Neuroscience Structure and Functions Quiz

Study Notes

Structure of a Neuron

Cell Body: Houses the nucleus crucial for neuron function.
Dendrites: Receive and conduct impulses towards the cell body ensuring communication with other neurons.
Axon: Transmits electrical impulses away from the cell body; often insulated by Schwann cells which form a myelin sheath.
Synapse: Junction where axon of one neuron meets the dendrite of another, facilitating signal transmission.

Multiple Sclerosis (MS) and Exercise Training

MS Overview: Autoimmune disease characterized by the destruction of myelin sheaths around axons, leading to impaired nervous system function.
Symptoms: Includes fatigue, muscle weakness, poor motor control, balance issues, and mental depression.
Exercise Benefits: Enhances functional capacity and overall quality of life for MS patients by potentially improving nervous system health.

Electrical Activity in Neurons

Excitability: Neurons can respond to stimuli and initiate an action potential.
Conductivity: Refers to the ability to transmit impulses along the axon.
Resting Membrane Potential: The negative internal charge of cells at rest, typically between -5 to -100 mV, and more specifically -40 to -75 mV in neurons.

Factors Influencing Resting Membrane Potential

Membrane Permeability: Influenced by ion concentrations particularly sodium (Na+), potassium (K+), and chloride (Cl-).
Sodium-Potassium Pump: Actively maintains resting potential by moving 2 K+ ions into the cell and 3 Na+ ions out, countering diffusion of K+.

Transmission of Neural Messages

Action Potential: Initiated when a strong enough stimulus depolarizes a neuron, causing Na+ channels to open and Na+ to flow in, making the inside more positive.
Repolarization: Process of restoring resting potential, involves K+ rapidly leaving the cell as Na+ channels close.
All-or-None Law: Impulse either occurs fully or not at all, traveling the full length of the neuron once started.

Neurotransmitters and Synaptic Transmission

Synapse Functionality: Small gap where neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron, leading to depolarization.
Excitatory Neurotransmitters: Promote neural activation; can cause excitatory postsynaptic potentials (EPSPs) via temporal and spatial summation.
- Temporal Summation: Rapid succession from one neuron increases depolarization.
- Spatial Summation: Combined inputs from multiple neurons add together.

Inhibitory Neurotransmitters

Inhibitory Postsynaptic Potentials (IPSP): Hyperpolarize the neuron, making it more resistant to depolarization, which inhibits neural transmission.

Sensory Information and Reflexes

Proprioceptors: Monitor body position and movement situated in joints and muscles.
Kinesthesia: Awareness of body parts' position and limb movement speed.

Joint Proprioceptors

Free Nerve Endings: Commonly found receptors, sensitive to touch and pressure, adapt after initial activation.
Golgi-Type Receptors: Located in ligaments, functionally similar to free nerve endings.
Pacinian Corpuscles: Located around joints, detect joint rotation rates.

Muscle Proprioceptors

Muscle Spindle: Senses changes in muscle length and shortening rate.
Golgi Tendon Organ (GTO): Monitors force in muscles and prevents injury via reflex relaxation.

Muscle Spindle Functionality

Intrafusal Fibers: Parallel to regular muscle fibers (extrafusal), stimulated by gamma motor neurons.
Stretch Reflex: Initiated when muscle spindles detect stretch, leading to muscle contraction (knee-jerk reflex).

Golgi Tendon Organ (GTO) Reflexes

Detects tension in tendons and sends signals to the spinal cord.
Reflex action causes inhibitory signals to alpha motor neurons, resulting in muscle relaxation to prevent possible injuries.

Description

This quiz covers the structure and functions of neurons, including the roles of dendrites, axons, and synapses. It also explores clinical applications, focusing on the benefits of exercise training for multiple sclerosis patients. Test your knowledge on important concepts in neuroanatomy and physiology.