Neuroscience Chapter: Synapses and Signal Transmission

Questions and Answers

What role do calcium ions (Ca++) play in synaptic transmission?

They bind with protein receptors causing neurotransmitter release. (correct)

They cause depolarization in the post-synaptic terminal.

They are involved in the reuptake of neurotransmitters.

They inhibit neurotransmitter release.

Which structure is responsible for the release of neurotransmitters into the synaptic cleft?

Pre-synaptic membrane (correct)

Voltage-gated sodium channels

Post-synaptic neuron

Synaptic vesicles

What is the primary role of synapses in the nervous system?

They generate action potentials.

They provide structural support to neurons.

They integrate and process information. (correct)

They produce neurotransmitters.

What happens during depolarization of the pre-synaptic terminal?

Sodium influx occurs, leading to the opening of voltage-gated calcium channels. Signup and view all the answers

How do synapses influence weak signals in the nervous system?

They can either block or amplify weak signals. Signup and view all the answers

What is the primary function of synaptic vesicles?

To store neurotransmitters until they are released. Signup and view all the answers

What type of synapse primarily transmits signals through neurotransmitter substances?

Chemical synapse Signup and view all the answers

Which type of signals can modulate synaptic transmission?

Facilitatory and inhibitory signals from other areas in the nervous system. Signup and view all the answers

When a person touches a hot stove, what is the immediate response facilitated by the nervous system?

To lift the hand quickly. Signup and view all the answers

What characterizes synaptic clefts?

They are approximately 200-300 Å wide. Signup and view all the answers

Which component of the neuron has binding components for neurotransmitter receptors?

Post-synaptic neuron Signup and view all the answers

What defines the junction point between two neurons?

Synapse Signup and view all the answers

How do excitatory and inhibitory signals affect synaptic transmission?

They can either open synapses for transmission or close them. Signup and view all the answers

What is the process called where signals may be channeled in multiple directions?

Divergence Signup and view all the answers

What do synapses determine regarding the flow of nervous signals?

The directions signals will spread. Signup and view all the answers

What structure is crucial for the transmission of signals in chemical synapses?

Neurotransmitter Signup and view all the answers

What is the primary function of chemically activated ion channels in neurons?

To allow the influx and efflux of specific ions Signup and view all the answers

How does the Na-K pump affect the resting membrane potential (RMP) of neurons?

It extrudes more Na+ than K+ from the cell Signup and view all the answers

What is the Nernst potential for Na+ in this context?

+61 mv Signup and view all the answers

What effect does an increase in the number of receptors have in synaptic transmission?

It amplifies the response to neurotransmitters Signup and view all the answers

What is the primary role of inhibitory Cl- channels in neurons?

To hyperpolarize the neuron resulting in inhibition Signup and view all the answers

What characterizes the distribution of potentials in the soma during electrical events?

The potential changes uniformly at all points Signup and view all the answers

Which statement best describes the role of second messengers in neuronal signaling?

They modulate the activity of ion channels and receptors Signup and view all the answers

What is the concentration difference for K+ across the neuronal membrane as stated?

ECF: 4.5 meq/L, ICF: 120 meq/L Signup and view all the answers

Study Notes

Synapses and Signal Transmission

Synapses vary in efficiency, with some transmitting signals easily while others do so with difficulty.
Facilitatory and inhibitory signals influence synaptic transmission, either enhancing or blocking signal flow.

Mechanism of Action Potential

Action potentials in presynaptic terminals cause depolarization.
Influx of sodium (Na+) and calcium (Ca++) ions leads to neurotransmitter release.
Calcium ions bind to protein receptors, triggering exocytosis of neurotransmitters into the synaptic cleft.

Components of a Synapse

Presynaptic Terminals: Contain synaptic vesicles with neurotransmitters, mitochondria for ATP, and voltage-gated calcium channels.
Synaptic Cleft: Approximately 200-300 Å wide, the gap where neurotransmitters travel.
Postsynaptic Neuron: Contains two main receptor protein components—binding and channel components, crucial for signal processing.

Integrative Function of Synapses

Synapses selectively block weak signals while allowing stronger signals to pass.
They may amplify certain weak signals and channel them in multiple directions.
Example: Quick withdrawal from a hot surface stimulates both local and body-wide responses.

Types of Synapses

Chemical Synapses: Majority of CNS synapses use neurotransmitter substances for signal transmission.
Ion Channels: Two main types include excitatory Na+ channels and inhibitory K+ and Cl- channels.
Enzymatic functions manifest in receptor dynamics—whether increasing or decreasing receptor numbers.

Resting Membrane Potential (RMP)

RMP creates a negative interior in the neuronal soma due to the Na-K pump, which extrudes 3 Na+ for every 2 K+ ion transported inward.
Charged ions, such as protein ions and phosphate compounds, contribute to the negativity within the soma, preventing outward diffusion.

Distribution of Electrical Charge

A uniform distribution of potential exists within the soma; any change in potential affects intrasomal fluid uniformly.
High conductivity within the soma aids in efficient electrical current conduction due to its large diameter and electrolyte nature.

Excitatory Postsynaptic Potential (EPSP)

Key to understanding synaptic functions and how positive changes in membrane potential can lead to neuron activation.

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Description

Explore the complex world of synapses and their role in signal transmission in the nervous system. This quiz covers key concepts such as action potentials, neurotransmitter release, and the components of a synapse. Test your understanding of these fundamental mechanisms in neuroscience.