Lesson Notes By Weeks and Term v4 - SHS 3
ANATOMY AND PHYSIOLOGY
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ANATOMY AND PHYSIOLOGY
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Subject: Biomedical Science
Class: SHS 3
Term: 1st Term
Week: 17
Grade code: 2.2.1.LI.2
Strand code: 2
Sub-strand code: 1
Content standard code: 2.2.1.CS.1
Indicator code: 2.2.1.LI.2
Theme: HUMAN BODY SYSTEMS
Subtheme: ANATOMY AND PHYSIOLOGY
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This lesson explores the incredible communication network within the human body: the nervous system. Imagine trying to send a message from Accra to Bolgatanga. You could send a letter by post (slow) or make a phone call (almost instant). The body has both slow (hormonal) and fast (nervous) systems. Today, we focus on the "phone call" – the nervous system, which allows us to think, feel, react, and move in fractions of a second. Understanding this is crucial because it explains everything from how we learn in class to how we quickly pull our hand away from a hot pot of banku.
A. The Basic Unit: The Neuron (Nerve Cell)
The nervous system is built from specialised cells called neurons. Think of them as the electrical wires of the body. A typical neuron has three main parts: Dendrites: These are short, branching extensions that look like tree branches. Their job is to receive signals from other neurons. Cell Body (Soma): This is the main part of the cell, containing the nucleus and other organelles. It integrates the signals received by the dendrites. Axon: This is a long, slender projection that transmits the electrical signal away from the cell body to other neurons, muscles, or glands. Many axons are covered by a fatty layer called the myelin sheath, which acts like the plastic insulation on an electrical wire. It speeds up the signal transmission significantly. The gaps in the myelin sheath are called Nodes of Ranvier. Axon Terminals: These are the small branches at the end of the axon that form connections (synapses) with other cells.
(Teacher's Note: Draw a large, labelled diagram of a motor neuron on the board while explaining these parts.)
``` (Dendrites) (Cell Body) (Axon) (Axon Terminals) /|\ _______ | /|\ -- -- / \ | -- -- (Synapse) \|/ | Nucleus O |=================O================= -- -- (Synapse) \_________/ (Myelin Sheath) (Node of Ranvier) \|/ (to next cell) ``` B. The Language of Neurons: The Nerve Impulse