WELCOME BACK! IN Activity: “Bacteria Inside My Gut” Read & Answer questions Get a Netbook & Log-In Go to www.dwhitebio.weebly.com Open the PPT Notes: Negative Feedback Mech’s Pick-Up & Complete the Notes Handout

Notes: Internal Feedback Mechanisms TEKS 11A Describe the role of internal feedback mechanisms in the maintainance of homeostasis

“IN” QUESTION – Copy & Answer in ISN Animal Systems: Internal Feedback Mechanism’s Describe how your body knows to keep its temperature from getting too high. HINT…Think about which systems interact and what they’re doing!

How did your answer compare? 1. Your nervous system detects a change in temperature 2. Your brain sends signals to your skin (integumentary) and sweat glands (endocrine) to start the production of sweat 3. The evaporation of sweat cools your body 4. Your nervous system detects the cooling temperature and signals to stop sweat production

Homeostasis The ability of cells and organisms to maintain stable internal conditions. Homeo = “constant” Stasis = “stable” There is a range of acceptable conditions Failure to maintain homeostasis can result in illness or death

Like a speaker… The body responds to the change until it returns to “NORMAL”

Endocrine System - Pancreas The pancreas is responsible for the production of insulin (which tells cells to absorb glucose from blood) and glucagon (which tells cells to release glucose into the blood) Insulin and glucagon are both HORMONES.

Endocrine System—Controls When would you expect to find HIGH levels of insulin in a person’s blood? _______________________________________ _________________________________________________ _______________________________________________ ____________ When would you expect to find HIGH levels of glucagon in a person’s blood? _______________________________________ What causes Diabetes Mellitus? (See p.1007)

Endocrine System—Controls KEY When would you expect to find HIGH levels of insulin in a person’s blood? You should expect high levels of insulin in blood when blood glucose levels are HIGH. When would you expect to find HIGH levels of glucagon in a person’s blood? Glucagon can be broken down into glucose, so when it is released into the blood, blood glucose levels must be LOW. What causes Diabetes Mellitus? (See p.1007) Diabetes can be caused when a person’s pancreas is no longer functioning (Type 1 Diabetes) or when their cells no longer respond to insulin (Type 2 Diabetes).

Positive Feedback Positive feedback occurs when the body senses a change and responds by increasing or speeding up the change. Examples: Oxytocin in childbirth (Hormone that increases contractions) Pepsin in digestion (Enzyme that speeds up digestion of proteins) Like a speaker… The body responds to the change by “INCREASING” the change until the event ends to bring the body to normal http://www.biologyreference.com/Ho-La/Homeostasis.html

“OUT” QUESTION – EXIT TICKET Animal Systems: Interactions & Feedback Mechanisms Explain how the Endocrine and Nervous systems interact to maintain homeostasis.

Lab 2: Animal System Interactions TEKS 10A 5 Station Rotations … DUE TODAY

Quiz: Animal System Interactions TEKS 10A, 11A, 11C 10 Questions in 10 min… DUE TODAY

Why is failure of a feedback mechanism “loop” deadly to an organism? EXIT TICKET: Why is failure of a feedback mechanism “loop” deadly to an organism? (Copy & Answer on the BACK of the notes page)