BIO168 Ch.11

GABA

this is the main inhibitory neurotransmitter. Individuals prone to anxiety may have reduced levels.

Glutamate

this is the primary excitatory neurotransmitter and is important in memory and learning. Glutamate returned

Serotonin

this neurotransmitter increases mood (decreased levels are associated with depression), stimulates sleep and inhibits appetite.

Sensory information is collected by sensory receptors in the PNS. Input travels to the CNS, where it is integrated and a response is put into action by effectors, usually muscles or glands.

A physician's assistant named Jose begins to examine Tabitha by testing her reflexes. Which statement best describes the path of information as it travels through the nervous system?

Outside +Inside -

A resting neuron is an unstimulated neuron that is not presently generating an action potential. The resting membrane potential is the separation of the relative positive and negative charges across the membrane of a cell at rest.

hyperpolarization phase.

A series of measurements with a voltmeter show a neuron's membrane potential becoming more negative, from -70 mV to -85 mV. This neuron is experiencing a:

inability to generate action potentials

Batrachotoxin produced by certain species of frogs is a toxin that permanently opens voltage-gated Na ion channels. The results of exposure to batrachotoxin will be:

During the inactivated state the inactivation gate is closed and the activation gate is open.

Choose the figure that represents an inactivated voltage-gated Na ion channel.

The receptors will be downregulated (decreased). This will lead to desensitization of dopamine response.

Cocaine blocks the reuptake of dopamine, causing a high level of dopamine that stimulates the postsynaptic receptors for an extended period. Why would people who abuse cocaine eventually need more of the drug to reach an equivalent "high"?

large myelinated axon

Conduction speed will be fastest in a __________.

diffusion of Na ions down to the next segment of the axon

Depolarization to threshold during action potential propagation in axons is due to:

K++ efflux

During an action potential, hyperpolarization is caused by:

the repolarization phase

During an action potential, the rapid decrease in sodium ion permeability and the simultaneous and rapid increase in potassium ion permeability is responsible for __________.

The pre-synaptic neurons would be unable to release neurotransmitter.

Heavy metals can block calcium channels in neurons. Predict what would happen to Tabitha's neurons.

A drug that acts as an opioid agonist

Heroin addicts can now be given pharmaceutical treatment to help curb their desire and addiction. Which mechanism would help an addict decrease their addiction?

the neurotransmitter will have no effect in the postsynaptic cell

If a drug inhibits neurotransmitter receptors on the postsynaptic cells:

Sympathetic nervous system

Injuries may damage the nerves of any motor or sensory division of the PNS. In which PNS subdivision would a nerve injury be the most threatening to survival?

1. An action potential reaches the axon terminal 2. An influx of Ca2+ triggers the release of neurotransmitter 3. The neurotransmitter diffuses across the synaptic cleft 4. Na+ enters the postsynaptic neuron

Let's begin with an overview of the events that occur at a chemical synapse. Select the correct label and drag to the appropriate location.

increased levels of dopamine in the synaptic cleft

Nicotine is addictive because it causes dopamine-releasing neurons to fire more action potentials. Nicotine will therefore cause:

Reploarization

Potassium ions are moving out, and the membrane potential is becoming more negative as it moves back toward the resting membrane potential.

Hyperpolarization

Potassium ions are moving out, and the membrane potential is becoming more negative than the resting membrane potential.

Depolarization

Sodium ions are moving in, and the membrane potential is becoming less negative than the resting membrane potential.

Glutamate is the most important inhibitory neurotransmitter in the central nervous system.

Tabitha has ingested a large quantity of lead, which has interfered with the normal functions of the neurotransmitters in her brain. Which of the following neurotransmitters is incorrectly matched with its predominant function?

An action potential may not make it to the axon terminal.

Tabitha's symptoms indicate a problem with her nervous system. If the myelin on Tabitha's neurons is damaged, which of the following would happen?

The neuron would be unable to generate action potentials.

Tetrodotoxin is a toxin that blocks voltage-gated sodium ion channels. What effect would this have on the function of neurons?

Only the voltage-gated sodium ion channels found in the gaps or nodes of Ranvier are activated.

The burning sensation in Tabitha's feet is carried into the CNS by small, unmyelinated axons. Which of the following is NOT occurring in those axons?

voltage-gated Na ion channels

The channels that open when the axolemma reaches threshold depolarization are the:

voltage-gated channels

The generation of an action potential in a neuron requires the presence what type of membrane channels?

Norepinephrine, Dopamine, Serotonin

Uncle Mel suffers from depression and is having trouble sleeping. Some medications can increase the amount of neurotransmitter in the synapse by preventing its re-uptake into the presynaptic neuron or its degradation. This increases the level of the neurotransmitter in the synapse and prolongs its effects. Select which neurotransmitters you think might be a good target for anti-depressant drugs.

somatic sensory division

Upon entering your house, you noticed the smell of cake baking in the oven. What division of the peripheral nervous system is responsible?

Norepinephrine

an excitatory neurotransmitter, it causes a pleasant mood, increased attentiveness in the brain, and also causes blood vessel vasoconstriction to increase blood pressure.

Dopamine

an excitatory neurotransmitter, which helps with learning. Associated with a pleasant sensation and desire. Often nicknamed the "addiction" neurotransmitter due its association with addictions. This neurotransmitter also increases heart rate and force of contraction, but is toxic to the heart muscle.

(1) An action potential arrives at the synaptic terminal (2) Calcium channels open (3) Vesicals containing neurotransmitter fuse (4) Neurotransmitter molecules diffuse (5) The neurotransmitter molecules bind

identify the sequence of events that occurs at a synapse.

Endorphins

these peptides decrease the sensation of pain, and are often known as the "body's natural opiates."

continuous conduction

Action potential propagation in unmyelinated axons happens via: View Available Hint(s)

1..Threshold stimulusNa+ channels open2..Na+ influxDepolarization3.Na+ channels close4..K+ effluxRepolarization5.HyperpolarizationK+ channels close

Action potentials (nerve impulses) are changes in the membrane potential that, once started, will affect the entire excitable membrane. The first action potential is usually generated at the initial segment of the neuron's axon. This activity will test your understanding of the sequence of events that occur at the membrane of the initial segment of the axon during generation of an action potential.

-Opening of voltage-gated Na+ channels Opening of voltage-gated Na+channels-Na+ ion flow into the neuron increases N a + ion flow into the neuron increases-Depolarization of the membrane to +30 mV-K+ ion flow out of the neuron increases K + ion flow out of the neuron increases-Repolarization of The membrane

Arrange the following events in the correct order, from left to right, with respect to the function of the channels, ion permeability, and changes in membrane potential.

Chance of recovery of the damaged neurons is minimal. Ganglia is a group of cell bodies in the PNS. If they are damaged then we lose the lifeline of the neurons.

Ms. Karabekian suffers a vertebral fracture that damages many ganglia, then loses feeling in much of her leg. What is likely to occur?

hyperpolarization

The relative refractory period is caused by:

Herion

This drug binds to opioid receptors, which normally bind endorphins. This decreases pain and causes euphoria.

Ecstasy (MDMA)

This drug causes an increase in happiness and feeling good. It blocks the removal of serotonin from the synapse.

Cocaine

This drug increases alertness and causes a sensation of a "rush." It blocks the removal of dopamine from a synapse. Because dopamine also affects the heart, individuals who use this drug have an increased risk of heart attack and sudden death.

Alchohol

This drug mainly increases GABA to have an inhibitory effect on the brain.

Melatonin

Uncle Mel mentioned having difficulty sleeping. If he was prescribed a medication that targeted serotonin, such as a SSRI (selective serotonin reuptake inhibitor), it would also help with sleep. There is another chemical secreted in the brain that causes sleepiness. It is characterized as a hormone rather than a neurotransmitter. Name this hormone.

Brain injury leads to extensive debris in the area. Microglia mitotically divided into large numbers right before death and aggregated to clean up the damaged area.

When a pathologist performs an autopsy on a person who died of brain injury, why would he/she find large numbers of microglia?

facilitate the formation of the blood-brain barrier

Which of the following is a function of astrocytes?

Ca2+

Which of these ions triggers exocytosis of synaptic vesicles