Final 5
multipolar neuron
-most common type of neuron -have many dendrites and a single axon
What is the correct order for the events of neurotransmitter release from the synaptic terminal? 1 - Extracellular Ca2+ enters terminal and binds to sensor protein in the cytoplasm 2 - Exocytosis of neurotransmitter into synaptic cleft 3 - Action potential reaches axon terminal 4 - Ca2+-protein complex stimulates fusion of the docked synaptic vesicle with the plasma membrane 5 - Voltage-gated Ca2+ channels open
3, 5, 1, 4, 2
Resting membrane potential is created as a result of a greater net flow of positive charges from the ______.
ICF to the ECF
Fifty presynaptic neurons all briefly release a single burst of excitatory neurotransmitter, generating excitatory postsynaptic potentials (EPSPs) in a postsynaptic neuron. Using this example, select all that apply.
These EPSPs will be summed at the axon hillock.
The afferent or sensory division transmits impulses __________.
from peripheral organs to the CNS.
Action potentials arriving at the presynaptic terminal cause ______-gated calcium channels to open. Calcium ions diffuse into the cell and cause synaptic vesicles to release ________. Neurotransmitters diffuse from the _______ terminal across the synaptic cleft. Neurotransmitters combine with their receptor sites and cause ________-gated ion channels to open. The diffusion of _______ into the cell or out of the cell causes a change in membrane potential.
voltage, neurotransmitters, presynaptic, ligand, ions
temporal summation
- a single presynaptic neuron releases neurotransmitter' -the same location of neuron is exposed to neurotransmitter in a very short period of time
Structures and events in axon of neuron
-Area associated with saltatory conduction -site of action potential propagation -structure might be ~1 meter long
properties of local potentials
-EPSPs -cause summation -decremental -reversible -IPSPs
Select all that are true regarding the resting membrane potential.
-It has a negative value. -It is measured in millivolts. -It can range from −40 to −90 millivolts.
Select all of the following that would increase the magnitude of a postsynaptic potential.
-More neurotransmitter released from the presynaptic neuron. -More chemically gated channels open in the postsynaptic neuron.
characteristics of myelinated axons
-Myelinated axons have faster nerve impulse conduction than unmyelinated axons. -In myelinated axons, the nerve impulses "jump" from node to node, and do not have to travel the entire length of the axon membrane -Myelinated axons use less energy than unmyelinated axons.
Select all the characteristics of graded potentials.
-They are the result of chemically gated ion channels opening. -The current generated is localized. -The current generated decreases with distance.
Unipolar neuron
-have central and peripheral processes
Bipolar neuron
-have one axon and one dendrite
structures and events in cell body/dendrites of neuron
-location of EPSPS and IPSPs -site of action potential origin -site of graded (local) potentials
Astrocytes
-most abundant CNS glial cells -involved with neurogenesis, scar formation, and BBB maintenance
Anaxonic neuron
-no axons are present -only produce local potential
Structures and events at a synapse in neuron
-presynaptic membrane -contains secretory vesicles containing ACh
properties of action potentials
-require threshold -important for transmission over long distances
Select all the appropriate classifications for a nerve that sends sensory information from the eye to the brain.
-sensory, cranial
The fundamental physiological properties that enable nerve cells to communicate with other cells are
-the ability to respond to environmental changes. -the ability to produce electrical signals that are quickly conducted to other cells at distant locations. -the ability to secrete a chemical that will stimulate the next cell when an electrical signal reaches the end of an axon.
spatial summation
-various locations of receptive segment are exposed to neurotransmitter -multiple presynaptic neurons releasing neurotransmitter -can generate an EPSP, IPSP, or both
Place the items in the correct order for an IPSP from beginning to end. Not all items will be used.
1. An inhibitory neurotransmitter binds to chemically gated K+ channels 2. K+ channels open 3. K+ flows out of the neuron 4. the inside of the neuron becomes more negative 5. IPSP propagates toward the axon hillock
Events that occur when action potential reaches the transmissive segment
1. action potential reaches synaptic knob 2. voltage-gated calcium channels open 3. calcium enters the synaptic knob 4. synaptic vesicles merge with synaptic knob plasma membrane 5. neurotransmitter is released by exocytosis 6. neurotransmitter crosses synaptic cleft 7. neurotransmitter attached to receptors on a muscle, neuron, or gland cell
place the items for an EPSP in the correct order from beginning to end
1. excitatory neurotransmitter released from presynaptic neuron 2. neurotransmitter binds to chemically gated sodium channels 3. sodium channels open 4. sodium flows into neuron 5. inside of neuron becomes more positive 6. this EPSP propagates toward axon hillock
what are the classes of neurotransmitters?
ACh, amino acids, monoamines and neuropeptides are all classes of neurotransmitters.
structures that establish and maintain RMP in neurons.
Na+/K+ pump, Na+ leak channels, K+ leak channels, more sodium than chloride, more potassium and phosphate and protein
Satellite Cells
PNS cells that surround and insulate the somas
action potential graph
Phase 1 (stimulus to threshold): potential across the membrane becomes less negative Phase 2: At threshold (-55mV), voltage gated Na+ channels open quickly Phase 3: Repolarization- voltage gated potassium channels open Phase 4: hyperpolarization Phase 5: resting membrane potential, -70mV
The time when there is complete insensitivity of the plasma membrane to another stimulus.
absolute refractory period
There are approximately 100 known neurotransmitters, which can be classified into major groups:• In a class of its own is _______, as it is significantly different in structure compared to other groups. • Amino acids are the building blocks of _______ and some also serve as neurotransmitters. Examples include glutamate, _______, and aspartate. • Biogenic amines are derived from certain ______ by the removal of a(n) ______ group and the addition of another functional group. The functional group added determines whether the molecule belongs to the more specific subgroup called _______ (norepinephrine, epinephrine, and _______). • Chains of amino acids that range in length from 2 to 40 amino acids are _______.
acetylcholine, proteins, glycine, amino acids, carboxyl, catecholamines, dopamine, neuropeptides
Neurons are classified functionally according to the direction the _______ travels relative to the _____. Afferent neurons are the neurons of the sensory nervous system. They are responsible for conducting _______ input from both somatic sensory and visceral sensory receptors. Most sensory neurons are _______. Efferent neurons are the neurons of the motor nervous system, conducting ______ output from the CNS to the effectors. All motor neurons are ________. Interneurons (or ________ neurons) lie entirely within the CNS. They receive stimulation from many other neurons and carry out the integrative function of the nervous system.The most numerous types of neurons are _______.
action potential, CNS, sensory, unipolar, motor, multipolar, association, interneurons
Pain receptors in the skin send signals to the CNS for processing. These pain receptors are an example of ____________ neurons.
afferent
In order to maintain the electrochemical gradients for sodium and potassium, ATPase pumps move these ions ______ their respective gradients.
against
Pumps move substances ________ a concentration gradient, a process that requires energy. Channels instead provide the means to move a substance _____ a concentration gradient. Neurons contain the following major types of channels: • Channels that are always open, allowing continuous diffusion of a specific ion from a region of _____ concentration to a region of _____ concentration are leak channels. • Channels that are normally closed that open in response to the binding of a ________ are chemically gated channels. When open, they allow a specific ion to ______ across the plasma membrane. • Channels that are normally closed, but open in response to changes in _________ across the plasma membrane are voltage gated channels. When open, they allow a specific ion to diffuse across the membrane.
against, with, high, low, neurotransmitter, diffuse, electrical charge
The motor division is separated further into a somatic motor division and a(n) _________ motor division.
autonomic
PNS axons are vulnerable to cuts, crushing injuries, and other types of trauma. However, a damaged _____ can regenerate if the ______ remains intact and a critical amount of _______ remains. The success of PNS axon regeneration depends upon two primary factors: (1) the amount of _____, and (2) the ______ between the site of the damaged axon and the ________. The possibility of repair is _______ with an increase in either of these two factors. Neurolemmocytes play an active role in regeneration.
axon, cell body, neurilemma, damage, distance, effector organ, decreased
common features of most neurons.
axon, dendrite, soma
Acetylcholinesterase
catalyzes hydrolysis of ACh to remove it from the synaptic cleft.
When a neurotransmitter binds a protein channel, it opens and lets sodium diffuse down its concentration gradient. This is an example of a
chemically gated sodium channel.
The nervous system serves as the body's primary ________ and control system. It provides a rapid means of _______ and regulating body functions through electrical activity transmitted along specialized nervous system cells called _______ to accomplish the following: • Collect information. Specialized nervous system structures called _______ monitor changes in both the internal and external environment called ______. • Process and evaluate information. After processing ______ input, the brain and spinal cord determine what response, if any, is required. • Initiate response to information. The brain and spinal cord initiate a response as ______ output via nerves to _______. These structures include all three types of muscle tissue and glands.
communication, integrating, neurons, receptors, stimuli, sensory, motor, effectors.
types of neuronal pools
converging circuit, diverging circuit, reverbrating circuit, parallel-after-discharge circuit
Neurons that carry signals from the CNS to skeletal muscle for contraction would be classified as _____________ neurons.
efferent
The diffusional movement of sodium and potassium across the membrane is driven at all times by the ________.
electrochemical gradient.
components of a peripheral nerve in sequence from outside to inside.
epineurium, nerve, perineurium, fascicles, endoneurium, neurolemmocytes, axolemma
Neurolemmocytes
form the myelin sheath in PNS
Oligodendrocytes
form the myelin sheath in the CNS
The efferent or motor division transmits impulses ____________.
from the CNS out to the peripheral organs
Ependymal Cells
function in the production and circulation of CSF
EPSP and IPSP _______ potentials are local currents of ions that move along the plasma membrane toward the initial segment area of the ______. Graded _______ potentials are added together in the initial segment; this process is called ______. The initial segment, by adding postsynaptic potentials, determines if a(n) _________ potential is reached.This potential is ______ mV. This is a change of_____ mV from the RMP. When this threshold is reached, it initiates the opening of _______ channels and the generation of a(n)_______ potential that will travel along the axon.
graded, axon hillock, postsynaptic, summation, threshold membrane, -55, +15 , voltage-gated, action
When chloride enters the neuron via chemically gated chloride channels, the membrane potential will become more negative than the resting membrane potential. This is called _____________.
hyperpolarization
If neurotransmitter from Neuron A causes Neuron B to hyperpolarize, this is an example of an
inhibitory postsynaptic potential.
Microglia
macrophages of the CNS
The vagus nerve contains afferent and efferent neurons, therefore it is an example of a(n) __________ nerve.
mixed
When Na⁺ diffuses into the cell, the cell becomes ____ depolarized. Na+ diffusing into the cell causes more Na+ gates to open, which is a ____ feedback loop. When K⁺ diffuses out of the cell, the cell becomes ____ depolarized. K⁺ diffusing out of the cell has a _____ feedback effect on the initial polarization. The voltage-gated Na⁺ channels ______when the cell membrane reaches threshold level as a result of a stimulus. The voltage-gated Na⁺ channels ______ when the cell reaches +30mV.
more, positive, less, negative, open , close.
The peripheral nervous system is further subdivided into an afferent (sensory) division and an efferent (_____) division.
motor
structural classifications of neurons
multipolar, bipolar, unipolar, anaxonic
know the components of typical neuron
nucleolus, dendrite, axon hillock, telodendria, synaptic knobs
When sodium enters the neuron via chemically gated sodium channels, the membrane will depolarize. Therefore, the membrane potential will become more
positive
Though potassium and sodium both leak through the membrane at rest, there is a greater diffusional flow of ______ at rest.
potassium
A time when there is a decrease in the sensitivity of the plasma membrane to further stimulation.
refractory period
The time when a stronger-than-threshold stimulus is needed to initiate another action potential
relative refractory period
The relative difference in charge across a plasma membrane is the ________ in an inactive excitable cell. A _______ is used to measure the voltage difference across the plasma membrane. This is done by placing one microelectrode into the ______ and the other microelectrode outside the neuron into the ________. The RMP has a value, which is typically ____ millivolts. More positive ions reside _______ a neuron than ________ a neuron when it is at rest.
resting membrane potential, voltmeter, neuron, interstitial fluid, -70, outside, inside
Another term for the __________ system is the afferent nervous system.
sensory
Autonomic refers to the controls we are not aware of, like________ muscle, cardiac muscles, and glands.
smooth
The electrical and chemical gradients for _____ are both high during resting membrane potential which results in a very high electrochemical gradient toward the inside of the cell.
sodium
A typical synapse in the CNS consists of a presynaptic neuron and a postsynaptic neuron, separated by a narrow space called the
synaptic cleft.
When threshold is reached, depolarization occurs with the same amplitude of potential change. This is known as
the All-or-None principle.
The negative value of the resting membrane potential means
there are more negatively charged particles on the inside of the membrane than on the outside.
