The Reflex Arc: Sensory, Relay and Motor Neurons - Biological Psychology [AQA ALevel]

Summary

This video explores the structure and function of neurons involved in the reflex arc, highlighting the rapid response system of the body. It describes the roles of sensory neurons, relay neurons, and motor neurons in detecting sensations and triggering reflex actions. The video explains the transmission of electrical and chemical signals and introduces concepts like the myelin sheath and synapse. It concludes with fascinating facts about the speed of different types of neurons, emphasizing the body's ability to react swiftly to potential dangers.

Takeaways

• 😀 Neurons are the cells responsible for quick reactions in the body, forming structures known as reflex arcs.
• 🧠 A reflex arc consists of three types of neurons: sensory neurons, relay neurons, and motor neurons.
• 🔵 Sensory neurons detect sensations and send electrical signals to the spinal cord.
• 🟣 Relay neurons, located in the spinal cord, process the incoming signals and pass them to motor neurons.
• 🟢 Motor neurons activate effectors, such as muscles, to produce a reflexive movement.
• ⚡ Myelin sheaths, formed by Schwann cells, protect neurons and enhance the speed of electrical signal transmission.
• 🔄 A sensation, such as pain, triggers a quick reflex that often bypasses the brain for immediate response.
• 🏃‍♂️ The fastest neurons, alpha motor neurons, transmit signals at speeds up to 119 meters per second.
• 🐢 Conversely, Type C neurons transmit pain signals slowly, at approximately one mile per hour.
• 📚 The speaker offers additional educational resources, including over 140 videos on psychology.

Q & A

What is a reflex arc?

A reflex arc is a neural pathway that controls a reflex action. It involves sensory neurons, relay neurons, and motor neurons working together to produce a quick response to stimuli.

What are the three types of neurons involved in the reflex arc?

The three types of neurons involved in the reflex arc are sensory neurons, relay neurons (located in the spine), and motor neurons.

What role does the myelin sheath play in neuron function?

The myelin sheath, made of Schwann cells, protects the neuron and increases the speed of electrical signal transmission along the axon.

How do neurons transmit signals?

Neurons transmit signals through a process where an electrical signal travels along the dendrite and axon, converting to a chemical signal at the axon terminal to cross the synapse.

What happens when a sensory receptor detects a painful stimulus?

When a sensory receptor detects a painful stimulus, an electrical signal is sent through the sensory neurons to the relay neurons in the spinal cord, which then quickly communicate with motor neurons to initiate a reflex response.

What is proprioception?

Proprioception is the sense that allows the body to perceive its position and movement in space, enabling quick reactions to changes in the environment.

What is the fastest type of neuron in the body?

The fastest type of neuron in the body is the alpha motor neuron, which can transmit information at speeds of 119 meters per second, or 266 miles per hour.

What are type C neurons, and how do they differ from other neurons?

Type C neurons are responsible for transmitting pain signals and are among the slowest neurons, traveling at about one mile per hour due to their smaller size and lack of myelination.

Why does the brain receive information after the body has already moved during a reflex action?

The brain receives information after the body has moved to allow for immediate reflex responses, reducing the risk of tissue damage, as processing time in the brain is longer.

What educational resources are available for students studying psychology?

The video creator has made over 140 videos and offers a website full of resources to assist students in their psychology courses.