TEMPERATURE AND
HOMEOSTASIS
Group B
Shaunna, Stephanie, Nikki & Jo
What is Homeostasis?

HOMEOSTASIS
– noun
the tendency of a system, the physiological
system of higher animals, to maintain internal
stability, owing to the coordinated response of its
parts to any situation or stimulus tending to
disturb its normal condition or function.

The constant maintenance of your internal
environment.

Homeostasis is the overall system linked to
many other systems that regulates our core
temperature.
Homeo = same
Stasis = position
The Greatest Balancing Act
of all time
 The only consistent thing in our life is
change.
 Homeostasis is responsible for maintaining
our body at its optimum functioning level
by responding to these constant changes –
so without it we would die.
 Every time our body senses that we are
“out of balance” with our regular
temperature (37˚C) it will try and regain
stability – like a pair of scales that is almost
always balanced.
The negative feedback system
and temperature regulation
 A negative feedback system is a mechanism that a homoeotherm
(warm blooded animal) uses to protect itself from the ever changing
weather conditions of their environment no matter the temperature,
for example a humans core body temperature should be at a constant
37 degrees C and these negative feedback mechanisms is what
regulates this temperature which is our case is especially critical for
our existence as this core temperature can only safely range two
degrees without causing either hyperthermia or hypothermia, It is
important to maintain a constant temperature so that living
organisms can maintain healthy and regular operation.
The negative feedback system
and temperature regulation
Temperature in mammals is detected by thermoreceptors in the skin and
hypothalymus which is in the brain. Changes in temperature bring about nerve
impulses from the brain to the muscles and glands which will bring about changes
depending on whether it is hot or cold.
Control center
— where the messages are received from the receptors about change in the body's
temperature then sending messages to effectors to change their function to correct the
recognized change
Effector
— the muscle or organ that receives messages from the control center to change its function
in order to correct the change of the body's internal conditions.
Hormone
— chemical the body produces to alter function or messages being sent
Receptor
— A structure that monitors the body's internal functions and conditions; detects changes in
the body's internal environment, in this case is temperature.
Set point
— The range of normal functional values of an organ or structure which for a human body
would be set at 37 degrees.
Why do we shiver?
We shiver in a response to low temperature, muscles contract &
relax repeatedly, thus generating heat by friction & from
metabolic reactions. When our core body temperature falls, the
shivering reflex is triggered. Shivering is triggered in an attempt
to avoid hypothermia, when our body temperature is lowered to
dangerous levels, our muscles are encouraged to contract &
expand quickly, thus resulting in a shiver. This causes more heat in
the skeletal muscles to be produced to provide additional warmth
to vital organs.
Interesting fact:
Whales do not shiver.
They have an effective thermo regulatory
system, which keeps their body temperature
still; whether they are in warm, tropic waters or
icy Arctic waters. Whales have a thick layer of
blubber, (that can be up to 20 inches thick), this
protects the whales from extreme
temperatures.
Piloerection- not just a
funny name
Erection of the hair of the skin.
E.g. Piloerection of the hair on the arm
causes it to "stand on end."
It is begun when a stimulus (drop in
temperature/a fright) causes a release
from the (involuntary) nervous system
which triggers tightening of muscles.
The contractions which are triggered, raise the hair follicles
& trap an insulating layer of still, warm air next to the skin.
Sweating – a horrible stench
or vital mechanism?
Sweating is a negative
feedback response when
our core temperature rises
over 37˚C
• The hypothalamus senses
that the body is too hot via
neuron impulse.
• Sweat glands underneath
your skin activate releasing
sweat
•Sweat evaporates off
•Ending with cool sensation
Negative Feedback Response
Hypothermia – how does it
happen?
Core body temperature drops to
35˚C or below.
Body tries to stay warm. (shivering)
Body stops shivering to conserve
energy. Blood just starts being
pumped to vital organs.
Blood doesn’t go to parts of the
body that it doesn’t classify as
‘important’ (fingers, toes) and
they eventually die. This is called
Frostbite.
Hypothermia – Symptoms
 Feeling cold
 Shivering
 Loss of control of fine motor muscles (fingers etc)
 Feeling lethargic (very tired)
 Difficulty breathing
 Shivering stops
 Breathing slows down
 Coma
 Death
The nervous system and
temperature regulation
-The command
centre of the
nervous system is
the brain
- The part of the
brain that controls
homeostasis is
- When receptors (e.g. skin receptors)
called the
sense a change or deviation they send a
hypothalamus
message to the hypothalamus , which
then sends chemical and electrical
messages to that part of the body to
re-establish normality.
What you should have learned
by now – key terms

Homeostasis is the constant maintenance of the internal environment.

In temperature regulation, the skin receptors pick up change in the temperature in
the external environment, the hypothalamus detects the change and then responds
with a negative feedback mechanism (e.g. shivering, sweating) to ensure the body
returns to its norm.

Sweating – Is a negative feedback response and occurs when the hypothalamus
senses the body is too hot.

Hypothermia – Also a negative feedback response but is life threatening as the body
loses more heat then it can generate allowing core body temperature to drop below
35˚C.

Shivering - is initiated due to a drop in temperature, it causes muscles to contract
and relax frequently. It is triggered in an attempt to avoid hypothermia, our skeletal
muscles produce extra heat for our organs.

Piloerection - Is erection of the hair. Stimulus triggers contractions of muscles. The
contractions cause hair follicles to rise, and trap a warm, still layer of insulating air
next to the skin. “Hairs stand on end.”
Bibliography

http://pespmc1.vub.ac.be/HOMEOSTA.html
http://upload.wikimedia.org/wikipedia/commons/f/f1/2003-09-17_Goose_bumps.jpg

http://fog.ccsf.cc.ca.us/~mmalacho/physio/oll/Lesson1/hstasis.html
http://dictionary.reference.com/browse/homeostasis

http://farm4.static.flickr.com/3173/3029642097_33c42e073e.jpg
http://www.biology-online.org/4/4_temperature_regulation.htm

World of teaching. "What mechanisms are there to cool the body down?" Web. 24 July 2009.

Better Health Channel. "Hypothermia." Web. 24 July 2009.

Yahoo Answers. "Why does sweat smell? Why do we sweat from our armpits?" Web. 28 July 2009.

http://www.biology-online.org/4/4_temperature_regulation.htm

http://science.jrank.org/pages/3365/Homeostasis.html#ixzz0MWUz8dBb