HuPo 5

What initiates stimulation in action potentials?

/ Initiated by a graded potential

Conductance

Conductance, ease in which ions move down a membrane

Relative Refractory period

Following the absolute refractory period there is an interval in which a second action potential can be produced, but only if stimulus strength is considerably greater than usual. 15 msec, coincides with afterhypolarization

Spatial Summation

Graded potentials from different sites can infleunce the net change

Temporal Summation

Graded potentials that occur at slightly different times can influence the net change

Ganglia Location PS

PS: Close to the effector

In action potentials stimulation response depends on ligand or voltage gated channels?

Voltage Gated

Know the properties of voltage-gated Na+ , K+ and Ca2+ channels, and understand that voltage influences their gating, activation, and inactivation.

Voltage Gated Calcium channels - Arrive at axon terminal end and opens up calcium channel, which promotes vesicle fusion and neurotransmitter release.

Describe chemical neurotransmission, listing in correct temporal sequence events beginning with the arrival of a wave of depolarization at the pre-synaptic membrane and ending with a graded potential generated at the postsynaptic membrane.

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o Understand the cell properties that determine the rate of electrotonic conduction. Compare conduction velocities in a compound nerve, identifying how the diameter and myelination lead to differences in conduction velocity.

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In graded pontentials does stimulation depolarize or hyperpolarize the neuron?

Can be either

Graded Potentials can the response be summed?

Can be summed

Action Potentials can the response be summed?

Cannot be summed

Action Potentials does the amplitude of the initial response vary, or is it independent of the initiating event?

Constant for a given cell type under constant conditions

Overshoot

Difference in membrane voltage between AP peak and 0 MV

Undershoot

Difference in membrane voltage between most negative AP value and original RMP

Graded Potentials does the amplitude of the initial response vary, or is it independent of the initiating event?

Duration varies with inidiating conditions

Abosolute refractory Period

During the action potential, a second stiulus no matter how strong will not reproduce a second action potential, that membrane is in the absolute refractory period. Follo

Differentiate between the properties of electrotonic conduction, conduction of an action potential, and saltatory conduction. Identify regions of a neuron where each type of electrical activity may be found.

Electrotonic is a graded potential. Action potentials are called saltatorial conductions because they look like they jump from node to node.

What initiates stimulation in graded potentials?

Environmental stimulus (receptor), neutroansmitter, spontaneously

In graded potentials Stimulation response depends on ligand or voltage gated channels?

Ligand Gated

Equilibrium potential?

Membrane voltage keeps K from moving down its gradient.

Understand how the activity of voltage-gated Na+ and K+ channels generates an action potential and the roles of those channels in each phase (depolarization, overshoot, repolarization, hyperpolarization) of the action potential.

Na activates > Depolarizes Cell > Inactivates > K+ Activates, Polarizes cell > Threshold reached Cell fires -> Two potassium channel populations causes undershoot -> Cell readies to fire again

Graded Potentials is there a refractory period or not?

No refractory period

In action potentials does stimulation depolarize or hyperpolarize the neuron?

Only depolarization

Number of Postganglionic neurons that synapse with a single preganglionic location PS

Ps: 3 or less

Preganlionic Location PS:

Ps: hindbraina nd sacral regions of the spinal chord

Action Potentials is there a refractory period or not?

Refractory Period

Number of Postganglionic neurons that synapse with a single preganglionic location S

S: 10 or more

Ganglia Location S

S: Chain that runs close to the spinal chord

Preganglionic Location S

S: Thoracic and lumbar regions of the spinal cord

Axon Hilock

Signal integration at Axon Hillock region a slight depolarization, 15 millivolts, going to fire action potentials all along axon

Understand descriptively (NO calculations required!) how the length constant of a membrane is important in the propagation of an action potential.

The higher the concentraiton of solute, the more collision, the more, length constant, resistivity, the better the signal of the cell carries because of the particles bouncing around.

What is threshhold potential?

The membrane potential at which an action potential is insitiated.

Soma

The part of a neuron containing the nucleus but not incorporating the axon and dendrites.

Contrast the mechanisms by which an action potential is propagated along both nonmyelinated and myelinated axons. Predict the consequence on action potential propagation in the early and late stages of demyelinating diseases, such as multiple sclerosis.

Two ways to increase speed: myelin and increasing the diameter of the axon Demyleniating diseases slow the speed of neuron signals

Dendrites

a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.

Axon

the long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells.

Axon Terminal

the somewhat enlarged, often club-shaped endings by which axons make synaptic contacts with other nerve cells or with effector cells contain neurotransmitters.