Neural Control of Movement

Questions and Answers

What is the primary role of the axon in a neuron?

To receive signals from other neurons

To integrate incoming signals

To transmit electrical impulses away from the cell body (correct)

To release neurotransmitters

Which part of the brain is responsible for coordinating muscle movements and maintaining balance?

Cerebellum (correct)

Cerebrum

Spinal Cord

Brainstem

What is the typical resting membrane potential of a neuron?

-70 mV (correct)

+70 mV

-90 mV

0 mV

What component of the nervous system is primarily responsible for controlling automatic functions necessary for survival?

Brainstem Signup and view all the answers

Which ion has a higher concentration in the extracellular fluid compared to the cytosol?

Sodium (Na+) Signup and view all the answers

What mechanism is responsible for maintaining the sodium and potassium concentration gradients across a neuron's membrane?

Sodium-potassium pump Signup and view all the answers

Which part of the neuron receives signals from other neurons?

Dendrites Signup and view all the answers

Which ion concentration is typically low in the intracellular fluid compared to the extracellular fluid?

Sodium (Na+) Signup and view all the answers

What initiates the depolarization phase of an action potential?

A stimulus causes the cell membrane to become less negative Signup and view all the answers

What is the primary action that occurs during the repolarization phase of the action potential?

Eflux of K+ ions Signup and view all the answers

What effect does hyperpolarization have on the membrane potential?

It makes the membrane potential less negative than resting potential Signup and view all the answers

What role do synaptic vesicles play in neurotransmission?

They contain neurotransmitter chemicals that are released into the synaptic cleft Signup and view all the answers

Which part of the neuron sends the action potential across the synapse?

The presynaptic neuron Signup and view all the answers

Which of the following correctly describes the synaptic cleft?

The narrow gap separating presynaptic and postsynaptic neurons Signup and view all the answers

What triggers the opening of voltage-gated sodium channels?

The reaching of threshold potential Signup and view all the answers

What does the term 'threshold potential' refer to?

The membrane potential needed to trigger an action potential Signup and view all the answers

Study Notes

Nervous System Overview

Central Nervous System (CNS) consists of the brain and spinal cord.
Brain Structure
- Cerebrum: Responsible for thinking, memory, emotions, and voluntary movement.
- Cerebellum: Coordinates muscle movements, posture, and balance.
- Brainstem: Connects brain to spinal cord; regulates automatic functions such as breathing, heart rate, and blood pressure.
Spinal Cord: Transmits messages between the brain and the body; coordinating reflexes.

Neuron Anatomy

Neurons are specialized cells for transmitting information.
Dendrites: Receive signals from other neurons and convey them to the cell body.
Cell Body: Contains the nucleus and integrates incoming signals.
Axon: Transmits electrical impulses away from the cell body.
Axon Terminals: Release neurotransmitters to communicate with other cells.

Ion Concentration in Human Fluids

Potassium (K+): High in cytosol (~140 mM), low in interstitial fluid (~4-5 mM).
Sodium (Na+): Low in cytosol (~10-15 mM), high in interstitial fluid (~135-145 mM).
Chloride (Cl-): Low in cytosol (~4-10 mM), high in interstitial fluid (~100-110 mM).
Calcium (Ca2+): Very low in cytosol (~0.0001 mM), higher in interstitial fluid (~1-2 mM).
Magnesium (Mg2+): Higher in cytosol (~0.5-1.0 mM), lower in interstitial fluid (~1-2 mM).
Proteins: High concentration in cytosol, lower in interstitial fluid.

Resting Membrane Potential

Neuron at rest has a negative potential of ~-70 mV.
High Na+ concentration outside the cell and high K+ concentration inside.
Maintained by sodium-potassium pump (3 Na+ out, 2 K+ in) using ATP.

Action Potential

A rapid change in electrical potential allowing signal transmission.
Depolarization:
- Triggered by a strong stimulus, reaching threshold potential (~-55 mV).
- Voltage-gated sodium channels open, Na+ floods in, raising membrane potential to ~+30 mV.
Repolarization:
- Sodium channels close; potassium channels open.
- K+ exits, restoring negative charge inside the cell.

Hyperpolarization

K+ channels stay open longer, causing a more negative membrane potential than resting state.

Synapse Structure

Communication between neurons occurs across synapses.
Presynaptic Neuron: Sends the action potential; contains presynaptic terminals with synaptic vesicles.
Postsynaptic Neuron: Receives action potential; has postsynaptic receptors.
Synaptic Cleft: The gap between presynaptic and postsynaptic neurons.
Upon reaching axon terminals, synaptic vesicles release neurotransmitters into the synaptic cleft.

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Description

Explore the intricacies of the neural control of movement in this quiz tailored for SSBR 304 at UKZN. Understand the functions of the cerebrum, cerebellum, and brainstem in relation to voluntary movements, coordination, and automatic functions. Test your knowledge on the nervous system and its components.