2. Learning outcomes :
1. List the changes in external and
internal environment faced by
organism
2. State why organisms have to be
sensitive to changes in internal and
external environment
3. Clarify through examples the
meaning of stimulus and response
3. Learning outcomes :
4. State the main components and pathways
involved in detecting and responding to
changes in external environment
5. State the main components and pathways
involved in detecting and responding to
changes in internal environment
6. Clarify through examples the meaning of
coordination
4. The changes which response in the body called STIMULI
STIMULI
External
(outside the body)
Internal
(inside the body)
Light, smell, taste, temperature,
pressure, touch, sound
-Sugar level in the blood
-Osmotic pressure of blood
-Body temperature
-pH of tissue fluid
6. Human / Animal
To enable them to
move, feel pain & taste
for safety
Adapt to environment
(ensure survival)
To protect them from
harm / danger
Regulate internal
environment
(homeostasis)
Plant
Receive more sunlight
for photosynthesis
Obtain better support
Obtain enough water
7. NO ITEM DEFINITION
1 Receptors Group of cells that detect stimulus
2 Effector Produce response to stimuli
3 Response Way of an organism react after a stimulus is
detected
4 Coordination Response that appropriate towards the stimuli
Coordination
& Response
Nervous
system
Endocrine
system
9. 1: RECEPTOR (in sensory organs)
detects the stimulus & triggers a nerve
impulse (NI) to be produced in
afferent neurone (AF)
2: AF carries the NI to the INTEGRATING
CENTRE ( in the brain)
3: Brain interprets the information &
send out another NI
4: Efferent neurone (EN) carries the NI
from brain to the EFFECTOR
(muscles/glands)
5: that reacts to RESPONSE to the
STIMULUS
10. Pathways Of Information Due To External Stimuli
Stimulus
(Sound of car horn)
Receptor in the ear
Integrating centre
(Brain)
Response
(Move away from the
incoming car)
Effector
(Muscles in leg)
11. To regulate the internal environment so that it is at an
optimum condition.
Homeostasis–regulation of the internal environmentso that
equilibrium is maintained.
Involves negative feedback
When a factor in the internal environment increase above
normal range, negative feedback will occur to lower it.
13. Stimulus
(High body temperature)
Temperature sensitive
cells in the
hypothalamus
Thermoregulatory centre
at hypothalamus
(Brain)
Response
(Increase heat loss)
Effectors
(Skin and endocrine
glands)
15. Integrating centre
(Brain)
Receptors
(in hypothalamus)
Effector
(pancreatic glands)
Response
(activities to decrease
high glucose level)
Stimulus
(high glucose level
in the blood)
Normal glucose level
in the blood
A change in blood sugar
level is detected
By negative
feed back
Glucose level
is lowered
16. Is a process involved in the detection of stimulus & the
subsequent response of the organism towards stimulus
It involves both the nervous system & endocrine system