CAS BI 315 Chapter Notes - Chapter 3: Resting Potential, Nicotinic Acetylcholine Receptor, Electrical Polarity
1 Jul 2018
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Lab 3: Neurosimulation of Excitable Cells
I. Membrane potential - diff in electrical charge across the plasma membrane
II. Resting membrane potential (RMP) - around -70 mV
A. Established by conc gradients and relative permeability to ions
B. Maintain by pump and leaky k channels
III. Graded potentials and action potentials are changes in membrane potential
A. Graded can summate
B. Graded potentials can be EPSPs or IPSPs
IV. Receptor potentials - generated by sensory neurons as they transduce a stimulus into
electrical signal
V. Synaptic potentials - nt binding to receptors that directly or indirectly open ion channels
in postsynaptic membrane
VI. Depolarization - Ach bind to nicotinic receptors which are also ligand gated ion
channels that inc permeability to na and k and allow inc voltage
VII. Hyperpolarization - becomes more - than at rest (GABA- inc Cl- perm) - cl- comes in
VIII. In a graded potential, the change in potential is proportional to the intensity of the
stimulus
IX. Action potentials - result from a rapid and reversible change in electrical polarity of
plasma membrane- perm of na
A. Threshold
B. All or none - mag of change in membrane polarization during AP is constant
irrespective of stimulus intensity - intensity doesnt change AP strength
B.1. Anything above threshold outside of the relative refractory period
will have the same strength of AP
B.2. Within relative refractory period, APs will be smaller (lower voltage
of depolarization)
C. Node of ranviers: myelination of axon allows faster transmission speed bc AP
can hop to each node.
D. Absolute refractory period - time when another AP cant be generated
E. Relative refractory period - time when a 2nd AP can be generated but requires
stronger stimulus
F. Vocab:
F.1. Stimulus - detectable change in internal or external environment
F.2. Stimulus Strength: Amplitude.
F.3. Stimulus Duration: Length of Time the stim is applied.
F.3.a) Longer duration gives a higher freq of AP
F.3.b) Even a subthreshold stim can generate an AP if stim has
longer duration.
F.4. Stimulus Frequency: number of cycles per unit time\
X. A neuron changes the permeability at rest by varying the amount of protein channels
produced which affects the number of leaky K+ and Na+ channels
XI. Prelab graph: ion concentration effects on RMP
A. RMP way more affected by increasing permeability to Na than to K
B. This is bc membrane already has leaky K+ channels so RMP is already close to
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Document Summary
Lab 3: neurosimulation of excitable cells: membrane potential - diff in electrical charge across the plasma membrane. Resting membrane potential (rmp) - around -70 mv: established by conc gradients and relative permeability to ions, maintain by pump and leaky k channels. Graded potentials and action potentials are changes in membrane potential: graded can summate, graded potentials can be epsps or ipsps. Receptor potentials - generated by sensory neurons as they transduce a stimulus into electrical signal. Synaptic potentials - nt binding to receptors that directly or indirectly open ion channels in postsynaptic membrane. Depolarization - ach bind to nicotinic receptors which are also ligand gated ion channels that inc permeability to na and k and allow inc voltage. Hyperpolarization - becomes more - than at rest (gaba- inc cl- perm) - cl- comes in. In a graded potential, the change in potential is proportional to the intensity of the stimulus.
