CHAPTER 3 COORDINATION AND RESPONSE

CHAPTER 3:

Coordination

and

Response

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3.1 HOMEOSTASIS IN LIVING THINGS

HOMEOSTASIS ??

Maintenance of the internal

environment in the body of an

organism to be in a balanced and

stable condition

Temperature Water pH Blood pressure

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HOMEOSTASIS IN HUMANS

Internal environments that involved in regulation include:

Water Mineral content This process is also known as
osmoregulation.

This process takes place in the
kidneys

Body temperature

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HOMEOSTASIS IN HUMANS

Homeostasis involves two major actions:

Detect imbalances Changes outside or inside the body are
detected by receptors and interpreted by the

brains' control center

Corrective mechanisms Reactions that occur to restore the internal
environment to normal.

Information is relayed to the organ involved
through the nerves or hormones.

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THERMOSTAT in water heater detects
the temperature

Switch on → if temperature too low
Switch off → if temperature too high

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HOMEOSTATIC CONTROL PROCESS

Increases Control Corrective decreases
Centre mechanism

Normal Temperature Normal Temperature
Range Range

Decreases Control Corrective increases
Centre mechanism

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Regulation of Water Content

Increases Detected by Corrective mechanism decreases
the brain Hormone→kidney→

produce more urine

Normal Water Level Normal Water Level

Decreases Detected by Corrective mechanism increases
the brain Hormone→kidney→
produce less urine
9/14/2022 Feel thirsty

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Regulation of Body Temperature

Human body temperature needs to be maintained at 36.5˚C – 37.7˚C

Because most of the enzymes involved in the body’s biochemical
reactions function at optimal levels at this temperature.

System involved :
▪ Excretory system
▪ Endocrine system

Organs that are involved: MRSM TRANSKRIAN SCIENCE UNIT FORM 1 2022
▪ Skin
▪ Brain
▪ Skeletal muscles

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Regulation of Body Temperature

Detected by the Corrective mechanism decreases
brain - Blood vessel dilate
-Hairs lie flat
Increases -Increase sweating
-Hormone/skeletal activity
reduced
-Less urine

Normal Temperature (37oC)

Normal Temperature (37oC) Corrective mechanism increases

- Blood vessel constrict

Decreases - Hairs stand erect Decrease

sweating

Detected - Skeletal muscles will contract and
relax actively = individual shiver

by the - Certain hormones will be

brain secreted
- Body metabolism increase

9/14/2022 MRSM TRANSKRIAN SCIENCE UNIT FORM 1 2022 - More urine

Regulation of Body Temperature

9/14/2022 The condition of skin layer during higher and lower surrounding temperature

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Heartbeat Rate Heart rate is measured by
counting the pulse at the
Heartbeat rate is the
number of heartbeats wrist

within one minute
(60 second)

Heartbeat when carry out vigorous
activities

9/14/2022 MRSM TRANSKRIAN SCIENCE UNIT FORM 1 2022 The heart needs to pump more blood
into the cells of the body to supply
more oxygen

HOMEOSTASIS IN ANIMALS

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HOMEOSTASIS IN ANIMALS

Animals also carry out the
process of homeostasis like

humans

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In a hot environment, cats
lick fur to reduce body
temperature

The heat is released when
the saliva on their fur
evaporates

Cat's fur stand
erect when cold

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COLD SURROUNDING

• Body activity→ slower
• Muscles function more slowly
• Movements become slower
• Metabolism rate decreases
• Body temperature

9/14/2022 HOT SURROUNDING

• Body activity→ faster
• The heart beats faster
• Movements become faster
• Metabolism rate increases
• Body temperature

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• Snail loses water → on skin surface
• Looks for humid places

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• Has waxy skin layer
• Loss water vapour → through spiracles
• Closes spiracles between two breathing

movement to reduce water lose

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HOMEOSTASIS IN Stomata
PLANTS
When temperature too
• Plant carry out homeostasis to high

regulate water content. Stoma closes→ reduce
water evaporated
• Water is very important to During the day
plants for the photosynthesis Stoma opens→ enable
more water to be
and other life processes. evaporated

• Most plants lose water through

transpiration.

• Stomata helps to absorb and

release water and gas during

photosynthesis

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Process which water in
the form of water vapour

from plants are lost to
the surrounding through

the stoma

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HOMEOSTASIS IN PLANTS

Afternoon

(leaves roll up to avoid

excessive water loss) Evening

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IMPORTANCE OF HOMEOSTASIS TO HUMANS AND LIVING THINGS

• Provide optimum conditions • Reactions that are catalyzed by
for cells to carry out the enzymes can happen at an
metabolisms process optimal rate
effectively.

• Regulate water content and
body temperature to prevent
health issues

• Enables an organisms to decrease or
increase its body’s metabolic rate
according to its individual needs.

• Enables organisms to adapt in new habitats MRSM TRANSKRIAN SCIENCE UNIT FORM 1 2022

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