Nervous System

List methods for clearing neurotransmitters from a synapse?

- They can be taken up into the presynaptic terminal. -They can be enzymatically degraded. -They are "recycled" by the presynaptic terminal. Neurotransmitters are NOT taken up by the postsynaptic neuron.

List three effects of psychoactive drugs and neurotransmitters.

1. A psychoactive drug may increase the number of neurotransmitter molecules available and thus increase the reaction. 2. A psychoactive drug may decrease the number of neurotransmitter molecules and thus decrease the response. 3. A psychoactive drug may bind to the receptor and affect the activity of the receiving neuron.

Synaptic response to an action potential

1. An action potential arrives at the synaptic terminal. 2. Calcium channels open, and calcium ions enter the synaptic terminal. 3. Vesicles containing neurotransmitter fuse with the plasma membrane of the sending neuron. 4. Neurotransmitter molecules diffuse across the synaptic cleft. 5. The neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron causing ion channels there to open.

Describe relationship between Alzheimer's and proteins.

1. The three-dimensional shape of a protein is critical for the functioning of that protein. 2. There is a link between improperly folded proteins and disease in both mad cow disease and Alzheimer's disease. 3. High heat and a change in pH can denature a protein.

Describe Alzheimer's disease.

Alzheimer's is a neurological disease with loss of memory and motor skills.

A nerve impulse moves away from a neuron's cell body along _____.

Axons conduct a nerve impulse away from the cell body.

True or False. Dependence is a progressive decrease in the effectiveness of a drug in a given person.

False.

True or False. The branch of the nervous system that regulates body functions during emergency situations is the parasympathetic nervous system.

False.

An impulse relayed along a myelinated axon "jumps" from _____ to _____.

In myelinated neurons the impulse jumps from node of Ranvier to node of Ranvier.

Axons insulated by a(n) _____ are able to conduct impulses faster that those not so insulated.

Myelin sheaths, formed when Schwann cells wrap around an axon, allow such neurons to conduct impulses more rapidly than unmyelinated axons.

Describe the movement of neurotransmitters.

Neurotransmitters are released by one neuron, diffuse across a gap, and bind to a receptor on another cell membrane, thus triggering a change in the activity of the receptor cell.

Describe the neurotransmitters norepinephrine and acetylcholine.

Norepinephrine is the neurotransmitter of the sympathetic nervous system, and acetylcholine is the neurotransmitter of the parasympathetic nervous system. In general, the neurotransmitter of the sympathetic nervous system is norepinephrine, and the neurotransmitter of the parasympathetic nervous system is acetylcholine.

Do psychoactive drugs increase or decrease the response of the receptor?

Psychoactive drugs may either increase or decrease the response of the receptor.

What type of cell makes up the myelin sheath of a motor neuron?

Schwann cells. Myelin sheaths are formed when Schwann cells wrap around the axons of motor neurons.

Which of the following events is the first to occur during an action potential?

Sodium channels open at the start of an action potential.

Describe the interaction of sympathetic and parasympathetic nerve fibers.

Sympathetic and parasympathetic nerve fibers may innervate the same organs, but they have generally opposite effects. Sympathetic and parasympathetic nerve fibers usually have antagonistic effects on the same organ.

What part of a neuron relays signals from one neuron to another neuron or to an effector?

Synaptic terminals contain neurotransmitter molecules that relay the nerve impulse across a synapse.

What causes an action potential to be conducted along a neuron's axon?

The change in charge difference across the membrane spreads from open sodium channels, causing sodium channels farther along the axon to open, starting an action potential farther along the axon.

A certain drug prevents a neurotransmitter from initiating a response in the receiving neuron. Describe the mechanism by which the drug may be acting.

The drug is preventing the neurotransmitter from binding to its receptors in the receiving neuron. If the neurotransmitter cannot bind to its receptors in the receiving neuron, it would not be able to initiate a response in that neuron.

Describe the sequence for the electrical transmission of a nerve impulse.

The impulse comes from the presynaptic neuron, crosses the synapse, and stimulates the postsynaptic neuron.

During an action potential the inside of the neuron ______

The inside of a neuron becomes positively charged relative to the outside during an action potential.

What is the cause of multiple sclerosis?

The myelin sheaths in the brain and spinal cord are destroyed.

When the neurotransmitter crosses the synapse, what happens?

The neurotransmitters bind to the postsynaptic ion channels, causing them to open. If the synapse is excitatory, the postsynaptic membrane will depolarize.

When discussing the origins of the sympathetic and parasympathetic divisions of the autonomic nervous system, parasympathetic nerves ____, and sympathetic nerves ____.

The parasympathetic nerves arise from the brain and part of the spinal cord, and all of the sympathetic nerves arise from the spinal cord. Nerves of the parasympathetic division emerge from the brain stem (cranial nerves) and the sacral segment of the spinal cord; all of the sympathetic nerves emerge from the thoracic and lumbar spinal cord.

Describe the relative physical position of the ganglia of the sympathetic and parasympathetic nervous systems.

The sympathetic ganglia are located in chain-like fashion near the spinal cord. The parasympathetic ganglia are located closer to their target organs.

Picture yourself being chased by a herd of wild elephants. What are the sympathetic and parasympathetic actions on your heart?

The sympathetic nervous system will cause the heart rate to speed up. The parasympathetic nervous system will be "overridden." The sympathetic nervous system is active in crisis situations. The parasympathetic nervous system is overruled by the sympathetic response.

Describe a synapse.

The synapse includes the presynaptic membrane, the postsynaptic membrane, and the space between them.

When a neuron is at its resting potential there are more ____ inside than outside.

There are more potassium ions inside the neuron than outside. Sodium-potassium pumps actively transport sodium ions out of the cell and potassium ions into the cell. The result is that the neuron has more potassium ions and fewer sodium ions inside the cell.

Amphetamines are drugs that can bind to the same receptors as the neurotransmitter norepinephrine and can also inhibit the enzymes that break down norepinephrine. Describe the effects amphetamines would most likely have on norepinephrine action?

They produce the same effects as norepinephrine for a prolonged period of time. Amphetamines mimic the effects of norepinephrine, so they produce similar effects in the receiving neuron as the neurotransmitter. Because they prevent norepinephrine from being degraded, they also prolong its effects in the receiving neuron.

True or False. An action potential is caused by sodium and potassium crossing the cell membrane.

True.

True or False. Electrical impulses CANNOT cross the synaptic cleft between adjacent neurons without a neurotransmitter.

True.

True or False. Insufficient production and activity of the neurotransmitter serotonin are associated with depression.

True.

True or False. There is a correlation between beta-amyloid plaques and the severity of Alzheimer's disease.

True.

A neuron's nucleus is located in its _____.

cell body

What best describes how signals travel on neurons in the human body?

dendrite → cell body → axon

A nerve impulse moves toward a neuron's cell body along _____.

dendrites conduct an impulse from a synapse toward the cell body.

Neurons with a myelin sheath carry impulses __________ unmyelinated cells.

faster than

The synaptic cleft __________.

is a gap between two neurons.

Sodium-potassium pumps restore ____

restore the distribution of ions inside and outside a neuron's membrane following an action potential. Following an action potential, sodium-potassium pumps restore the distribution of ions back to their levels at resting potential.

If someone were to yell, "Fire!" now and you suddenly began to smell smoke, which part of your nervous system would become activated to prepare your internal body systems to deal with the dangerous situation?

sympathetic system