A&P chapter 12
____ are membrane molecules that use the energy of ATP to move ions against a concentration gradient
pumps
during ______ ______ an axon is either incapable of generating an action potential or requires a larger than normal stimulus
refractory period
A return of the membrane potential towards the resting membrane potential immediately following depolarization is called _____.
repolarization
If several EPSPs occur at different synapses, they undergo ______ at the initial segment
spatial summation
Identify all of the components of the central nervous system
spinal cord and brain
Receptors detect changes in the external or internal environment. These changes are called
stimuli
The process by which postsynaptic potentials are added together at the initial segment is known as
summation
Axon
the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
The all or none law refers to the fact that action potentials will only occur if the initial segment reaches
threshold
In the initial segment, an action potential is generated if the membrane potential reaches the
threshold value
Dendrites transfer information ___ the cell body
toward
Which of the following are structural classifications of neurons
unipolar, bipolar, multipolar
Which two are divisions of the sensory nervous system?
visceral division, somatic division
Place the events of synaptic transmission from earliest to latest
1. Action potential reaches synaptic knob 2. Voltage gated calcium channels open 3. Calcium enters the synaptic knob 4. Calcium triggers exocytosis of vesicles 5. Neurotransmitter diffuses across synaptic cleft 6. Neurotransmitter binds to postsynaptic receptors
Place the events of an EPSP in order
1. Excitatory neurotransmitter binds to chemically gated cation channel 2.more Na+ enters postsynaptic cell that K+ leaves 3. The inside of the cell becomes more positive 4. The local current of Na+ becomes weaker as it moves towards the axon hillock
Place the events of a chloride based IPSP in order from earliest to largest
1. Inhibitory neurotransmitter binds to postsynaptic chemically gated chloride channels 2. Chloride moves from outside the cell to the inside 3. The inside of the post synaptic cell becomes more negative 4. The local chloride current becomes weaker as it moves away from the neurotransmitter binding site
The voltage gates sodium channels undergo changes in activity during the depolarization phase of an action potential.
1. The membrane potential is -70 mv 2. Sodium ions flow into the neuron 3. The membrane potential becomes more positive 4. Voltage gated sodium ion channels open 5. -55mv threshold is reached
Sensory ___ neurons carry information ____ the central nervous system
Afferent/toward
Voltage-gated sodium channels ___ during the relative refractory period
Are returning to the resting state
The ____ division of the nervous system is subdivided into the sympathetic and parasympathetic division
Autonomic
The presence of ____ ions causes the synaptic vesicles to bind to the membrane, causing neurotransmitters to be released
Calcium
axon hillock
Cone shaped region of an axon where it joins the cell body.
Which terms are used for the structural classification of nerves
Cranial and spinal
The "E" in EPSP stands for ___, meaning that the potential makes the inside of the postsynaptic cell more ___
Excitatory/positive
Match the location with the larger concentration or ions
Extracellular- chloride/sodium Intracellular-organic anions/potassium
___ describes the propagation of depolarization down an axon
Flow of Na+ to downstream regions causes depolarization of adjacent regions
Neuron cell bodied in the peripheral nervous system are found clustered in
Ganglia
A(n) ____ results in a swelling, or enlarged portion, along the length of the nerve, which is often large enough to be observed with the naked eye
Ganglion
Synapses occurs where axons contact which of the following
Gland cells, muscle cells and other neurons
____ is what underlines the absolute refractory period
Inactivation of sodium channels
The "I" in IPSP stands for ___, meaning that the potential makes the inside of the postsynaptic cell more ___
Inhibitory/ negative
If summated PSPs reach threshold, an action potential begins first in the
Initial segment
____ cells wander through the CNS and replicate in response to an infection
Microglial
____ nerves contain both sensory and motor neurons
Mixed
Derived from certain amino acids
Monoamine
As more neurotransmitter is released, ___ channels open in the postsynaptic neuron
More
A (n) _____ is much more efficient because saltatory conduction occurs and less energy is required to maintain the RMP
Myelinated axon
Which of the following jobs have leak channels on the plasma membrane
Na+, K+
________________ is the propagation of an action potential along an axon
Nerve impulse
In the ___ there are a lot of ion channels and very little myelin
Neurofibril node
Chain of amino acids secreted as neurotransmitter
Neuropeptide
A toxin which interferes with the activity of neurons is called a ____
Neurotoxin
Bipolar neurons have one axon and ___ dendrites
One
When the inactivation gate of the V-gated Na+ channel closes the activation gate is
Open
fascicle is surrounded by
Perineurium
Which of the following membrane transporters are present throughout the membrane of a neuron
Potassium leak channels, sodium leak channels and Na+/K+ pumps
The period following an action potential in which an action potential can be initiated with a larger stimulus is known as the ____ ____ period
Relative refractory
A nerve impulse that "jumps" from node to node is called ___ conduction
Saltatory
___ help regulate fluid composition including the exchange of nutrients and waste in the nervous system
Satellite cells
A ___ neuron transmits stimuli to the interneuron
Sensory
Considered types of effectors
Skeletal muscle, cardiac muscle, glands
The flow of ___ ion is the most common cause of depolarization
Sodium
____ are voltage gated ion channels that have two gates
Sodium channels
Which of the following segments of a neuron contain large numbers of voltage-gated potassium channels and voltage-gated sodium channels
The conductive segment and initial segment
What must happen in order for a chemical signal to change the membrane potential of a neuron
There must be a change in ion flow across the membrane. There must be a change in the number of open ion channels
The conductive segment of a neuron is/are the ___
Total length of the axiom
Vesicles involves in retrograde transport are moving ____ the cell body
Toward
voltage-gated calcium channels are found mostly in the ___ segment
Transmissive
If an analogy is drawn between an action potential and shooting a gun, then the initial segment is analogous to the
Trigger
In most cases, a single EPSP is not sufficient to cause a neuron to reach the threshold potential
True
___ neurons have a single, short neuron process that emerges from the cell body and branches like a T
Unipolar
___ are unique channels in that they have three states; resting, activation and inactiviation
Voltage gated channels
___ are NOT commonly found in the receptive segment of a neuron
Voltage gated ion channels
Dendrites
a neuron's bushy, branching extensions that receive messages and conduct impulses toward the cell body
Building blocks of proteins secreted as neurotransmitters
amino acids
The plasma membrane of an axon is called the ___
axolemma
The central nervous system is made of the ____ and spinal ___
brain and cord
Soma is another name for
cell body
Sensory nerves carry information ____
central nervous system
Synapses are classified as:
chemical synapses and electrical synapses
axoplasm
cytoplasm of axon
A positive change in the membrane potential is called
depolarization
The tissues that receive nerve impulses from motor neurons are called
effectors
An individual axon is wrapped in a connective tissue covering called the
endoneurium
An entire nerve is surrounded by a connective tissue covering called the:
epineurium
The nervous system is composed of the brain, spinal cord, nerves and ___
ganglia
____ occurs when the inside of a cell becomes more negative than the resting membrane potential
hyperpolarization
Glial cells are found:
in both the central and peripheral nervous system
_____ are also called association cells because they link up sensory and motor neurons.
interneurons
Which of the following are functional classes of neurons
interneurons, motor neurons, sensory neurons
________ neurons are the most common class in the CNS.
multipolar
Oligodendrocytes create the ___ sheath in the central nervous system
myelin