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Formative Assessment28.2

+1. A system to maintain homeostasis must have at least 4 parts that function together. Name these and parts and briefly explain what each one does. Senors – gather information Control centers – analyze & compares the information

to the desired values Communication systems – send messages from the

control center to regulate the change Targets – receive & respond to the messages

+2. What is the main difference between the way negative feedback and positive feedback mechanisms regulate changes in the body? Negative feedback loops counteract change to return

to a set point. Positive feedback loops accelerate change away from a

set point

+3. When a newborn baby nurses, the mother’s body is stimulated to produce milk. What would happen to the mil supply if the mother chose to bottle feed rather than breast feed? Why? Nursing a baby creates a positive feedback loop

causing the mother’s body to lactate. Bottle feeding eliminates the stimulus.

+4. Suppose you go on a long hike in hot weather. Describe a possible negative feedback loop that would keep your body from overheating. Sensors detect rise in body temperature Increase in blood flow to skin (vasodilation) Sweat glands activated to cause sweating Increase in heart & breathing rates

+5. Reptiles regulate their body temperature by changing their environment. A snake, for instance, must lie in sunlight to warm its body. Mammals, on the other hand, can regulate their internal environment to gain or lose heat. How might this ability give mammals an advantage over reptiles? Mammals can live in a wider range of habitats &

tolerate rapid changes in external conditions