Lesson Notes By Weeks and Term v4 - SHS 3
MAMMALIAN SYSTEMS
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MAMMALIAN SYSTEMS
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Subject: Biology
Class: SHS 3
Term: 2nd Term
Week: 17
Grade code: 3.4.1.LI.4
Strand code: 4
Sub-strand code: 1
Content standard code: 3.4.1.CS.1
Indicator code: 3.4.1.LI.4
Theme: SYSTEMS OF LIFE
Subtheme: MAMMALIAN SYSTEMS
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This lesson explores the two main control and coordination systems in mammals: the nervous system and the hormonal (endocrine) system. Think of them as the body's communication network. The nervous system is like a high-speed internet connection (sending instant messages), while the hormonal system is like the postal service (sending letters that have a longer-lasting effect). Understanding how these systems work alone and, more importantly, *together*, is fundamental to understanding our health.
A. What is Coordination? Coordination is the process by which all the different organs and systems in the body work together efficiently to produce an appropriate response to an internal or external stimulus. For the body to function as a single, healthy unit, its parts must communicate. This communication is handled by the nervous and hormonal systems. B. The Nervous System: The Body's High-Speed Network
The nervous system provides rapid, short-lived coordination. It uses specialised cells called neurons to transmit electrical signals, called nerve impulses. The Neuron (Nerve Cell): The Basic Unit A neuron is the fundamental unit of the nervous system. There are three main types: Sensory Neurons: Transmit impulses from sense organs (receptors) like the skin or eyes to the central nervous system. Relay (or Connector) Neurons: Found within the central nervous system, they link sensory and motor neurons. Motor Neurons: Transmit impulses from the central nervous system to effectors (muscles or glands) to bring about a response. Divisions of the Nervous System Central Nervous System (CNS): The processing centre. It consists of the brain and the spinal cord. Peripheral Nervous System (PNS): The network of nerves that connect the CNS to the rest of the body (limbs and organs). How Nervous Coordination Works: The Reflex Arc A reflex action is an involuntary, rapid response to a stimulus. The pathway taken by the nerve impulse is called a reflex arc.