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Psychology 210
Cellular Anatomy
Lecture 2
Cells of the Nervous System
________________
Information processing and communicating nerve cells
Glia
Addressed later
What do you know about neurons coming into this class?
How does a neuron communicate with another neuron?
What type of signal is processed in a neuron?
What are the parts of a neuron?
Parts of a Neuron
3 main parts
________________
Receive information
Soma (________________)
Cellular maintenance
________________
Transmits information
Dendrites
Tree like processes
Receives information from other neurons
Dendritic spines
Create more area for axons to transmit information
Change depending on the amount of ________________
This is one of the suggested bases for ________________ and memory
A neuron can have multiple ________________
The soma
________________- contains DNA
Nucleolus- constructs ribosomes
Endoplasmic reticulum- contains ribosomes that construct proteins
Golgi apparatus- “packages” proteins
Mitochondria- produces ________________
The Axon
Transmits information to other neurons
Myelin sheath
________________ that aids in the speed of the neural transmission
Axon terminal
End of the axon
Contains ________________________________
Also called terminal buttons
More on the Axon
Axon ________________
Where the action potential begins
Nodes of ________________
Segments of bare axon not covered by myelin
Giant Squid
Used to study axons in the 1930s-1940s
____________________________ axon visible to the eye
Doesn’t have myelin, so it is extra large to add conductance
Characterization of neurons
Sensory neurons
Translates incoming sensory information into an electrical signal
________________ Neurons
Conduct information towards the brain from the muscles and senses
Interneurons
Neurons in the spinal cord and the brain that both communicate a signal and
process that signal
________________ Neurons
Conduct information away from the brain to the muscles and senses
Motor Neurons
Translates electrical signal to the muscles and glands
Not all neurons look the same
Named by the number of extensions from the cell body
Unipolar
One extension that branches into ________________and an axon
Bipolar
Two extensions: one ________________and one dendrite
Multipolar
Many extensions: one axon, ________________dendrites
Unipolar Neurons
Found primarily in human ________________and invertebrates
Sensory neurons that conduct impulses into the brain
Bipolar Neurons
Found primarily as sensory neurons in ________________, audition and olfaction
Multipolar neurons
Found everywhere else
Brain
Peripheral autonomic nervous system
________________cord
What happens in a nerve
Neurons communicate information to other neurons
The signal itself is an electrical signal within the neuron
________________________________
From neuron to neuron, communication is ________________
The Resting Potential
Two forces at work in a neuron
Force 1: ________________________________: the idea that the concentration of a
molecule tries to remain constant throughout the medium (substance)
The Resting Potential
Ex. Smells: the garbage begins to smell in one spot, but the smell slowly expands
throughout the house
The smell gets lighter and lighter as it ________________ throughout the house
It tries to spread out as evenly as possible
Status of the main players (ions)
Sodium (Na+): more of it ________________of the neuron
Potassium (K+): more of it ________________of the neuron
Chloride (Cl-): more of it ________________of the neuron
Based on equilibrium…
What does Na+, K+, and Cl- want to do? Are they “happy” where they are?
What direction will they move if allowed?
Due to equilibrium…
Na+ wants to move ________________the neuron
K+ wants to move ________________the neuron
Cl- wants to move ________________the neuron
What about charge?
Does charge play a role in things?
According to charge, how might the ions react?
How do charges react to each other?
________________ attract
Like charges repel
One more piece to the puzzle
There are large molecules inside the neuron with ________________ charges
Now which way do the ions want to go?
Potassium:
Which way does equilibrium push?
What about the charge?
Now which way do the ions want to go?
Chloride:
Which way does equilibrium push?
What about the charge?
Now which way do the ions want to go?
Sodium:
Which way does equilibrium push?
What about the charge?
At rest
Resting potential
-70mV
Potassium ________________________________ the membrane
Sodium and Chloride ________________ cross the membrane
Stimulation
When stimulated by another neuron, some ________________________________are
opened
K+ channels close
The action potential
If the signal is strong enough, it makes it to the axon hillock
If strong enough, an ________________________________is generated
Threshold
Begins an action potential
The action potential
Depolarization: occurs when Na+ flows ________________the cell
Due to ________________ channels opening
How’s potassium feeling now?
Sodium moving inside the cell made the inside of the cell more ________________
This ________________ potassium to move outside
The action potential
K+ channels ________________at the peak and K+ flows ________________of the cell
This repolarizes the cell and even overshoots the resting potential of before
Called hyperpolarization
Then the ________________________________brings the K back inside the cell and the
Na back outside the cell
2 K for every 3 Na
Uses energy (ATP)
The action potential
The Sodium Potassium pump restores the original environment of the resting potential so
that the neuron can fire yet again
This is known as the ________________________________period
Graded Potentials
Action Potentials are referred to as “________________________________”
Either get an action potential or not
Inputs that don’t reach threshold: Graded Potentials
Can add up across synapses/inputs to reach threshold
Saltatory Conduction
________________________________is not perfect
Signal loses strength down the axon
Regeneration of the Action Potential occurs at each ________________in the myelin
At the Axon Terminal
Vesicles containing ________________________________are present
When an action potential reaches the axon terminal, Ca2+ channels open up and this
causes the fusing of the vesicles to the membrane and the release of the neurotransmitters
into the synaptic ________________
In the Synaptic Cleft
Neurotransmitters cross the membrane and bind to receptors on the receiving neuron
Depending on the neurotransmitter, it can either ________________________________
the post-synaptic neuron
Excitatory Postsynaptic Potential (EPSP)- the excitation of the receiving neuron
Inhibitory Postsynaptic Potential (IPSP)- the inhibition of the receiving neuron
Neurotransmitters
Various ________________
Can either excite the receiving neuron or inhibit it
Acetylcholine- an excitatory NT typically found in the muscles
________________- an inhibitory NT typically found elsewhere in the nervous system
How transmission occurs
Multiple synapses on each neuronal dendrite
Some can excite while others ________________
Axon potentials can be created by multiple EPSPs from multiple neurons
Called ________________ Summation
How transmission occurs
One synapse can fire repeatedly on the same dendrite within a short temporal window
(time period)
Axon potentials can be created by multiple EPSPs from a single neuron
Called __________________________ Summation
Summary: One last thing
Transmission within the neuron is electric
Via ________________________________
Transmission between neurons is chemical
Via ________________________________
Glial cells
Astrocytes- structural support and blood brain barrier
Oligodendrocytes- myelination of axons CNS
________________ cells- myelination of axons PNS
Microglia- clean up