Question 1

Which of the following is true of sensory neurons?

Accepted Answer

Sensory neurons are responsible for gathering information from the environment (such as touch, sound, light, etc.) and conveying this information into the central nervous system for processing. This allows the organism to react to stimuli in its environment.

Question 2

Which of the following is a true statement about neuron type?

Accepted Answer

Sensory neurons are typically unipolar or bipolar, depending on their location and function in the body. This allows them to effectively transmit sensory information from the peripheral nervous system to the central nervous system.

Question 3

Which of the statements about cell membranes is correct?

Accepted Answer

Cell membranes contain specialized protein channels that regulate the passage of ions and molecules in and out of the cell, crucial for cell function and communication.

Question 4

Which of the following is true about the lipids that compose the cell membrane?

Accepted Answer

The cell membrane is composed of a lipid bilayer, where the hydrophilic (water-attracting) "heads" face the extracellular and intracellular fluids, and the hydrophobic (water-repelling) "tails" are oriented away from these fluids, towards each other. This arrangement is crucial for the membrane's function as a barrier and its fluidity.

Question 5

One function of the specialized protein channels in a cell membrane is to ______.

Accepted Answer

Specialized protein channels in a cell membrane are designed to selectively allow substances to enter or leave the cell, ensuring that essential nutrients can be absorbed and waste products can be expelled, while maintaining the cell's internal environment.

Question 6

Which of the following is true of the resting membrane potential?

Accepted Answer

The resting membrane potential is indeed the difference in electrical charge inside and outside an inactive neuron, typically negative inside compared to outside. This is due to the distribution of ions (such as sodium and potassium) across the neuron's membrane, which is not freely permeable but selectively permeable, primarily to potassium ions at rest.

Question 7

Which of the following is true of both chloride ions and anions?

Accepted Answer

Chloride ions are a specific type of anion, and all anions, by definition, carry a negative charge.

Question 8

______ are concentrated primarily outside of the neuron, in the extracellular fluid, which contributes to the negative resting membrane potential of neurons.

Accepted Answer

Sodium ions (Na+) are primarily found outside the neuron in the extracellular fluid. This distribution is crucial for the establishment and maintenance of the negative resting membrane potential of neurons, as the sodium-potassium pump actively transports sodium out of the neuron.

Question 9

When making dinner, you add salt to a pot of boiling water. At first, the salt remains in one spot, but eventually spreads throughout the water due to the ______.

Accepted Answer

The salt spreads throughout the water due to the force of diffusion, which is the movement of particles from an area of higher concentration to an area of lower concentration until they are evenly distributed.

Question 10

During a neuron's resting state, channels for potassium and sodium ions are ______.

Accepted Answer

During a neuron's resting state, potassium channels are open and sodium channels are closed. This allows potassium ions to flow out of the cell and sodium ions to flow into the cell, creating a negative charge inside the cell.

Question 11

The sodium-potassium pump forces sodium ions ______ and potassium ions into the cell.

Accepted Answer

The sodium-potassium pump actively transports sodium ions out of the cell and potassium ions into the cell, maintaining a gradient essential for various cellular processes.

Question 12

Which of the following can prompt an electrically gated ion channel in the cell membrane to open?

Accepted Answer

Electrically gated ion channels are primarily opened by changes in the electrical potential across the cell membrane. This change in voltage can cause the channel to change its conformation and open, allowing ions to pass through.

Question 13

______ gated ion channels open and close based on the presence of neurotransmitters or hormones.

Accepted Answer

Chemically gated ion channels open or close in response to the binding of neurotransmitters or hormones, which are chemical signals.

Question 14

Which of the following is true of local potential but not action potential?

Accepted Answer

Local potentials are decremental, meaning they decrease in strength as they move through the cell, unlike action potentials which maintain their strength.

Question 15

The change in electrical charge from -70 mV to the peak of the action potential is due to ______.

Accepted Answer

The change in electrical charge from -70 mV to the peak of the action potential is primarily due to the inflow of sodium ions (Na+). When an action potential is triggered, voltage-gated sodium channels open, allowing Na+ to rush into the neuron, causing the interior to become more positive.

Question 16

The change in electrical charge from the peak of +30 or +40 mV back to -70 mV is due to ______.

Accepted Answer

The change in electrical charge from the peak of +30 or +40 mV back to -70 mV during an action potential is due to the outflow of potassium ions (K+). This outflow is part of the repolarization phase, where the cell returns to its resting membrane potential after depolarization.

Question 17

What ionic movement is responsible for pulling the membrane potential back to a negative voltage during an action potential?

Accepted Answer

During an action potential, potassium ions (K+) move out of the cell to repolarize the membrane, bringing the membrane potential back to a negative voltage after the depolarization phase.

Question 18

Which of the following is a true statement about what occurs when an axon transmits an action potential?

Accepted Answer

An action potential involves the movement of ions across the axon's membrane, creating a wave of electrical change, but nothing physically moves down the axon itself.

Question 19

A neuron's cell membrane could become positive through either an inflow of positive ions or an outflow of negative ions. Why is the inflow of positive ions the most logical method for this depolarization?

Accepted Answer

The inflow of positive ions, such as sodium ions, is the most logical method for depolarization because the cell membrane is more permeable to sodium ions, and there are already many chloride ions outside the cell, making the inflow of positive ions more efficient for depolarization.

Question 20

Which of the following is true of action potentials in axons?

Accepted Answer

Many action potentials are generated next to each other along the length of an axon. This is because the depolarization at one segment of the axon triggers the depolarization of the next segment, creating a chain reaction that propagates the action potential along the entire length of the axon.

Quiz 2: Communication Within the Nervous System