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Ch. 28 Nervous Systems
Taylor - Campbell Biology: Concepts & Connections 10th Edition
Taylor, Simon, Dickey, Hogan10th EditionCampbell Biology: Concepts & ConnectionsISBN: 9780136538783Not the one you use?Change textbook
All textbooksTaylor, Simon, Dickey, Hogan 10th EditionCh. 28 Nervous SystemsProblem 2
Chapter 28, Problem 2

The inside of the neuron has a lower concentration of positive ions than the outside of the neuron. Is the membrane potential positive or negative?

Verified step by step guidance
1
Understand the concept of membrane potential: Membrane potential is the electrical potential difference across a cell's plasma membrane, resulting from the distribution of ions (charged particles) on either side of the membrane.
Identify the key ions involved: In neurons, the key ions include sodium (Na+), potassium (K+), and chloride (Cl-). Sodium and potassium ions are positively charged, while chloride ions are negatively charged.
Recognize the distribution of ions: Typically, there is a higher concentration of Na+ outside the neuron and a higher concentration of K+ inside the neuron. This difference in ion concentration contributes to the membrane potential.
Relate ion concentration to membrane potential: Since the inside of the neuron has a lower concentration of positive ions (Na+ and K+) compared to the outside, this creates an electrical gradient. More positive charges outside the neuron make the inside relatively negative.
Determine the sign of the membrane potential: Given the higher concentration of positive ions outside and a lower concentration inside, the inside of the neuron is negatively charged relative to the outside. Thus, the membrane potential is negative.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Membrane Potential

Membrane potential refers to the electrical potential difference across a cell membrane, primarily due to the distribution of ions. In neurons, this potential is crucial for transmitting signals. A negative membrane potential indicates that the inside of the neuron is more negatively charged compared to the outside, which is typically the case at rest.
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Ion Concentration Gradient

An ion concentration gradient exists when there is a difference in the concentration of ions across a membrane. In neurons, the inside has a lower concentration of positive ions (like sodium) compared to the outside. This gradient is essential for the generation of action potentials and influences the overall membrane potential.
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Resting Membrane Potential

The resting membrane potential is the baseline electrical charge of a neuron when it is not actively transmitting signals, typically around -70 mV. This negative value results from the higher concentration of negatively charged ions and proteins inside the neuron, along with the selective permeability of the membrane to different ions, particularly potassium.
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Related Practice
Textbook Question
Test your understanding of the nervous system by matching the following labels with their corresponding letters: CNS, effector cells, interneuron, motor neuron, PNS, sensory neuron, sensory receptor, spinal cord, synapse.

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Textbook Question

Fill in the blanks to match some brain structures with their associated functions.

a. If the ___________ is severed, the right and left cerebral hemispheres cannot communicate.

b. The ___________ system helps store emotional memories.

c. Accounting for most of the weight of your brain is the highly folded ___________ ; it is the outer region of the ___________ .

d. The ___________ is responsible for hand-eye coordination.

e. The ___________ contains a cluster of neurons that function as the biological clock.

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Textbook Question
What causes a nerve signal to move from one end of a neuron along the length of the neuron to the other end? What is a nerve signal, exactly? Why can't it go backward? How is a nerve signal transmitted from one neuron to the next across a synapse? Write a short paragraph that answers these questions.
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Textbook Question

Joe accidentally touched a hot pan. His arm jerked back, and an instant later, he felt a burning pain. How would you explain the fact that his arm moved before he felt the pain?

a. His limbic system blocked the pain momentarily, but the important pain signals eventually got through.

b. His response was a spinal cord reflex that occurred before the pain signals reached the brain.

c. Motor neurons are myelinated; sensory neurons are not. The signals traveled faster to his muscles.

d. This scenario is not actually possible. The brain must register pain before a person can react.

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