Unit 2, Part 1 Review - Module 9: Neurons

What is a neuron?

• A neuron is a nerve cell.

• A neuron is a type of muscle.

• A neuron is a blood vessel.

• A neuron is a bone cell.

Answer explanation

A neuron is a nerve cell responsible for transmitting information throughout the body. It is not a muscle, blood vessel, or bone cell, making the first choice the correct answer.

Tags

NGSS.MS-LS1-8

NGSS.MS-LS1-3

Which part of a neuron receives messages from other cells?

• Dendrites

• Axon

• Cell body

• Myelin sheath

Answer explanation

Dendrites are the parts of a neuron that receive messages from other cells. They act as the input channels, allowing the neuron to gather information from its environment and other neurons.

Which part of a neuron passes messages away from the cell body to other neurons, muscles, or glands?

• Axon

• Dendrite

• Nucleus

• Soma

Answer explanation

The axon is the part of a neuron that transmits messages away from the cell body to other neurons, muscles, or glands, making it essential for communication within the nervous system.

What is the function of the myelin sheath?

• The myelin sheath covers the axon of some neurons and helps speed neural impulses.

• It produces neurotransmitters for synaptic transmission.

• It generates electrical impulses in the neuron.

• It connects neurons to muscle fibers for movement.

Answer explanation

The myelin sheath is a protective covering around the axon of some neurons, which insulates the axon and significantly increases the speed of neural impulses, allowing for efficient communication between neurons.

What is the cell body (soma) of a neuron?

• The cell body (soma) is the cell's life support center.

• The cell body (soma) is the part that transmits signals to other neurons.

• The cell body (soma) is the structure that insulates the axon.

• The cell body (soma) is the gap between two neurons.

Answer explanation

The cell body (soma) is essential for the neuron's survival, housing the nucleus and organelles. It supports cellular functions, making it the cell's life support center, unlike other options that describe different neuron parts.

What is the action potential?

• The action potential is the electrical signal traveling down the axon.

• The action potential is a chemical released by the synapse.

• The action potential is the process of cell division in neurons.

• The action potential is the structure that insulates the axon.

Answer explanation

The action potential is the electrical signal that travels down the axon, allowing neurons to communicate. This distinguishes it from other options, which describe different aspects of neuronal function.

What is the threshold in neural transmission?

• The threshold is the level of stimulation required to trigger a neural impulse.

• The threshold is the maximum speed of a neural impulse.

• The threshold is the amount of neurotransmitter released at a synapse.

• The threshold is the distance between two neurons.

Answer explanation

The threshold in neural transmission refers to the minimum level of stimulation needed to initiate a neural impulse, making the first answer choice correct. The other options describe different aspects of neural function.

What is the all-or-none response in neurons?

• The all-or-none response means neural firing happens at full response or not at all.

• It means neurons can partially fire depending on stimulus strength.

• It refers to neurons firing only when two stimuli are present.

• It describes the gradual increase in neural response with increasing stimulus.

Answer explanation

The all-or-none response in neurons indicates that when a neuron fires, it does so at full strength or not at all, meaning there are no partial firings. This distinguishes it from other responses that vary with stimulus strength.

What is an excitatory signal?

• An excitatory signal is a neural impulse that results in the release of neurotransmitters that trigger action.

• An excitatory signal is a neural impulse that inhibits the release of neurotransmitters.

• An excitatory signal is a chemical that blocks neural communication.

• An excitatory signal is a signal that causes muscles to relax.

Answer explanation

An excitatory signal promotes action by causing the release of neurotransmitters, which facilitate communication between neurons. This is why the first choice is correct, as it accurately describes the function of excitatory signals.

What is an inhibitory signal?

• An inhibitory signal is a neural impulse that results in the release of neurotransmitters that depress/inhibit action.

• An inhibitory signal is a neural impulse that always excites the next neuron.

• An inhibitory signal is a type of hormone released during exercise.

• An inhibitory signal is a signal that increases the heart rate.

Answer explanation

An inhibitory signal is a neural impulse that leads to the release of neurotransmitters that inhibit or depress the action of the next neuron, making the first answer choice correct.