F1 C3 1t2l13

CHAPTER 3:

Coordinati on and response

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 wat temperat Blood ure

er

pH

pressure

Allow living processes in body  work well

mperature too high cells in organism may d

THERMOSTAT in water heater detects the temperature Switch on  if temperature too low Switch off  if temperature too high

ormal Temperature Range Decrea ses

Control centre

Corrective mechanism

Normal Temperature Rang

Corrective mechanism

increas es

Control centre

decrea ses

Increas es

HOMEOSTATIC CONTROL PROCESS

Normal Water Level Decrea ses

Detected by the brain

Corrective mechanism hormonekidney produce more urine

Normal Water Level

Corrective mechanism hormonekidney

increas es

Detected by the brain

decrea ses

Increas es

Regulation of water content

Normal Temperature (37oC) Decrea ses

Detected by the brain

Corrective mechanism -blood vessel dilate -hairs lie flat -Increase sweating -hormone/skeletal activity reduced -less urine

Normal Temperature (37oC

Corrective mechanism -blood vessel constrict -hairs stand erect -Decrease sweating -hormone/skeletal activity will be active

increas es

Detected by the brain

decrea ses

Increas es

Regulation of body temperature

HOMEOSTASIS IN ANIMALS They have no sweat gland. How they maintain homeostasis

Lick fur to reduce body temperatu

cat's fur stand eract

dog hang tongue out to decrease temperature

COLD SURROUNDING • Body activity slower • Body temperature

HOT SURROUNDING • Body activity faster • Body temperature

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

• • •

Has waxy skin layer Loss water vapourthrough spiracles Closes spiracles between 2 breathing

HOMEOSTASIS IN PLANTS

Afternoon (leaves roll up to avoid excessive water loss)

evening

TRANSPIRATION Process which water (in the form of water vapour) from plants are lost to the surrounding through the stoma

During the day Stoma opens enable more water

When temperature too high Stoma closes reduce water

IMPORTANCE OF HOMEOSTASIS TO HUMANS AND LIVING THINGS Provide optimum conditions Maintained in a balanced and stable conditio Without homeostasis: