AIM: What strategies do organisms use to maintain homeostasis? November 24, 2014 AIM: What strategies do organisms use to maintain homeostasis? Do Now: How do we keep the inside of our homes at a stable temperature, even when it is hot or cold outside? BE SPECIFIC! Take out homework

Homeostasis Homeostasis = stability and balance inside of our bodies, even when our outside environment is unstable, and changes a lot Example: Temperature Homeostasis How do we do this in our homes?

Temperature “Homeostasis” in our Homes Set point = the desired, stable room temperature When the room temperature is at the set point, HOMEOSTASIS has been reached. How do we do this in our bodies?

Temperature “Homeostasis” in our Bodies Our bodies maintain homeostasis using NEGATIVE FEEDBACK. Negative feedback is the body’s REACTION to an external change. It is “negative” because it OPPOSES (goes against, or opposite) the external change.

Temperature “Homeostasis” in our Bodies Normal body temperature: 98.6F It’s hot outside! It’s cold outside! Negative Feedback Loop: Body begins to heat up Body cools back down Body begins to cool Body heats back up Brain detects higher temperatures and sends signal to sweat glands Brain detects lower temperatures and sends signal to muscles Sweat glands release sweat Muscles shiver

Types of Homeostasis: Temperature homeostasis Nutrient homeostasis Blood oxygen level homeostasis - exercise Water level homeostasis the kidneys! Blood sugar level homeostasis - diabetes

Body Systems work to maintain Homeostasis

Article: Prader-Willi Syndrome How does Prader-Willi syndrome affect homeostasis? Discussion Questions What is the body’s normal response to eating? How is this an example of negative feedback? What is wrong with Prader-Willi patients?

Eating and Negative Feedback What could be wrong with Prader-Willi patients? Normal stomach fullness and nutrient levels You haven’t eaten in awhile Stomach is empty Stomach is full The brain stimulates feelings of hunger, causing us to eat. Stomach cells detect the lack of food, and send chemical signal (ghrelin) to the brain.

EXIT TICKET Relate this image on how our bodies maintain homeostasis (BALANCE).

2 - Hypertension

Which body system is malfunctioning? 1 2 3 4 5 6 7 8 9

3) Asthma

Which body system is malfunctioning? 1 2 3 4 5 6 7 8 9

4) Diabetes

Which body system is malfunctioning? 1 2 3 4 5 6 7 8 9

5) Lactose Intolerance

Which body system is malfunctioning? 1 2 3 4 5 6 7 8 9

6) Kidney Stones

Which body system is malfunctioning? 1 2 3 4 5 6 7 8 9

Scientific Synthesis Describe how our bodies use negative feedback to maintain homeostasis. In your answer, be sure to include: the definition of homeostasis the different levels of organization of the human body that work to maintain homeostasis the definition of negative feedback, and how negative feedback helps to maintain homeostasis one example of negative feedback, including the identification of a body system responsible for this particular type of feedback what happens when our bodies cannot properly maintain homeostasis, including one specific example