HOMEOSTASIS
UNIT 4
What happens in your body when you
do a Triathalon?
• Cell Resp increases
• Body Temp increases to 39 degrees Celsius (due to heat from
CR rxns)
• Sweat is produced to dissipate heat
• This loss of water, drops blood pressure
• Heart responds, Kidneys conserve water
• Electrolytes (salts) are lost in sweat
• Body must use hormones to keep a steady supply of glucose to
CR pathways
• Nervous systems monitors o2 levels, increasing breathing rate
if necessary
• Nervous systems also work with the circulatory system to
divert blood to essential areas (muscles, brain, heart…away
from stomach etc)
4km swim, 180km bike, 42km run!
The “Ideal Body State”
•
•
•
•
•
37 degrees
0.1% blood sugar
Blood pH 7.35
Environment doesn’t always allow for this!
Organs and body systems are constantly
adapting
• See page 324
Homeostasis
All of our organ systems work
together to maintain Homeostasis
Homeostasis is a steady internal
state, keeps conditions in the body
constant.
Examples:
1.
Blood Pressure (circulatory system)
2.
Respiration Rate (respiratory
system)
3.
Body Temperature (circulatory
system)
4.
Blood Sugar (digestive and
circulatory)
The brain and the adrenal system
(hormones) do most of the
regulating.
Three Components of Control
1. Monitors
▫
(Brain stem receptors detect increased CO2 in
the blood)
2. Coordinating Centre
▫
(Nerve cells in brain receive and send a signal to
the diapragm)
3. Regulator
▫
(Diagragm increases depth and rate of
breathing)
Dynamic Equilibrium
• There will always be fluctuations in levels
• Homeostatic mechanisms ensure that all body
systems function within an acceptable range.
• Mammalian Diving Reflex (P. 340)
• Check out the ICEMAN!
• http://www.youtube.com/watch?v=madoDvtKE
es
• Homework…Read P335-336 (Feedback)
• Do Q 1-5 P. 337
• Read P338-341 – Thermoregulation!
Feedback Mechanisms
• Negative – Prevent small changes from
becoming too large (i.e. A thermostat)
• Most controls in the body are negative feedback
• Positive – amplify small effects (i.e. Oxytocin
and childbirth)
Thermoregulation
• Maintenance of body temperature within a range
that enables cells to function efficiently
• Hypothalamus – Region of the vertebrate’s
brain responsible for coordinating many nerve
and hormone functions.
Ecto Vs. Endo
• Ectotherms – Invertebrates, fish, amphibians,
reptiles...Depend on air temp to regulate body
temp.
• Endotherms – Mammals – Are able to maintain
a constant body temp regardless of
surroundings.
Thermoregulation
Stimulus
Physiological
Response
Adjustment
Decreased Enviro Temp
-Constriction of blood
vessels
-Hairs stand on end
-Shivering
Increased Enviro Temp
-Dilation of blood vessels -Heat is dissipated
of skin
-Sweating
http://www.youtube.com/watch?v=eJEXdW
HKDmg
http://www.youtube.com/watch?v=Yotp6ov
9-w0&feature=fvw
-Heat is conserved
-More heat is generated
by increased metabolism
http://www.youtube.com/watch?v=vc86u0Is
Owc&feature=related