1. Getting and Using Nutrients
Feedback Mechanisms
A cycle of events in which information from one step controls or affects a previous step.
Homeostasis-the maintenance of a stable internal environment in the body
Getting and Using Nutrients
Glucose is the primary food source

2. Getting and Using Nutrients
Glucose is the primary food source
Blood-glucose feedback mechanism
Glucose molecules cannot enter most cells by osmosis
Transport proteins-help move glucose molecules through the cell membrane
See Figure 2 on Page 541

3. Maintaining Homeostasis
Nervous System-senses internal and external environments
Uses electrical impulses and chemical messengers to respond to senses
Nervous System Feedback
Nerves carry responses to environmental conditions
Carried by electrical impulses and neurotransmitters

4. Endocrine System
Endocrine System-collection of glands and groups of cells that produce chemical messengers called hormones
Regulate many of the body’s important functions
The body’s water level