Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

11. Nervous Tissue and Nervous System

Properties of Graded and Action Potentials

Anatomy & Physiology

11. Nervous Tissue and Nervous System

Properties of Graded and Action Potentials

Previous problemNext problem

4:59 minutes

Problem 3

Textbook Question

Assume that an EPSP is being generated on the dendritic membrane. Which will occur?
a. Specific Na⁺ channels will open.
b. Specific K⁺ channels will open.
c. A single type of channel will open, permitting simultaneous flow of Na⁺ and K⁺.
d. Na⁺ channels will open first and then close as K⁺ channels open.

Verified step by step guidance

Understand the concept of an EPSP (Excitatory Postsynaptic Potential): EPSPs are depolarizations of the postsynaptic membrane caused by the flow of positively charged ions into the cell, making the neuron more likely to fire an action potential.

Recall that EPSPs are typically generated by the opening of ligand-gated ion channels, which allow the simultaneous flow of Na⁺ (into the cell) and K⁺ (out of the cell). This simultaneous flow results in a net depolarization because the influx of Na⁺ is greater than the efflux of K⁺.

Eliminate options that do not align with the mechanism of EPSPs: For example, specific Na⁺ channels opening alone (option a) or specific K⁺ channels opening alone (option b) would not result in the simultaneous ion flow characteristic of EPSPs.

Consider the role of a single type of channel permitting simultaneous flow of Na⁺ and K⁺ (option c). This matches the mechanism of EPSPs, as ligand-gated channels typically allow both ions to pass through simultaneously.

Evaluate the incorrectness of option d: Na⁺ channels opening first and then closing as K⁺ channels open describes the sequence of events during an action potential, not an EPSP. EPSPs involve simultaneous ion flow through a single type of channel.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

Excitatory Postsynaptic Potential (EPSP)

An EPSP is a temporary depolarization of a postsynaptic membrane potential caused by the flow of positively charged ions into the neuron. This occurs when neurotransmitters bind to receptors on the dendritic membrane, leading to the opening of ion channels, primarily sodium (Na⁺) channels. The influx of Na⁺ ions makes the inside of the neuron more positive, moving the membrane potential closer to the threshold for action potential generation.

Ion Channel Dynamics

Ion channels are specialized proteins that allow ions to flow across the cell membrane. In the context of EPSPs, specific Na⁺ channels open in response to neurotransmitter binding, allowing Na⁺ ions to enter the neuron. The dynamics of these channels are crucial, as they determine the timing and sequence of ion flow, which influences the overall excitability of the neuron and the generation of action potentials.

Depolarization and Repolarization

Depolarization refers to the process where the membrane potential becomes less negative (more positive) due to the influx of Na⁺ ions during an EPSP. Following this, repolarization occurs when K⁺ channels open, allowing K⁺ ions to exit the neuron, restoring the negative membrane potential. Understanding these phases is essential for grasping how neurons communicate and process signals through changes in membrane potential.

Watch next

Master Graded and Action Potentials with a bite sized video explanation from Bruce Bryan

Start learning