KIN 155 Study Guide - Midterm Guide: Resting Potential, Sodium Channel, Stimulus Modality

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KIN 155: Mid Term Review
Neurons and the Atom
Neurons are the communicators of the nervous system
Send electrical and chemical impulses
There are 100 billion neurons within nervous system with 100 000 billion synapses
Glial cells are non-neuronal cells that maintain homeostasis, form myelin and provide
support/structure for neurons
Neuron Structure
Neurons
Afferent Neurons
Convey information
away from the brain.
Efferent Neurons
Taking information
outside of the brain
(senses)
Interneurons
Convey information
across different
neurons.
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Dendrites receive information
Cell Body - central database which contains the nucleus and other membrane bound organelles
Axon Hillock bridge between axon and cell body
Axon transmit action potential
Axon Terminal presynaptic endings which synapses to a postsynaptic membrane
Neuron to Neuron Communication
it is a form of electrochemical communication
resting membrane potential: inside of the cell is negative compared to the outside
depolarization: becoming more positive
hyperpolarization: becoming more negative
action potential: rapid depolarization and repolarization of the membrane potential
all or none response: if the stimulus reaches threshold, it will fire in an all or none fashion
Resting Membrane Potential
Steady state of membrane potential
Approximately -65 mv to -70 mv
Determined by ion concentration (and charge) inside and outside of the cell membrane
Organic anions and potassium have a bigger concentration in the inside as compared to the
outside
Na+ and Cl- have a larger concentration on the outside as compared to the inside
Remember that ions are attracted to opposite charge which will cause the diffusion of the
concentration gradient
Neuron Action Potential
The neuron starts at its resting membrane potential of -70 mv
IPSP or EPSP will make contact with the dendrite and will cause changes to the voltage (either
negative or positive)
If it reaches threshold, an action potential will launch
Sodium channels will open when it reaches threshold so sodium can go inside the membrane
and make it depolarize due to the excess positive charge
Potassium exits the neuron through leak channels and voltage gated channels which causes the
overall charge to be more negative which leads to hyperpolarization
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EPSP vs. IPSP (Neuron)
EPSP: moves the cell towards threshold by allowing positive ions to enter the cell as a result of
the opening of ligand gated ion channels. (Larger the EPSP, more likely the action potential is to
fire)
IPSP: move the cell away from threshold due to movement of negative ions into the cell or
positive ions out of the cell
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Document Summary

Neurons are the communicators of the nervous system. There are 100 billion neurons within nervous system with 100 000 billion synapses. Glial cells are non-neuronal cells that maintain homeostasis, form myelin and provide support/structure for neurons. Cell body - central database which contains the nucleus and other membrane bound organelles. Axon hillock bridge between axon and cell body. Axon terminal presynaptic endings which synapses to a postsynaptic membrane. Neuron to neuron communication it is a form of electrochemical communication resting membrane potential: inside of the cell is negative compared to the outside. Action potential: rapid depolarization and repolarization of the membrane potential. All or none response: if the stimulus reaches threshold, it will fire in an all or none fashion. Determined by ion concentration (and charge) inside and outside of the cell membrane. Organic anions and potassium have a bigger concentration in the inside as compared to the outside.

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