Neurons - SS3 Biology Lesson Note

Neurons, also known as nerve cells, are the fundamental building blocks of the nervous system. They are specialized cells that transmit electrical and chemical signals, allowing for communication within the nervous system and between the nervous system and other parts of the body. Neurons have unique structural and functional properties that enable them to carry out their essential role in information processing and signal transmission. Key features of neurons include:

1.       Structure: Neurons have a distinctive morphology consisting of several specialized components:

a.       Cell Body (Soma): The cell body contains the nucleus and most of the cell's organelles. It processes incoming signals and integrates information.

b.       Dendrites: Dendrites are branching extensions that receive signals from other neurons or sensory receptors and transmit them toward the cell body.

c.       Axon: The axon is a long, slender projection that conducts electrical impulses away from the cell body. It ends in terminal branches that release neurotransmitters to transmit signals to other neurons, muscles, or glands.

d.       Myelin Sheath: Some neurons are surrounded by a myelin sheath, a fatty insulating layer formed by specialized cells called glia. The myelin sheath increases the speed and efficiency of signal conduction along the axon.

2.       Electrical Signalling: Neurons generate and transmit electrical impulses, known as action potentials, which allow for rapid communication. When a neuron is at rest, there is a voltage difference across its membrane called the resting membrane potential. Action potentials are produced when this membrane potential rapidly depolarizes and then repolarizes. This electrical signal travels down the axon, facilitating the transmission of information.

3.       Chemical Signalling: Neurons communicate with one another through synapses, which are specialized junctions where the axon terminals of one neuron connect to the dendrites or cell body of another neuron. Chemical messengers called neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron, transmitting the signal across the synapse.

4.       Functional Diversity: Neurons vary in their structure and function, allowing for specialized roles in information processing. Some neurons are sensory neurons that detect and transmit sensory information, while others are motor neurons that control muscle contractions. Interneurons, found within the CNS, facilitate communication between sensory and motor neurons and participate in complex information processing and integration.

 

Neurons work together to form intricate networks, allowing for the transmission and processing of information throughout the nervous system. This complex connectivity enables various functions, including sensory perception, motor control, learning, memory, and cognition. Understanding the properties and interactions of neurons is crucial for comprehending the mechanisms underlying brain function and the complexity of the nervous system.