Page 31 - Biology_Form_3

Coordination in animals

Dendrites

Myelin sheath
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Node of Ranvier

Nucleus Schwan cell Axon
terminals

Cell body
Axoplasm
Axon
Figure 2.3: Structure of neurone

Activity 2.2: Types of neurones
Based on the structure and functions,
Comparing the structure of a typical
neurone and electrical cable there are three types of neurones which
are sensory, interneurone (intermediate or
Materials relay) and motor neurones.
Electric cable covered with plastic
insulators Sensory neurone

Procedure Sensory neurones are also known as afferent
neurones. These are neurones with a long
1. Take a piece of electric cable covered dendron and short axon as shown in Figure
with plastic insulator. 2.4. The cell body and dendrites of the
2. Cut it to observe its cross section. sensory neurones mostly lie outside the

Questions brain and spinal cord. They are responsible
1. Which part of the cable is equivalent for transmitting nerve impulses from the
sensory receptors to the central nervous
to a: system (CNS) for interpretation. Sensory
(a) axon? neurones have two long fibres, a dendron,

(b) myelin sheath? which conducts impulses from a sense
organ to the cell body of the neurone, and
2. Compare the structures and functions axon, which conducts impulses from the
of the electric cable and that of Figure cell body to the central nervous system.
2.3.

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