Take out your Lab sheets from yesterday You will have 10 minutes to Begin Immediately! Take out your Lab sheets from yesterday You will have 10 minutes to Graph your data Answer the analysis questions You’ll be graded on completion We need to move quickly today (pep rally schedule = 30 minute classes) Last day to complete test analysis is Today Notecards are due Tuesday, March 7th (word, definition, picture in color)

Question Check…

Set up journals Page:____ Title: Feedback Loops EQ: What are feedback loops and how do they help a body maintain homeostasis?

Standard B.10A - describe the interactions that occur among systems that perform the functions of regulation, nutrient absorption, reproduction, and defense from injury or illness in animals

Talk to your shoulder partner: What are some things that your body regulates? (regulate = control)

What is homeostasis? …its all about BALANCE

What does it mean? Maintaining a constant internal environment. Homeostasis comes from the Greek and means “staying the same” Maintaining a constant internal environment. Claude Bernard (1813-1878)

What happens when there is an imbalance in the internal environment?

What other ways did your body respond? Think back to the lab from yesterday. How was your breathing? Start Timer 60 Seconds 60 45 What other ways did your body respond? 30 15

FEEDBACK LOOP: Feedback:  a response within a system (molecule, cell, organism, or population) that influences the continued activity or productivity of that system Loop: a programmed sequence of instructions that is repeated until a particular condition is satisfied How does the idea of a feedback loop relate to the lab from yesterday. What was the stimulus? Response?

The system responds in the opposite direction to the stimulus Negative feedback The system responds in the opposite direction to the stimulus The OPPOSITE thing is added to return to the original condition examples: shivering when you’re cold, blood sugar regulation *As a general rule, most body responses are the result of negative feedback loops

The system responds in the same direction as the stimulus Positive feedback The system responds in the same direction as the stimulus The SAME thing is added to return to the original condition examples: contractions before child birth, blood clotting *there are very few examples of these in body systems.

Is this a positive or negative feedback loop?

Body takes action Normal Normal Body takes action Increase Decrease

Why do we need to maintain a constant temperature? Enzymes work best at normal body temperature (approx. 37oC) Too hot and we can get hyperthermia (40oC). Too cold and we can get hypothermia (35oC).

Taking off some clothes Too hot Skin goes red Sweating Normal Stamp feet Goosebumps Too cold Shivering

Cells need a healthy diet of glucose. Food for the cells… Glucose. Cells need a healthy diet of glucose. Not too much…not too little Body needs to control level of sugar (glucose) in the blood. This is done by the pancreas.

Insulin tells liver to store the glucose as glycogen. Too much glucose… Pancreas secretes a hormone called insulin. Insulin tells liver to store the glucose as glycogen.

Not enough glucose… Pancreas can also secrete a hormone called glucagon. This tells the liver to convert glycogen back to glucose.

Makes insulin. Pancreas Blood Liver Normal blood glucose levels Transports insulin around the body. Converts glucose to glycogen and stores it. Normal blood glucose levels Pancreas Blood Liver Makes glucagon. Transports glucagon around the body. Converts glycogen back into glucose and puts it back into the blood

Diabetes. With diabetes (type I) the pancreas does NOT produce insulin. It used to be called the wasting disease as you died very slowly, becoming weaker and weaker, until you entered a coma.

Blood glucose regulation Temperature regulation Positive or negative? Blood glucose regulation Temperature regulation

For the rest of today… Draw a feedback loop of your own! Requirements: Think about how your body responds when: you get dehydrated you get scared you cut your finger you get tired Use your own example for extra credit. You MUST get approval before you begin. Requirements: Your feedback loop must be titled You must have at least 4 steps in your loop You must write the steps and draw them (they should be colored, too!) These will go up in the hallway…so make them school appropriate and neat! This is for a daily grade.