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Introduction: Harsh Reality TV

PART I  Principles of Homeostasis

Homeostatic Systems Share Several Key Features

Negative feedback allows precise control

Redundancy ensures critical needs are met

Animals use behavioral compensation to adjust to environmental changes

PART II  Fluid Regulation

Water Moves between Two Major Body Compartments

Two Internal Cues Trigger Thirst

Osmotic thirst occurs when the extracellular fluid becomes too salty

Hypovolemic thirst is triggered by a loss of fluid volume

We don’t stop drinking just because the throat and mouth are wet

PART III  Food and Energy Regulation

Nutrient Regulation Helps Prepare for Future Needs

Insulin is essential for obtaining, storing, and using food energy

The Hypothalamus Coordinates Multiple Systems That Control Hunger

RESEARCHERS AT WORK: Lesion studies showed that the hypothalamus is crucial for appetite

Hormones from the body drive a hypothalamic appetite controller

Other systems also play a role in hunger and satiety

Obesity Is Difficult to Treat

Eating Disorders Can Be Life-Threatening

SIGNS & SYMPTOMS: Friends with Benefits