Equilibrium and Resting Potentials Flashcards
receive the synaptic inputs from many other neurons and comprise the major receiving portion of a neuron (they basically act like the neuron’s ears)
dendrites
conducts action potentials and thus conveys information over long distances that is onto its target neurons
axons
have specialized terminals with which they make synaptic contacts with other neurons or muscle cells
axons
Protein synthesis occurs in the
cell body of neurons
industrial region of each neuron.
cell body
refers the electrical difference between two compartments (the inside and the outside of the cell in this case) that is needed to exactly counterbalance the concentration force driving an ion from a compartment where there is a higher concentration of the ion into the compartment having a lower concentration of that ion.
The equilibrium potential
why is nervous system important
Multicellular cells are highly interdependent. The cells have become so specialized in their functions that no cell or tissue is capable of an independent existence. Hence a rapid mode of communication is important
Evolution has provided two solutions to the problem of intercellular communication:
endocrine system
nervous system
this system of communication is
accomplished by means of a chemical agent, or hormone
endocrine system
characteristic of intercellular communication via hormones is its
slowness because it is limited by the rate of blood flow
Principle Rationale for a Nervous
System
Rapid Communication Over Long Distances
system designed for rapid intercellular communication over long distances with high
fidelity
nervous system
cells that comprise the nervous system are called
neurons
In the nervous system, communication occurs by means of pulses of electrical signals called
action potential
Neurons have long cellular processes, called
axons
Neurons have long cellular processes, called axons over which
action potentials can be conducted at speeds of up to
120 meters/sec
4 major parts of neurons
cell body
dendrites
axon
axon terminal
cell body also known as
soma
soma, or cell
body, contains the
nucleus, nucleolus, endoplasmic reticulum, Golgi apparatus and all the
organelles and features that characterize all cells.
where the majority of protein
synthesis occurs, and thus is the neuron’s industrial center.
cell body
are a series of processes
that extend from the cell body, and are the parts of the neuron that receives information from
other neurons, as
dendrites
is a process that extends out from the cell body and
is the part of the neuron that conducts information from the cell body to distant sites.
axons
basically like a wire in an electrical circuit.
axons
Each neuron has how many axon/s
1
end of the axon
axon terminal
close arrangement of the axon’s terminal and the dendrite or cell body of another cell
occurs at a special site called the
synapse
The axon terminal at the synapse has numerous specializations, and the most
obvious are the
numerous synaptic vesicles
The “balloons” are actually membranous vesicles that contain a chemical called a
neurotransmitter
The major idea
is that when a signal is received at one of the dendrites, the signal triggers an electrical pulse which is an
action potential
The major idea
is that when a signal is received at one of the dendrites, the signal triggers an electrical pulse, an
action potential, at the junction where the cell body meets the axon. This particular portion of
the axon is called the
axon hillock
When the action potential reaches the axon terminal, it causes the vesicles in the terminal to
release their
chemical neurotransmitter
neurotransmitter are released into this area
synaptic cleft
When the receptors bind the chemical, they open
pores in the receptors and allow electricity, in the form of
positive ions -> flow into cell
influx of positive charges into the cell then triggers an action potential at the
axon hillock of
the receiving cell
The entire rationale of the nervous system can be condensed into a
single idea;
communication simply means that one cell influences the electrical state of
another cell by the release of chemicals at points of synaptic contact.
The communication between two cells,
where one releases neurotransmitter and the other has receptors that bind the neurotransmitter,
occurs at the
synapse
are the universal conveyors of information in all multicellular animals
action potential
Axons and action potentials have three basic and essential attributes for conducting
information. Please enumerate
- conducted over long distances
- high fidelity
- propagated rapidly
Additionally, the neurotransmitter is
released only in the
synaptic cleft
knee jerk reflex involves with what muscle
quadriceps femoris
stretch receptors in muscles are called
muscle spindles
electrical change in the sensory axon ending is called
receptor potential
If the receptor potential is sufficiently large, it will initiate a second type of electrical signal
near the afferent axon endings on the muscle spindle.
action potential
electrical change that will propagate along axon from the muscle spindle into the spinal cord
action potential
The stretched muscle also
stretches the
sensory receptors on the muscle spindle.
The stretched receptor changes the electrical state of the receptor that is called a
receptor potential
second neuron in the reflex circuit
motor neuron
The open pores allow
______ to enter the soma of the motor neuron thereby changing its electrical state
positive charges
The change
in electrical state of the motor neuron is called a
synaptic potential
The action potential propagates along the sensory axon at this speed
100-120 m/sec
separating the membranes of the sensory terminal and the
motor neuron dendrite
synaptic cleft
The increase
in positivity is confined to the region of the motor neuron near the synapse and it is graded in
proportion to the
amount of transmitter released at the synapse
the satellite cells of the nervous system
glial cells
Indeed most cells in the nervous system are called
glial cells/ glia
four
major types of glial cells in the nervous system. Please enumerate
astrocytes
oligodendrocytes
Schwann cells
microglia
have elaborate processes and are only found in the brain and spinal cord. They are
not present on peripheral nerves, such as on the axons of motoneurons or on sensory nerves. Their
major function is to maintain a normal chemical environment for neuronal signaling.
Astrocytes
are also restricted to the brain and spinal cord, and form the myelin sheaths
around some, but not all neurons
oligodendrocytes
The processes of these glial cells wrap around a portion
of and axon thereby creating the myelin sheath.
oligodendrocytes
are related to oligodendrocytes, but are only found in the peripheral nervous
system (the nerves outside of the brain and spinal cord) where they form the myelin sheaths
around peripheral neurons
Schwann cells
a type of glial cell that act like the macrophages in other tissues
Microglia
They
are primarily scavenger cells that remove cellular debris from sites of neuronal injury
Microglia
