Transcript Physiological (function) adaptations for survival

Physiological (function)
adaptations for survival
Physiological adaptations

An animal’s physical ability to deal with
its environment determines whether it
is able to survive there
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Nervous system and reflexes
Hormonal
Regulation of water balance and temperature
Water balance in small desert
animals
Metabolic water
available for
use in mouse
Tarrkawarra (Spinifex mouse)
Very little
water
content in
urine
Water in food –
depends on
food source
Free water
(dew/rain) may
be very little or
none
Very little
water in
faeces
WATER IN
WATER OUT
Some
evaporation
from skin –
minimised by
huddling in
burrows
Loss in exhaled air
Homeostasis

Homeostasis is a body keeping the
INTERNAL environment constantly
within a tolerable range, despite
EXTERNAL environmental changes.
Tolerance levels in humans
Ions (e.g Ca2+ in
plasma) – 2.3 – 2.4
mmol per L
Blood pressure –
relaxed: 13.3 kPa.
Contracted: 5.33
kPa.
Blood glucose –
3.6 – 6.8 mmol
per L
Temperature: 36.1 –
37.8 degrees Celsius
Water – intake must
balance loss
pH of arterial blood – 7.4
(for enzyme action)
Urea in plasma <7mmol per L
Other organisms have
tolerance levels too!

Plants must regulate water balance
and concentration of gases such as
carbon dioxide and oxygen
Systems contribute to
homeostasis

Body systems help to regulate critical
tolerance levels
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Endocrine system – hormones
Nervous system
Behaviours can assist in homeostasis too
(eg. Getting a thicker blanket on a cold night,
drinking water habitually with meals)
Questions etc
pg 301 Quick Questions
Glossary words: homeostasis, tolerance
range, limiting factor
Keeping it all the same

The nervous system and the endocrine
system work together to perform
homeostasis

Nervous system detects change
Endocrine system responds to change

The Nervous System
The response system
Detection of
change by
affector neurons
Change
message
decoded
in CNS
Effector neurons
send response
message back to
area of change