Textbook Question
What is the difference between temporal summation and spatial summation?
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Ch. 12 Nervous Tissue
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011
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Table of contents
- Ch. 1 An Introduction to Anatomy and Physiology25
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization29
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure33
- Ch. 7 The Axial Skeleton11
- Ch. 8 The Appendicular Skeleton17
- Ch. 9 Joints13
- Ch. 10 Muscle Tissue12
- Ch. 11 The Muscular System28
- Ch. 12 Nervous Tissue18
- Ch. 13 The Spinal Cord, Spinal Nerves, and Spinal Reflexes22
- Ch. 14 The Brain and Cranial Nerves20
- Ch. 15 Sensory Pathways and the Somatic Nervous System17
- Ch. 16 The Autonomic Nervous System and Higher-Order Functions30
- Ch. 17 The Special Senses15
- Ch. 18 The Endocrine System21
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation26
- Ch. 22 The Lymphatic System and Immunity25
- Ch. 23 The Respiratory System4
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes30
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance17
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011Not the one you use?Change textbook
Chapter 12, Problem 17
Describe the steps involved in the generation of an action potential.
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Step 1: Resting membrane potential is established, typically around -70 mV, due to the distribution of ions (mainly Na\(\textsuperscript{+}\) and K\(\textsuperscript{+}\)) across the neuron's membrane and the activity of the sodium-potassium pump.
Step 2: A stimulus causes the membrane potential to reach the threshold level (usually around -55 mV), triggering the opening of voltage-gated sodium (Na\(\textsuperscript{+}\)) channels.
Step 3: Rapid depolarization occurs as Na\(\textsuperscript{+}\) ions rush into the cell, making the inside of the neuron more positive.
Step 4: At the peak of the action potential, voltage-gated sodium channels close and voltage-gated potassium (K\(\textsuperscript{+}\)) channels open, allowing K\(\textsuperscript{+}\) ions to exit the cell, initiating repolarization.
Step 5: The membrane potential returns toward the resting level (repolarization), sometimes overshooting to cause hyperpolarization, before the sodium-potassium pump and leak channels restore the resting membrane potential.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Resting Membrane Potential
The resting membrane potential is the electrical charge difference across the neuron's membrane when it is not transmitting a signal, typically around -70 mV. It is maintained by ion gradients, primarily through the sodium-potassium pump and selective permeability to ions, setting the stage for action potential initiation.
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Resting Membrane Potential
Depolarization and Threshold
Depolarization occurs when a stimulus causes the membrane potential to become less negative, reaching a critical threshold (usually around -55 mV). This triggers voltage-gated sodium channels to open, allowing Na+ ions to rush into the cell, initiating the rising phase of the action potential.
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Repolarization and Hyperpolarization
After the peak of the action potential, voltage-gated sodium channels close and potassium channels open, allowing K+ to exit the cell, restoring the negative membrane potential (repolarization). Sometimes, the membrane potential becomes more negative than resting level (hyperpolarization) before stabilizing back to resting potential.
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Related Practice
Textbook Question
Why can't most neurons in the CNS be replaced when they are lost to injury or disease?
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What is the functional difference among chemically gated (ligand-gated), voltage-gated, and mechanically gated ion channels?
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What are the structural and functional differences among type A, B, and C fibers?
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Textbook Question
State the all-or-none principle of action potentials.
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Textbook Question
Describe the events that occur during nerve impulse transmission at a typical cholinergic synapse.
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