Presentation on theme: "BELLWORK – 2/4/2014 1. Read pages 29-31 in your review book on FEEDBACK and HOMEOSTASIS. 2. Read and discuss QUIETLY the ESSENTIAL question below with."— Presentation transcript:
BELLWORK – 2/4/2014 1. Read pages 29-31 in your review book on FEEDBACK and HOMEOSTASIS. 2. Read and discuss QUIETLY the ESSENTIAL question below with your table partner (be prepared to explain if called upon): During hot weather and vigorous exercise, people sweat. As the water on their skin evaporates, the water molecules absorb heat energy. Explain why this process is important to the individual.
Dynamic Equilibrium Our bodies are constantly responding and adjusting to external and internal stimuli, causes small changes in our body temperature, blood sugar level, etc. We refer to these small changes as dynamic equilibrium. This allows us to maintain homeostasis (internal balance). All living things must maintain homeostasis in order to survive. EX. Human body temp is 37 C; if temp is altered, processes that keep us going will begin to failAll living things must maintain homeostasis in order to survive. EX. Human body temp is 37 C; if temp is altered, processes that keep us going will begin to fail
Dynamic Equilibrium TIME BODY TEMP BLOOD SUGAR LEVEL AFTER MEAL Constant small corrections that keep internal environment w/in stable limit
TYPES OF FEEDBACK MECHANISM 1. Negative Feedback shut off considered negative because the original signal is lowered or shut off. Stimulus ReactionResponse Negative Feedback
Examples OF FEEDBACK MECHANISM Ex. Body Temperature EX: Thermostat ROOM COOLS DOWN FURNACE KICKS ON ROOM WARMS UP FURNACE KICKS OFF Stimulus: Brain senses a drop in blood temperature. Reaction: Nerve message sent to muscles to start shivering. Response: Heat is generated that warms the body and blood. Negative Feedback: Warmer blood triggers brain to turn-off shivering.
Example 3: Glucose levels in the blood Blood sugar regulation by insulin (secreted by pancreas) Video: Insulin, Glucose and you http://www.youtube.com/watch?v=ae_jC4FDO Uc http://bcs.whfreeman.com/thelifewire/conten t/chp50/5002s.swf
Ex 4. Plants regulating water loss Guard cells in plants opening and closing to prevent water loss
2. Positive Feedback Mechanism – Change in system causes greater change or response Stimulus: A contraction pushes the babys head against the base of the uterus. Reaction: Pressure on the base of the uterus causes stronger contractions. Response: Baby is born and the feedback cycle ends. Positive Feedback