Neuron Structure and Function Quiz

Neuron Structure and Function: Input and Output

• Neurons receive input through sensory transduction, converting external stimuli (light, sound, touch, chemicals) into electrical signals.

Synaptic Transmission

• Neurotransmitters are released from vesicles at the pre-synaptic terminal.
• Neurotransmitters bind to receptors on the post-synaptic terminal, activating the neuron if the threshold is reached.
• This process is analogous to a "lock and key" mechanism.

The Action Potential

• An action potential is a rapid change in electrical potential across the neuron's membrane.
• Neurotransmitter binding opens ion channels, allowing ions to flow.
• This triggers a cascade that leads to depolarization and, if sufficient, the neuron "fires."
• Repolarization occurs, followed by a recovery period.

Saltatory Conduction

• Action potentials jump between nodes of Ranvier.
• Myelin sheaths insulate axons, preventing ion leakage.
• This significantly speeds up signal transmission.

Multiple Sclerosis

• Multiple sclerosis is an autoimmune disease that damages the myelin sheath.
• This leads to various symptoms, including numbness, impaired vision, paralysis, and dizziness in the sensory and motor system.

Measuring Neuron Transmission

• Direct measurement of individual electrons in neurons is not possible due to their small size.
• Local field potentials allow measurement of a small group of neurons, making it possible to detect neural activity in humans.
• Single-neuron recordings are possible in some animal models (e.g., mice).

Types of Neurons

• Sensory neurons receive input from sensory receptor cells directly.
• Motor neurons transmit signals to muscles.
• Amyotrophic lateral sclerosis (ALS) is a motor neuron disease. This devastating neurological disorder causes the motor neurons to degenerate, leading to weakness, paralysis, and ultimately death.

The Reflex Arc (Knee-Jerk Reflex)

• A basic reflex arc provides a simple way to measure neuron function.