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Nervous System

- Controls peripheral effectors
- Senses the internal and external environment
- Coordinate voluntary/involuntary activities
- Integrates sensory information

Somatic Nervous System

System that controls the skeletal muscles.

Heart Muscle Cells, Smooth Muscle Cells, Glandular Cells, and Skeletal Muscle Cells.

The efferent division of the peripheral nervous system innervates which four cells?

Synaptic Vesicles

Where are neurotransmitters that are ready for release stored?

Synapse

The site of intercellular communication between a neuron and another cell is the...

Oligodendrocytes

The myelin sheath that covers many CNS axons is formed by...

Schwann Cells

The myelin sheath of axons in the peripheral nervous system is formed by...

Neuron's Resting Potential

- Chemical and electrical forces both favor sodium ions entering the cell.
- Potassium ions are repulsed by positive charges outside the cell.
- Potassium ions are attracted to the negative charges inside the cell.
- Chemical forces tend to drive potassium ions out of cell.

Leakage Channels

Ion channels that are constantly permeable and are found everywhere on the axolemma.

Hypopolarization

A stimulus that opens gated sodium channels in the axon membrane.

Sodium and
Depolarize

If the permeability of a resting axon to sodium ion increases, inward movement of ___________ increases and membrane will _____________.

Neuron Resting Potential

- Membrane permeability for potassium ions greater than sodium ions
- Diffusion of potassium ions out of cell
- Interior of plasma membrane has excess of negative charges.
- Diffusion of sodium ions into cell

Sodium-Potassium Pump

- Membrane slowly loses capacity to generate action potentials.
- Intracellular concentration of Na increases
- Neuron will slowly depolarize
- Inside of membrane will have a resting potential that is more positive than normal.
These cause a failed function of the...

Negative

If potassium permeability of resting neuron increases above resting permeability, what effect will this have on the transmembrane potential? Inside becomes more....

Ion Movement Across Plasma Membrane

- ATP dependent ion pumps (Na/K pump)
- Passive or leak channels
- Voltage-gated channels (action potential)
- Chemically-gated channels (neuromuscular transmission)

Chemically-Regulated Potassium Channel

If neurotransmitter acetylcholine (ACh) causes inhibition of postsynaptic neuron- what type of membrane channel did ACh bind?

Inhibitory Stimulus

A stimulus that changes a postsynaptic neuron's membrane from resting potential to -85 mV is an....

Stronger Stimulus

If the axolemma were to become more permeable to potassium ions at rest, then what would be required to cause an action potential?

Action Potential Generation

1. Graded depolarization brings an area of excitable membrane to threshold.
2. Sodium channel activation occurs.
3. Sodium ions enter cell and depolarizes.
4. Sodium channels are inactivated.
5. Voltage-gated K channels open & K moves out of cell, initiating repolarization.
6. Na channels regain normal properties.
7. Temporary hyperpolarization occurs.

Action Potential

- During depolarization phase, membrane potential becomes positive.
- After-hyperpolarization phase, membrane potential reaches K equilibrium potential.
- During repolarization phase, Na channels close and K channels open.
- Repolarization occurs as K ions leave axon

Continue Indefinitely

How would the absolute refractory period be affected if voltage-regulated sodium channels failed to inactivate by closing their inactivation gates? It would...

Repolarization of a Neuron

During this time potassium ions move out of the cell.

Graded Potentials

If a chemical prevented the opening of voltage-regulated Na+ channels, it would affect the function of a neuron because the neuron would only be capable of producing...

Action Potential Threshold

It is more positive than the resting potential.

Action Potentials

Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons? The axon would be unable to generate....

10-um Diameter

Greatest rate of impulse conduction is a myelinated fiber of...

Saltatory Propagation

Among myelinated neurons the rapid impulse conduction from "node" to "node" is called...

Postsynaptic Neuron

A neuron that receives neurotransmitter from another neuron.

Calcium

The ion that triggers the vesicular transport exocytosis of acetylcholine into the synaptic cleft is...

Acetylcholine and Nicotinic

Cholinergic synapses release the neurotransmitter _______ which bind to _______.

Transmission at a Cholinergic Synapse

1. Action potential depolarizes synaptic terminal at presynaptic membrane.
2. Calcium ions enter synaptic terminal.
3. ACh releases from storage vesicles by exocytosis.
4. ACh binds to postsynaptic membrane receptors.
5. Chemically-gated Na channels on postsynaptic membrane activate.
6. Calcium ions are removed from cytoplasm of synaptic terminal.
7. Acetylcholinesterase hydrolyzes ACh
8. Synaptic terminal reabsorbs choline.

Synaptic Transmission

If chemically-gated sodium channels in postsynaptic membrane were completely blocked, then the _________ ________ would fail.

Neurotransmitter and
Postsynaptic

The Quantity of Neurotransmitters Released, Nature of Neurotransmitter, Frequency of Neurotransmitter Release, and Characteristics of Receptors, depend on the _________ effect on __________ membrane.

Stimulation of Cholinergic Receptors

Sodium ions enter the postsynaptic neuron by the...

EPSP

If the axon terminal of a motor neuron suddenly became permeable to calcium ions, then the motor end plate will develop...

Norepinephrine

Adrenergic synapses release this neurotransmitters...

Drug Effect on Synaptic Function

- Interferes with neurotransmitter synthesis
- Interferes with neurotransmitter reuptake
- Blocks neurotransmitter binding to receptors
- Prevents neurotransmitter inactivation.

Reabsorbs Choline

After acetylcholinesterase acts, the synaptic terminal...

EPSP

What happens to a postsynaptic neuron when chemically-regulated sodium channels are open and sodium is diffusing into the cell?

Presynaptic Facilitation by Serotonin

Calcium channels in presynaptic membrane remaining opened longer causes...

Temporal Summation

When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs?

Spatial Summation

Summation that results from the cumulative effect of multiple synapses at multiple places on the neuron is designated....

ARP

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the...

Acetylcholine

An excitatory neurotransmitter secreted by somatic motor neurons innervating skeletal muscle is...

Neurotransmitter

The substance released at axonal endings to propagate a nervous impulse is called a ....

Hyperpolarization

An inhibitory postsynaptic potential (IPSP) is associated with....

Dendrite

In classic neurobiology, the part of the neuron which normally receives stimuli is called a ....

Negatively and
Sodium

In what way does the interior surface of a cell membrane of a resting (non conduction) neuron differ from the external environment? The interior is _______charged and contains less ________.

Graded Potentials

- AKA postsynaptic potentials
- Can form on receptor endings
- Short-lived
- Brief events occurring locally on discreet portions of membrane.

False

True or False:
The all-or-none phenomenon as applied to nerve conduction states that the whole nerve must be stimulated for conduction to take place.

True

True or False:
During depolarization, the inside of the neuron's membrane becomes less negative.

False

True or False:
Strong stimuli causes the amplitude of action potentials generated to increase.

False

True or False:
Action potentials can be generated by virtually all cells of the body because all cells possess cell membranes.

True

True or False:
A graded potential that is the result of a neurotransmitter released into the synapse between two neurons is called a postsynaptic potential.

True

True or False:
Large-diamete nerve fibers conduct impulses much faster than small-diameter fibers.

True

True or False:
In myelinated axons the voltage-gated sodium channels are concentrated at the nodes of Ranvier.

True

True or False:
A stimulus traveling toward a synapse appears to open calcium channels at the presynaptic end, which in turn promote fusion of synaptic vesicles to the axonal membrane.

False

True or False:
Temporal summation occurs when the postsynaptic neuron is being stimulated by a large number of terminals from the same or different neurons at the same time.

True

True or False:
Voltage is always measured between two points (Ex. inside the cell membrane vs. outside the cell membrane) and may be called the potential between these two points.

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