Neural Control of Movement

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Questions and Answers

What is the primary function of the cerebellum?

Controls thinking and memory

Coordinates muscle movements and maintains balance (correct)

Regulates heart rate and blood pressure

Transmits electrical impulses to muscles

Which part of the neuron integrates incoming signals?

Axon terminals

Dendrites

Axon

Cell body (correct)

What is resting membrane potential and its typical value?

Unstable electrical potential, varies constantly

Negative electrical potential, about -70 mV (correct)

Positive electrical potential, about +70 mV

Zero electrical potential, about 0 mV

What is the role of the sodium-potassium pump in a neuron?

It actively transports Na+ out and K+ into the cell Signup and view all the answers

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

Sodium (Na+) Signup and view all the answers

Which of these structures connects the brain to the spinal cord?

Brainstem Signup and view all the answers

What is primarily transported by the axon of a neuron?

Neurotransmitters and signals Signup and view all the answers

Which characteristic is not typical of a neuron at rest?

High concentration of Na+ inside the cell Signup and view all the answers

What initiates the action potential in a neuron?

A strong enough stimulus causing depolarization Signup and view all the answers

During which phase do sodium ions (Na+) rush into the cell?

Depolarization Signup and view all the answers

What is the purpose of opening voltage-gated potassium channels during repolarization?

To restore the negative charge inside the cell Signup and view all the answers

What occurs during hyperpolarization?

Potassium channels remain open longer than needed Signup and view all the answers

What is the function of synaptic vesicles in the presynaptic neuron?

To contain neurotransmitter chemicals Signup and view all the answers

Which structure separates the presynaptic and postsynaptic neurons?

Synaptic cleft Signup and view all the answers

What happens when the action potential reaches the axon terminals?

Synaptic vesicles dump their neurotransmitter chemicals Signup and view all the answers

Identify the term used for the neuron that receives the action potential across the synapse.

Postsynaptic neuron 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

This quiz explores the neural control of movement as part of the SSBR 304 course at UKZN. It covers key components of the nervous system, including the roles of the cerebrum, cerebellum, and brainstem. Test your understanding of how these areas interact to facilitate movement and maintain balance.