Ch. 11 Nervous System part 1 Flashcards

Ch. 11 Nervous System part 1

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All-or-none phenomenon

It either happens completely or not at all, must reach the thresh hold.

During depolarization, what electrical changes happen inside of the neuron?

Na channels open an influx creates the inside of the membrane to become less negative than the resting potential.

Where are the voltage-gated Na channels to propagate an action potential located on myelinated axons? What is different about this design from an unmyelinated axon?

Nodes of ranvier, makes them faster.

6 steps that occur at the synapse for information transfer.
Step 1:

Action potential arrives at axon terminal voltage gate Ca channels open.

6 steps that occur at the synapse for information transfer.
Step: 2

Vesicles bind to to presynaptic neurons membrane.

6 steps that occur at the synapse for information transfer.
Step: 3

Ca2+ entry causes neurotransmitter containing vesicles to release their contents by exocytosis.

6 steps that occur at the synapse for information transfer.
Step: 4

Neurotransmitter diffuses across the synaptic cleft and binds to specific receptors on the post synaptic membrane.

6 steps that occur at the synapse for information transfer.
Step: 5

Binding of neurotransmitter opens ion channels resulting in graded potential .

6 steps that occur at the synapse for information transfer.
Step: 6

Neurotransmitter effects are terminated.

List the differences in group A, group B, and group C fibers.

A: Mostly somatic sensory and nerve serving the skin, skeletal muscles and joints, large diameter.

B & C: Autonomic, serve visceral organs B is slightly myelinated, 15 m/s Medium sized. C are smaller & unmyelinated 1 m/s or less.

What axonal events occur during depolarization and repolarization?

Depolarization: influx of of Na+ the inside becomes more positive K+ channels close.
Repolarization: Na+ closed K+ channels open, hyper polarization occurs before resting potential is reached.

What is the absolute refractory period? How does it differ from the relative refractory period?

Absolute refractory period, periods of time are absolute (no other action potentials occur)
Relative: if it is strong another action potential can occur.

what is another name for an action potential?

nerve impulse

What are the functions of astrocytes?

Control chemical environment (Ca, K+), capillary permeability (leakiness), support neurons.

What is the sheath of a schwann cell called?

Neurilemma

Where do we find bipolar neurons?

Special sense organs

what are the general functional characteristics of neurons?

Transmits signals, does not repair, long lived, high metabolic rate.

What type of ion channel opens in response to a change in the resting membrane potential so an action potential can be generated?

Voltage gated

How does one neuron communicate with another neuron? what means does the first neuron utilize to transmit information to the second neuron?

Neurotransmitter by synapses

What is saltatory conduction and what cellular structure makes it possible?

Myeline sheath, action potential jumps from each node of ranvier

List the chemical classes of neurotransmitters

Acetylcholine, biogenic amine, peptides,amines, purines, gasses and lipids.

After depolarization has occurred and an action potential has peaked, which ion gates must open?

K+

What is an inhibitory post-synaptic potential? what is it associated with?

Hyperpolerization, influx of Ca, action potential is not generated.

Graded potentials

Short lived, localized, hyper polarization, decays quickly away from point of stimulus.

What is white matter?

Myelinated neurons

What is gray matter?

No myelination, includes cell bodies.

3 different types of neurons and their characteristics.

Bipolar-
Unipolar-
multipolar-

Schwann cells

Vital to regeneration of damaged peripheral nerve fibers.

Microglia

monitor the health of nearby neurons, migrate towards injured neurons, phagocytose invading microbes or or neuronal debris.

Ependymal

line central cavities of the brain and the spinal cord, where they form a permeable barrier between the CSF and the tissue fluid. circulate CSF with cilia