2. 3.1 Response and
coordination
Changes may occur around us or inside of our
body
Organisms can detect the changes in the
environment and respond to the changes in
certain ways
The external environment- physical & chemical
conditions outside an organism and how these
conditions affect it(light,sound,smell,etc..)
The internal environment- physical & chemical
conditions of the tissue fluid surrounding the
tissues of an organism(body temperature, osmotic
pressure and blood glucose level)
3. The need for an organism to be
sensitive
The internal environment must be constant for
an organism to be healthy or survive
An organism cannot control its external
environment, can control internal env. to a
certain extent
4. Being able to respond enables an
organism:
To regulate its internal environment
Obtain and use resources, grow, reproduce,
and maintain stable internal conditions while
living in a constantly changing external
environment
5. Responses of humans, animals
and plants to stimuli
Stimulus – changes in the external and
internal environment
Receptor – detect the stimulus
Afferent neurone – carries the nerve impulse
to the integrating centre(central nervous
system) in the brain
Efferent neurone – carries the nerve impulse
from brain to the effector
Effector – reacts to cause a response
(muscles/glands)
6. Pathways of information due to
external stimuli
Example: Sound of doorbell
Stimulus
(sound of
doorbell)
Receptor in the
ear
INTERGRATING
CENTRE/CNS
(brain)
Effector
(muscles in
hand)
Response
(open the door)
7. Pathway of information due to
internal stimuli
Internal stimuli are detected by receptors
sensitive to changes within the body
The endocrine system and nervous system
control and coordinate functions in the body to
maintain a constant internal environment
through a negative feedback system
Negative feedback operates to counteract the
change in the internal environment to restore it
to normal
8. Body temperature
Integratin
g centre
(brain)
Effector
(skin and
endocrine
glands)
Response
(Activities to
increase
heat loss
from body
surface)
Normal body
temperature
Stimulus
(high body
temperature)
Receptors
in the skin
By negative
feedback
Lowers body
temperature
Rises due to
excess heat
Changes in body
temperature detected
by
9. Coordination
Is the process involved in the detection of
stimulus and the subsequent response of the
organism towards the stimulus
Involve nervous system and endocrine system
10. 3.2 Role of human nervous
system
Role of nervous system:
- Detect changes by receptors, process the
received sensory information and initiates the
response
- Helps us think and act consciously
- Stores information and allows us to learn from
past experiences
- Adapts the body to changes in the
environment
- Controls and coordinates the activities of all
other systems in the body
11. Organisation of nervous
system
NS is made up of :
1) Central nervous system [brain & spinal
cord]
2) Peripheral nervous system [cranial nerve &
spinal nerve]
12. Central nervous system
Control centre of the body
Consists of brain & spinal cord
Processes sensory information, making
decision and initiating responses
13. Peripheral nervous system
Is responsible for the communication between
the CNS and the rest of the body
Consists of all the nerves that branch out from
the CNS and connects it to the rest of the body
Cranial nerves – nerves that carry impulses to
and from the brain
Spinal nerves – nerves that carry impulses to
and from the spinal cord
14. Structure and function of the
brain
Brain weighs about 1.4kg
Consists of:
1. Cerebrum
2. Cerebellum
3. Medulla oblongata
4. Hypothalamus
5. Thalamus
6. Pituitary gland
15. 1. Cerebrum
The largest region,divided into the right and left
hemisphere
Each hemisphere has folds to increase the
surface area
The left H. controls the right side of the body while
the right H. controls the left side
Interprets information from receptors and controls
movement of skeletal muscles in VOLUNTARY
ACTION
Is the site of intelligence and carries out complex
mental processes such as learning, remembering
and making judgements
16. 2. Cerebellum
2nd largest region
Has two hemispheres
Coordinates the contraction of the muscles
and helps control BALANCE to produce
precise movements
17. 3. Medulla oblongata
Relays information between the spinal cord
and the brain
Controls INVOLUNTARY ACTIONS such as
heartbeat, breathing and blood circulation
Control reflex centre for heart rate, blood
pressure, blinking, sneezing, peristalsis,
vomiting, swallowing
18. 4. Thalamus
Receives information from all sensory
receptors and then transmits it to the proper
region of the cerebrum for further processing
19. 5. Hypothalamus
Control centre for recognition and analysis of
hunger,thirst,fatigue, anger and body
temperature
Controls the coordination and the nervous
system and endocrine system
20. 6. Pituitary gland
Is attached to hypothalamus
Connects the central nervous system with the
endocrine system
Produce many important hormones
21. Spinal cord
Is the link between the brain and the
peripheral NS
Consists of grey matter in the middle and white
matter around it
Spinal nerves arise from spinal cord
Each spinal nerve has a dorsal root (contains
afferent neuron) and ventral root (contains
efferent neurone)
CONTROL REFLEX ACTION