BIOL 1082 Lecture Notes - Lecture 29: Poikilotherm, Blubber, Negative Feedback
Ch. 42- LO
Homeostasis and temperature regulation Textbook Reading: Sections 42.7-42.8
1. Define homeostasis, and explain how feedback control is used to maintain it.
• Homeostasis moderates but doesn't eliminate changes in the internal environment.
• Homeostasis- tendency toward a relatively stable equilibrium between elements
• It's an interplay between external factors that tend to change the internal environment
and internal control mechanisms that oppose these changes
• Feedback control:
o Homeostasis in animals relies on negative feedback. Negative feedback is a
control mechanism that reduces or damps the stimulus.
▪ For example: when you exercise, you produce heat which increases body
temperature. Your nervous system detects this increase and triggers
sweating. The sweat helps your body to return your body temperature to
its set point and eliminating the stimulus.
2. Define how organisms can be categorized with respect to temperature regulation.
• An organism to keep its body temperature within certain boundaries even when the
surrounding temperature is very different, this ability to regulate body temperature
known as thermoregulation. On the basis of temperature regulation animals can be
divided into three categories:
o Homeotherms: Humans are homeotherms. Those animals who maintain
a constant internal body temperature across a wide range of environmental
conditions. Another advantage of a homoeothermic animal is its ability to
maintain its constant body temperature even in cold weather.
o Poikilotherms: Animals whose temperature changes according to the
environmental temperature. Poikilotherms at the same trophic level often have
much shorter generations than homeotherms: weeks rather than years. This
difference in energy requirement also means that a given food source can
support a greater density of poikilothermic animals than homoeothermic
animals. Examples snakes.
o Heterotherms: Animals which usually keep a constant body temperature, but
have specific periods where their temperature is different, such as during
hibernation. Ground squirrels are heterotherms.
3. Describe the mechanisms of heat transfer relevant to animals.
• Isulatio: redues the flo of heat etee aial’s ody ad its eiroet.
Insulation can include hair or feather or layers of fat or blubber.
• Conduction-heat transfer through molecule motions
• Radiation-transfer via electromagnetic waves
• Convection- transfer through mass movement of substance
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