Sponge (Pg. 36) Hypothesize how these climbers hang on to their body temperature.

Hypothesize how these climbers hang on to their body temperature. His body is working inside to provide energy and to maintain a stable body temperature.

28.2 Mechanisms of Homeostasis Set up Cornell Notes on pg. 37 Topic: 28.2 Mechanisms of Homeostasis Essential Question(s): On the top ½ of pg. 36 please create a double-bubble comparing and contrasting Negative and Positive feedback On the bottom ½ of pg. 36 please draw your own negative feedback loop with a real example NOT used in class 28.2 Mechanisms of Homeostasis 2.1 Atoms, Ions, and Molecules

KEY CONCEPT Homeostasis is the regulation and maintenance of the internal environment.

Homeostasis is the regulation and maintenance of the internal environment within the narrow ranges that support human life. It is a delicate balance. Temperature Fluids Salts pH nutrients

Conditions within the body MUST remain within a narrow range. Homeostasis involves keeping the internal environment within set ranges.

Human Internal Environment Protects our cells from external changes Is relatively constant, despite an ever-changing outside environment (98.6 degrees)

How does a thermostat work? Your control center (brain) is like a thermostat Has a set temperature (98.6) If it is too hot- sends signals to effectors (sweat glands) to lower body temp (ex: sweat) If too cold- sends signals to effectors to raise body temp (ex: shiver) How does a thermostat work? Air conditioner Heater

activated by an imbalance Negative Feedback: The control system (brain) sends signals/instructions to effectors (muscles and glands) to stabilize the body activated by an imbalance corrects an imbalance, brings body back to Homeostasis Pancreas receptors detect high blood sugar Stimulus: rising blood sugar The control center signals the pancreas to secrete insulin Effector: Insulin causes liver cells to take up sugar in the blood Response: blood sugar returns to normal= homeostasis

100* Change occurs in internal or external environment

Receptors Sensors: Gather data, and Send signals to the control center

The brain receives data, and compares it with “set point”, sends messages to effectors

Work to return the body to balanced levels- delivers messages to target organs/glands

Targets respond to change, and body returns to homeostasis

Please complete a negative feedback loop for body temperature rising due to it being 110* outside

Real life example: 100* Body temperature rises above 98.6 due to it being 110* outside

Skin sensory receptors send signals to brain

The hypothalamus detects the difference from the set point: 98. 6 The hypothalamus detects the difference from the set point: 98.6* and signals effectors

Messages sent to sweat glands

You sweat, body temperature lowers to normal (98.6)

How are negative feedback loops necessary for homeostasis? Feedback compares current conditions to set ranges. Negative feedback counteracts change Keeps environment stable Negative Feedback Loop Holding breath, CO2 levels rise, O2 / CO2 level returns to normal Control system forces exhale, inhale

Positive Feedback: Process by which changes cause additional similar changes, producing unstable conditions- pushes away from homeostasis

Positive feedback increases change Important when rapid change is needed platelets fibrin white blood cell red blood cell blood vessel clot EX: Torn vessel stimulates release of clotting factors

At your table, please explain the difference between a negative feedback loop and positive feedback loop? Negative feedback loop counteracts change away from set points. Positive feedback loops increases change away from set points.

Homeostasis is the regulation and maintenance of the internal environment within the narrow ranges that support human life. Body temperature is normal Normal amounts of blood and other bodily fluids With your neighbor, please make a list of external or internal factors that would affect your body’s homeostasis.

Lifestyle (drinking, smoking, diet) Injury Illness (fever, infection) Please make a list of external or internal factors that would affect your body’s homeostasis. Pg. 37 Disease Stress Lifestyle (drinking, smoking, diet) Injury Illness (fever, infection) Dehydration/Starvation Outside temperature

A disruption of homeostasis can be harmful Sensors fail to detect changes Wrong messages sent Messages fail to reach their targets Serious injuries overwhelm the body Viruses or bacteria change the body’s internal chemistry

Short term effects Last a few days or weeks Ex: A cold virus enters your body Within a few days your immune system begins to kill the virus

Long term effects Causes long term damage to the body Ex: diabetes

Homework On the top ½ of pg. 37 draw a double-bubble map, comparing and contrasting negative and positive feedback. Make sure you give examples of each.

Causes additional changes stimuli Corrects an imbalance Causes additional changes stimuli Negative Feedback receptors Positive Feedback Ex: Contractions during childbirth Ex: temperature regulation Control center Moves body away from homeostasis effectors Returns body to homeostasis