1 The simplest type of animal behaviour is a reflex action in which the stimulus brings
about an automatic, involunatary, and stereotyped response. This is an unlearnt
behaviour. Reflex actions are innate and depend on nerve pathways that are inherited.
Many reflex actions, such as withdrawal of the hand from a hot object, are protective.
2 The nerve pathway that transmits information rapidly from a receptor
to an effector is called a reflex arc. Reflex arcs vary in complexity.
The one that removes a hand from a hot object has three neurines;
2.1 A sensory neurone;
that carries information
recpetors to the CNS
2.2 A motor neurone; that
carries information to
an effector neurone
2.3 An interneurone; in the CNS between the sensory and motor
neurone. It is also called the relay or association neurone because
it makes synaptic connections with nerves that pass upwards into
the assoiciation areas of the brain. These connections enable the
brain to modify a reflex action, but it cannot stop it completely
because information is transmited along the reflex arc too quickly
3 Fixed action patterns (FAP) are complex forms of stereotype
behaviour characterised by relatively fixed patterns of
coordinated movements. FAPs occur during nest-building in
birds and the suckling response of newborn babies. the are
brought about by specific stimuli called sign stimuli.
4 FAPs are largely innate responses but
they differ from relex actions in that they
may vary according to the precise
conditions in which the sign stimuli are
presented, and they can also be modified