Q: Which equation best represents the threshold for action potential generation?

$ V_{threshold} \approx -55 \text{ mV} $

Question 1

Which of the following best describes the difference between hormones and neurocrines?

Accepted Answer

Hormones are released by endocrine glands and travel through the bloodstream to distant targets, while neurocrines (including neurotransmitters, neuromodulators, and neurohormones) are released by neurons and may act locally or systemically.

Question 2

A ligand is defined as:

Accepted Answer

A molecule that binds to a receptor to initiate a cellular response.

Question 3

Which equation best represents the resting membrane potential established by passive ion channels?

Accepted Answer

$ V_{rest} = \frac{g_{K^+}E_{K^+} + g_{Na^+}E_{Na^+} + g_{Cl^-}E_{Cl^-}}{g_{K^+} + g_{Na^+} + g_{Cl^-}} $

Question 4

Which of the following is TRUE regarding the trigger zone of a neuron?

Accepted Answer

It is the region where graded potentials are summed and, if threshold is reached, an action potential is initiated.

Question 5

During the rising phase of an action potential, which channels are primarily open and which ions are moving?

Accepted Answer

Voltage-gated Na$^+$ channels are open, and Na$^+$ ions are moving into the cell.

Question 6

Which glial cell is responsible for forming myelin in the central nervous system?

Accepted Answer

Oligodendrocyte

Question 7

What is the main function of the sodium-potassium exchange pump in neurons?

Accepted Answer

To maintain the resting membrane potential by actively transporting Na$^+$ out and K$^+$ in.

Question 8

Which of the following best describes saltatory conduction?

Accepted Answer

Action potentials jump from one node of Ranvier to the next along a myelinated axon.

Question 9

Which statement about the absolute refractory period is correct?

Accepted Answer

It occurs when voltage-gated Na$^+$ channels are inactivated and cannot be reopened.

Question 10

Which equation best represents the threshold for action potential generation?

Accepted Answer

$ V_{threshold} \approx -55 	ext{ mV} $

Question 11

Which of the following is a function of astrocytes in the CNS?

Accepted Answer

Providing structural support and maintaining the blood-brain barrier

Question 12

Which structural type of neuron is most commonly found in sensory neurons of the peripheral nervous system?

Accepted Answer

Pseudounipolar neuron

Question 13

Which of the following best describes the difference between graded potentials and action potentials?

Accepted Answer

Graded potentials decrease in strength as they spread, while action potentials maintain their strength.

Question 14

Which of the following is TRUE regarding the termination of neurotransmitter activity?

Accepted Answer

Neurotransmitter activity can be terminated by enzymatic breakdown, reuptake into the presynaptic cell, or diffusion away from the synaptic cleft.

Question 15

Which of the following best describes the role of glutamate in long-term potentiation?

Accepted Answer

Glutamate activates NMDA receptors, leading to increased synaptic strength and memory formation.

Question 16

Which of the following is a correct example of spatial summation?

Accepted Answer

Multiple graded potentials from different locations on the neuron combine to reach threshold.

Question 17

Which of the following is TRUE about the efferent pathway in the nervous system?

Accepted Answer

It transmits signals from the CNS to effector organs such as muscles and glands.

Question 18

Which of the following is a function of microglial cells in the CNS?

Accepted Answer

Phagocytosing pathogens and debris

Question 19

Which of the following best describes the difference between an electrical synapse and a chemical synapse?

Accepted Answer

Electrical synapses transmit signals directly via gap junctions, while chemical synapses use neurotransmitters to transmit signals across a synaptic cleft.

BIO 305 Study Guide: Neurons and Nervous System Organization

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