Download Introduction to Homeostasis

Introduction to
A Cooling Glove The heat extractor increases heat loss and allows
the body to perform at a higher level in severe conditions.
Core Temperature
• Humans have a normal temperature
of around 36.2 to 37.2 degrees
Celsius
– Above (hyperthermia): infection
– Below (hypothermia): cell death
http://news.bbc.co.uk/2/shared/spl/hi/health/03/travel
_health/diseases/html/sars.stm
http://asimplebutimpossibletask.blogspot.com/
What is Homeostasis?
• The body’s attempt to
maintain “normal” levels
within your body, despite
environmental differences
http://balancewines.wordpress.com/2009/12/
• dynamic equilibrium- a
mechanism to ensure that
all body systems function
within an acceptable
range to sustain life
Organization of a Human
cells  tissues  organs  organ systems
Homeostatic control systems
• 3 components:
– Monitor(receptors)
– Coordinating centre(brain)
Monitor
Change in
balance
Coordinating
centre
– Regulator(muscles, glands
etc.)
• Monitors send signals to the
coordinating centre that the
normal levels have changed
(sensory pathway).
• The coordinating centre then
messages the regulator which
helps restore normal balance
(motor pathway).
Normal
balance
Regulator
Homeostasis
Example: household thermostat
• Room T at 22 oC
– T below: thermostat turns on the
furnace
– T above: thermostat turns off the
furnace
http://gasfurnaceprices.co.cc/
Example: household thermostat
MonitorThermometer
Detects decrease in
temperature
Furnace turns off
Thermostat detects temperature
increases over “normal”
Coordinating centre- Thermostat
switches on furnace
Regulator- Furnace
Whole control system is called a negative
feedback system
Negative feedback
• Process by which a mechanism is activated to restore
conditions to their original state
• It ensures that small changes don’t become too large.
– Why is a thermostat a negative feedback system?
Negative Feedback
Example: Thermoregulation of body
• The maintenance of body
temperature within a range that
enables cells to function efficiently
–Heat Stress
–Cold Stress
Heat stress
• Thermoreceptors (PNS)
detect an increase in body
temperature
• Hypothalamus (CNS) signals
to the sweat glands to
initiate sweating.
• Evaporation of the sweat off
the skin causes cooling.
http://flairforthedramatic.mlblogs.com/archives/2008/09/of_all_times_to_start_w
inning.html
Heat Stress
• The hypothalamus also sends message
to blood vessels in the skin causing
them to dilate.
• Dilation allows for more blood flow to
the skin.
http://www.pgbeautygroomingscience.com/functionsof-the-dermis.html
• Heat from the blood is lost to the skin so
blood can return to core of your body &
cool the internal organs.
Heat Stress
• Monitor: thermoreceptors
• Coordinating centre: hypothalamus turns on
cooling system
• Regulator: skin blood vessels dilate and sweat
glands initiate sweating
• Result: body temperature decreases;
hypothalamus turns off cooling system
Cold stress
• Thermoreceptors message the
hypothalamus
• Hypothalamus sends a message via
the nerves:
– Arterioles of the skin constrict therefore
limiting blood flow =reduced heat loss from
the skin and retains heat in the body.
o Smooth muscle contract that surrounds the
hair follicles in your skin causing the hair to
“stand on end” trapping warm air.
o Skeletal muscle to contract causing
shivering and increasing your metabolism
to make heat.
http://www.clarian.org/ADAM/doc/HealthIllustratedE
ncyclopedia/2/19194.htm
Cold stress
• Monitor: Thermoreceptors
• Coordinating centre: Hypothalamus
• Regulator: skin blood vessels constrict and
skeletal muscles contract
• Result: body temperature increases and
hypothalamus turns off.