Nervous System Overview

Introduction

• Large multicellular organisms, such as humans, require communication between body parts for coordinated behavior and responses.
• Two main organ systems facilitate this: the nervous system and the endocrine system.

Components of the Nervous System

Neurons (Nerve Cells)

• Varied types but share common features:
  • Long, thin structure with branch connections.
  • Adapted to carry electrical impulses.
  • Biological equivalent of wires carrying currents.

Synapse

• Connection point between neurons.
• Electrical impulse triggers chemical release, diffusing across the gap to the next neuron.
• Chemical triggers a new electrical impulse in the next neuron, continuing the signal.

Central Nervous System (CNS)

• Composed of the brain and spinal cord.
• Responsible for processing sensory information and sending out responses.
• Receives information via sensory neurons from receptors throughout the body (e.g., temperature changes, carbon dioxide levels).
• Sends responses via motor neurons to effectors (muscles or glands).

Reflex Arc

• Nerve pathway underlying unconscious reflexes (e.g., withdrawing a hand from a hot object or blinking).
• Reflexes are rapid and automatic, aiding in injury prevention.

Example of a Reflex Arc

• Stimulus: Pressure from a sharp object detected by skin receptors.
• Sensory Neuron: Carries impulse from the finger to the spinal cord.
• Relay Neuron: Transfers impulse within the spinal cord.
• Motor Neuron: Carries impulse from the spinal cord to an effector (e.g., bicep muscle), triggering contraction.
• Synapses: Chemical signals facilitate transmission between neurons.

Additional Resources

• Videos, questions, flashcards, exam questions, and progress tracking available on cognito.org.
• Free sign-up for resources and browsing available on their website and YouTube channel.