1. Announcements Complete Knowledge survey on-line before 9 pm Monday
Lab this week: Frog Reflexes
Review information on lab webpage
Upcoming Quiz (probably Friday): Thermoregulation and Glucose Homeostasis and Frog Reflexes

2. Acclimitization ≠ Adaptation
1st day on the job
Increase body temp….. Delayed sweating via negative feedback
10th day on the job
Sweating precedes changes in core body temperature
and sweating is increased
And salt loss in sweat is minimized
Responses begin even before core temperature increases! Not just negative feedback, this is Feed Forward (requires experience). FF is evidence of Acclimitization.
Acclimitization ≠ Adaptation

3. Acclimatization & Feedforward
Deviations from set point are minimized
Learned (by experience)
Anticipates changes of a physiological parameter
Response begins before there is a change in the physiological variable
Minimizes fluctuations

4. ~37oC
Be able to explain the physiology in each of these situations with a detailed diagram of negative feedback responses!

5. Heat Stroke Blood Pressure Blood Flow to brain Cutaneous vasodilation
Sympathetic outflow
Blood Pressure
Blood Flow to brain
Disrupted function of neurons
Cutaneous vasodilation
Sweating

6. Positive feedback Inherently unstable
Examples of Positive Feedback in Physiology
Heat stroke
formation of blood clot
menstrual cycling of female sex hormone concentrations
generation of action potentials in nerve fibers
uterine contractions during childbirth
Each of these examples terminate naturally (self limiting)
Homeostasis is achieved by negative feedback loops: the integrator detects deviations from set point and orchestrates responses produced by effectors that return the parameter toward the set point.