HOMEOSTASIS

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HOMEOSTASIS

• UNIT 4

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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, heartaway from stomach etc)

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4km swim, 180km bike, 42km run!
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The Ideal Body State

• 37 degrees
• 0.1 blood sugar
• Blood pH 7.35
• Environment doesnt always allow for this!
• Organs and body systems are constantly adapting
• See page 324

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Homeostasis

• All of our organ systems work
• together to maintain Homeostasis
• Homeostasis is a steady internal
• state, keeps conditions in the body
• constant.
• Examples
• Blood Pressure (circulatory system)
• Respiration Rate (respiratory system)
• Body Temperature (circulatory system)
• Blood Sugar (digestive and circulatory)
• The brain and the adrenal system
• (hormones) do most of the
• regulating.

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Three Components of Control

• Monitors
• (Brain stem receptors detect increased CO2 in the
  blood)
• Coordinating Centre
• (Nerve cells in brain receive and send a signal
  to the diapragm)
• Regulator
• (Diagragm increases depth and rate of breathing)

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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?vmadoDvtKEes
• HomeworkRead P335-336 (Feedback)
• Do Q 1-5 P. 337
• Read P338-341 Thermoregulation!

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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)

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Thermoregulation

• Maintenance of body temperature within a range
  that enables cells to function efficiently
• Hypothalamus Region of the vertebrates brain
  responsible for coordinating many nerve and
  hormone functions.

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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.

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Thermoregulation
Stimulus Physiological Response Adjustment
Decreased Enviro Temp -Constriction of blood vessels -Hairs stand on end -Shivering -Heat is conserved -More heat is generated by increased metabolism
Increased Enviro Temp -Dilation of blood vessels of skin -Sweating -Heat is dissipated
http//www.youtube.com/watch?veJEXdWHKDmg
http//www.youtube.com/watch?vvc86u0IsOwcfeature
related
http//www.youtube.com/watch?vYotp6ov9-w0feature
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