Biology

1. IGCSE
BIOLOGY
14
Co-ordination and
response

2. hormones
Sensitivity
stimuli detected
by
receptors
endocrine
system
nervous
system
effectors
carry
out
responses
electrical
impulses
The process of
coordination
any change in the external or internal
environment of the body
The way an organism reacts after
detecting a stimulus
– ability to detect stimuli and
carry out responses

4. 14.1
Nervous control in
humans

5. Syllabus Statements
Describe a nerve impulse as an electrical signal that passes along nerve cells called neurones
• Describe the human nervous system in terms of
– the central nervous system consisting of brain and spinal cord
– the peripheral nervous system – coordination and regulation of body functions
• Identify motor (effector), relay (connector) and sensory neurones from diagrams
• Describe a simple reflex arc in terms of receptor, sensory neurone, relay neurone, motor
neurones and effector
• Describe a reflex action as a means of automatically and rapidly integrating and coordinating
stimuli with the responses of effectors (muscles and glands)
• Define a synapse as a junction between two neurones
• Distinguish between voluntary and involuntary actions
• Describe the structure of a synapse, including the presence of neurotransmitter containing
vesicles, the synaptic cleft and neurotransmitter receptor molecules
• Describe how an impulse triggers the release of a neurotransmitter from vesicles into the
synaptic gap and how the neurotransmitter diffuses across to bind with receptor molecules, in
the membrane of the neurone after the synaptic gap, causing the impulse to continue
• State that in a reflex arc the synapses ensure that impulses travel in one direction only • State
that many drugs, e.g. heroin act upon synapses

6. Human Nervous System
PNS
-consists of nerves
-connect to all other parts of body
CNS
-integration and command center

7. Functions:
1. Control center (coordination and
regulation) of all body activities
2. Responds and adapts changes that
occur both inside an outside the body
(eg. Pain, temp etc.)

8. Basic Function of the Nervous System

9. Actions of the body
Nervous
System
In daily life, our body performs many different actions. These can be
categorized as – voluntary actions and involuntary actions.

10. A voluntary action is any action that we do out of our will or we do it consciously.
eg. Picking up a pen requires conscious thought and always involves the brain.
We drink water when we feel thirsty.

11. Reflex Arc
• Rapid +
automatic
• Integrate and
coordinate
stimuli with
responses
Five
essential
components
to the reflex
arc

12. Reflex Arc

13. receptor sensory neurone
effector motor neurone
interneurone
Reflex arc

14. 14 of 18 © Boardworks Ltd 2011
A reflex arc

15. Nerves
Nervous
System
Nerves form a network of pathways for conducting information throughout the
body. They transfer messages to and from the brain so that it can function
efficiently. There are three kinds of nerves – sensory, motor and mixed.

16. Structure of a Nerve