous tissue cells are specialized for receiving and sending information. The cells responsible for transmitting the information are called
neuronal pools
Neurons are organized into ______ _______, which make multiple synaptic connections, receiving and transmitting information within the brain.
Neurotransmitters
Neurons communicate chemically with each other by using ______________ at a synapse.
effector
PATELLAR REFLEX Finally, the ________ responds to stimulation by the neuron, resulting in the behavioral action of the reflex
motor neuron
PATELLAR REFLEX The ______ _______ then conducts the impulse away from the brain or spinal cord.
receptor
PATELLAR REFLEX The_________ is sensitive to a specific type of internal or external change, a stimulus.
CNS
PATELLAR REFLEX Then, the _____ ________ __________serves as a processing center for the information.
sensory neuron
PATELLAR REFLEX the _____ _________conducts an impulse about the stimulus towards the brain or spinal cord.
microglial
Phagocytes; supportive function
interneurons
Relay impulses between neurons in CNS
a value closer to 0mV
Sodium entry into the postsynaptic cell moves the membrane potential from resting (-70mV) to:
outside; inside
Sodium ions are found in a higher concentration _______ the cell, while potassium is more abundant _______ the cell.
postsynaptic neuron
The binding of the neurotransmitter to the _________ ________ causes electrical changes in the membrane.
polarized
The cell membrane of a resting neuron is described as being
anions
The cytoplasm contains many ____ such as phosphate, sulfate, and proteins. These contribute to the negative charge within the cell.
positive
The entry of sodium through the sodium channels causes the membrane potential to become more:
negative
The interior of the cell membrane is more _____ than the outside of the cell membrane.
potassium; sodium
The membrane has more channels for _____ than it has for _____
Hyperpolarization
The membrane potential actually dips lower than -70mV because the potassium channels do not close quickly enough. This phase is called
skeletal muscle
The motor division is divided further into a somatic motor division serving ________ _________
smooth muscle, cardiac muscle, and glands.
The motor division is divided further into a(n) autonomic motor division serving ____ ________
CNS to peripheral organs
The motor division transmits impulses from the
effectors
The muscles and glands whose activities are controlled by nervous activity are classified as:
impulses
The nervous system sends information via a network of cells using electrical signals called
changes
The nervous system, with its sensory receptors, detects ________ in the internal and external environment of the body.
synaptic vesicles
The neurotransmitter molecules were released from:
sensory
The peripheral nervous system is further subdivided into an afferent
diameter
The rate of impulse conduction on an axon is dependent upon myelination and _______ of the axon.
presynaptic neuron
The release of neurotransmitters by the _________ _______ is triggered by nerve impulses.
potassium
The resting cell membrane is more permeable to which ion?
peripheral organs to the CNS
The sensory division transmits impulses from the
3;2
The sodium-potassium pump actively transports _ sodium ions out of the cell for every _ potassium ions transported into the cell.
sodium out of the cell and potassium into the cell
The sodium-potassium pump moves:
nervous tissue
The tissue type called _________ ________ allows you to sense and respond to the world you live in.
threshold
The video ends by saying that an action potential will be produced if the membrane potential reaches _______.
organs
There are four types of tissues that combine to form all the ______ in the human body.
faster
Therefore, a large myelinated axon will conduct impulses ______ than a thin, unmyelinated axon.
myelin sheath
These cells, wrapped repeatedly around the axon, form a coating called a
impulse
This cycle continues, resulting in action potentials traveling down the axon. This is also called ______ conduction.
adjacent membrane
This local current stimulates the _______ ________ to reach its threshold.
grey matter
Unmyelinated axons, dendrites, neuron cell bodies, and synapses are found within nervous system tissue called
Endoneurium
What connective tissue layer surrounds an axon?
when their ligand acetylcholine binds
When do ligand-gated sodium channels open?
out of the cell
When potassium channels open, potassium flows
action potential
When the membrane potential reaches threshold, voltage-gated channels open, triggering a(n) ________ ___________ at the location.
voltage-gated sodium channels; sodium
When threshold is reached, ___________ ________ __________ __________ of the initial segment open briefly, allowing ______ to diffuse into the cell.
integrated
Within the CNS, they are ________ , creating sensations, memories, and emotional reactions.
divergence
allows an impulse originating from a single neuron to be sent to several regions within the CNS.
neurons
cells are specialized to send and receive nerve impulses.
Neuroglia
cells have a support function, though they may also send and receive impulses.
sensory neurons
conduct impulses from receptors in the PNS to parts of the brain or spinal cord
Integrative function
decides response =
unipolar neuron
found in ganglia outside the brain or spinal cord
unmyelinated
in ________________ axons, an impulse is conducted over the entire surface of the axon membrane.
bipolar neurons
in specialized parts of eyes, nose, and ears
CNS
includes the brain and spinal cord
unmyelinated
lacking a myelin sheath
convergence
makes it possible for impulses to have an additive effect or to collect a variety of sensory information.
cell membrane
myelin sheath consists of multiple layers of the _____ __________ of the neuroglia cells.
motor neuron
neurons that carry outgoing information from the brain and spinal cord to the muscles and glands
potassium ions want to diffuse from inside to outside of
potassium ions want to diffuse from...
Interneurons
relays information between neurons in the spinal cord and brain
motor function
response =
sodium ions want to diffuse from outside into the cell
sodium ions want to diffuse from ....
motor
subdivided into an efferent division
sodium channels
the first channels to open are:
PNS
which includes cranial nerves, spinal nerves, and ganglia.
inhibitory
while one that causes the opening of potassium channels is an _______ neurotransmitter.
depolarization
with the membrane potential increasing to a peak of approximately +30mV.
