Lesson Notes By Weeks and Term v4 - SHS 1
ESSENTIALS FOR SURVIVAL
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ESSENTIALS FOR SURVIVAL
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Subject: General Science
Class: SHS 1
Term: 2nd Term
Week: 10
Grade code: 3.2.1.LI.4
Strand code: 2
Sub-strand code: 1
Content standard code: 3.2.1.CS.1
Indicator code: 3.2.1.LI.4
Theme: PROCESSES FOR LIVING
Subtheme: ESSENTIALS FOR SURVIVAL
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This lesson explores how our body sends messages with incredible speed, much like how we send a WhatsApp message. This internal communication system, the nervous system, allows us to react to our environment – from pulling our hand away from a hot kenkey ball to enjoying the taste of fresh groundnut soup. Understanding nerve impulses is fundamental to understanding how we think, feel, move, and survive. We will explore the "electrical wiring" of our bodies (neurons) and the "chemical messengers" that help pass information from one wire to the next.
This topic can be broken down into three main parts: A. The Messenger Cell (The Neuron) B. The Message Within the Cell (The Electrical Impulse) C. The Message Between Cells (The Chemical Transmission) A. The Messenger Cell: The Neuron
The basic unit of the nervous system is a specialised cell called a neuron (or nerve cell). Think of it as a single piece of electrical wire in the body. Its job is to carry messages. A typical neuron has three main parts: Dendrites: These are short, branched extensions that look like the branches of a tree. Their job is to receive signals from other neurons or from sensory receptors (e.g., in the skin or eyes). Cell Body (Soma): This is the main part of the cell, containing the nucleus and other organelles. It processes the signals received by the dendrites. Axon: This is a long, single fibre that extends from the cell body. Its job is to transmit the nerve impulse away from the cell body towards another neuron, a muscle, or a gland. Myelin Sheath: Many axons are covered in a fatty layer called the myelin sheath. This acts like the plastic insulation on an electrical wire. It speeds up the nerve impulse significantly and prevents the signal from leaking out. Axon Terminal: This is the end of the axon, where the signal is passed on to the next cell.
Analogy: Imagine a group of friends passing a secret message. The person who hears the message first is like the dendrites. Their brain processing the message is the cell body. Their mouth speaking the message to the next person is the axon. B. The Message Within the Cell: Generation of a Nerve Impulse (Action Potential)
A nerve impulse is essentially a wave of electrical activity that travels down the axon. It is also called an Action Potential. This process is both electrical and chemical, involving charged particles called ions (specifically sodium, Na⁺, and potassium, K⁺).