IB Biology 6.5 Neurons and Synapses Notes

Introduction

Neurons and synapses are fundamental components of the nervous system, responsible for transmitting and processing information throughout the body. This study note will delve into the structure and function of neurons, the nature of nerve impulses, and the mechanisms of synaptic transmission, as outlined in the International Baccalaureate (IB) Biology syllabus, particularly focusing on topic 6.5.

The Nervous System

The human nervous system consists of two main parts:

• Central Nervous System (CNS): Comprising the brain and spinal cord.
• Peripheral Nervous System (PNS): Comprising all the nerves outside the CNS.

The nervous system allows us to perceive our environment, respond to stimuli, and regulate bodily functions. Information is transmitted through the nervous system in the form of electrical impulses that travel along neurons.

Neurons: Structure and Function

Neurons are specialized cells designed to transmit information. They have several key features:

• Axon: A long, slender projection that conducts electrical impulses away from the neuron's cell body.
• Cell Body: Contains the nucleus and other organelles necessary for cell function.
• Dendrites: Branch-like structures that receive impulses from other neurons.

Types of Neurons

Neurons can be classified based on their function:

• Sensory Neurons: Transmit sensory information from receptors to the CNS.
• Motor Neurons: Transmit commands from the CNS to muscles and glands.
• Interneurons: Connect neurons within the CNS, facilitating communication between sensory and motor neurons.

Nerve Impulses