Neuroscience Graded Potentials Overview

Questions and Answers

What are graded potentials?

Brief short distance signals within a neuron, short-lived, localized changes in membrane potential.

What are action potentials?

Brief long distance signals within a neuron.

Why are graded potentials called 'graded'?

Because their magnitude varies directly with stimulus strength.

What triggers graded potentials?

A change in the neuron's environment that opens gated ion channels. Signup and view all the answers

What happens when you stimulate a single ion channel?

More sodium to flow through. Signup and view all the answers

Why do graded potentials have a short distance signal?

Because you are only activating one channel. Signup and view all the answers

Do graded potentials cause a large or small change in polarization?

Small change in polarization. Signup and view all the answers

What does the stimulus strength of a graded potential affect?

Membrane potential and distance of the signal. Signup and view all the answers

What can graded potentials cause?

Small depolarizations and hyperpolarizations. Signup and view all the answers

What is depolarization?

When membrane potential becomes less negative (closer to zero). Signup and view all the answers

What is hyperpolarization?

When the membrane potential becomes more negative (farther from zero). Signup and view all the answers

Where do we find graded potentials?

In our skin (sensory receptors and post-synaptic neurons). Signup and view all the answers

What are sensory receptors?

Specialized to respond to changes in their environment, which are called stimuli. Signup and view all the answers

What is sensation?

Awareness of the stimulus. Signup and view all the answers

What is perception?

Interpretation of the meaning of the stimulus. Signup and view all the answers

What happens when a sensory receptor is activated by an adequate stimulus?

Graded potentials that in turn trigger nerve impulses along the afferent PNS fibers to the CNS. Signup and view all the answers

What are mechanoreceptors?

Respond to mechanical force such as touch, pressure, vibration, and stretch. Signup and view all the answers

What do thermoreceptors respond to?

Changes in temperature. Signup and view all the answers

What do photoreceptors respond to?

Light. Signup and view all the answers

What do chemoreceptors respond to?

Chemicals in solution, smell, and taste. Signup and view all the answers

What do nociceptors respond to?

Potentially damaging stimuli that result in pain. Signup and view all the answers

How do graded potentials and action potentials work together to send information?

Graded potentials cause action potentials to fire when they pass the threshold of -55. Signup and view all the answers

What does multiple graded potentials equal?

Stimulus. Signup and view all the answers

What does a higher frequency of action potentials indicate?

The stronger the stimulus. Signup and view all the answers

How does the CNS know the difference between small and large stimuli?

The stronger the stimulus, the more stimulated neurons. Signup and view all the answers

Study Notes

Graded Potentials

Graded potentials are short-lived, localized changes in membrane potential occurring primarily in dendrites or the cell body of a neuron.
These changes can be depolarizations (less negative) or hyperpolarizations (more negative) and cause current flows that diminish with distance.
The term "graded" signifies that the magnitude of these potentials varies with the strength of the stimulus, allowing for diverse responses to environmental changes.
Graded potentials initiate when a stimulus triggers gated ion channels to open, allowing ion flow into the neuron.
Each activated ion channel enables sodium ions to enter, enhancing depolarization.
Graded potentials produce small changes in polarization, NOT large shifts in voltage.
The strength of the stimulus affects both the membrane potential and the distance the signal can travel.

Action Potentials

Action potentials are long-distance signals in neurons that follow graded potentials.
A graded potential must reach a threshold of -55 mV to trigger an action potential, marking the transition from local changes to a widespread signal.

Sensory Reception

Graded potentials occur in sensory receptors and post-synaptic neurons, where they respond to environmental changes (stimuli).
Sensation refers to the awareness of a stimulus, while perception is the interpretation of its significance.

Types of Receptors

Mechanoreceptors detect mechanical forces like touch and pressure.
Thermoreceptors respond to temperature changes.
Photoreceptors in the retina of the eye respond to light.
Chemoreceptors react to chemicals in solution, affecting smell and taste.
Nociceptors signal potentially damaging stimuli, leading to the sensation of pain.

Relationship Between Graded and Action Potentials

Graded potentials can trigger action potentials; when summed, multiple graded potentials contribute to exceeding the threshold needed to fire an action potential.
The frequency of action potentials correlates with stimulus strength—higher frequencies indicate stronger stimuli.
The central nervous system differentiates between small and large stimuli based on the number of neurons stimulated and the frequency of action potentials.

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Description

This quiz covers the essential concepts of graded potentials in neurons. Learn about the characteristics, significance, and differences between graded potentials and action potentials. Perfect for students studying neuroscience or physiology.