1.2 Maintaining Life

Objectives: 1. Become familiar with the human body’s necessary life functions

& survival needs.2. Define homeostasis & how it persists in the body.3. Differentiate between positive & negative feedback and provide

examples

Necessary Life Functions: Maintained boundaries (insides separate

from outside) Movement Responsiveness (to environment) Digestion Metabolism (ATP, energy) Excretion (removing waste) Reproduction Growth (cell growth)

Survival Needs Nutrients (for energy & cell maintenance Oxygen (O2 releases energy from food) Water Regulated body temperature (98.6° F) Regulated atmospheric pressure (for breathing)

Homeostasis The body’s ability to maintain relatively stable

internal conditions even though the outside world is continuously changing

A.K.A. “balance” or “equilibrium” In order for homeostasis to occur/continue,

the following are needed…

Homeostasis needs…

1. A Receptor: A type of sensor that responds to changes in the environment.

2. A Control Center: Analyzes information it receives from the environment then determines the response.

3. The Effector: Acts out the control center’s response to the stimulus.

Feedback

Negative Feedback The most common

feedback The body is trying to

slow or stop the stimulus

Feedback

Positive Feedback Far less common The body is trying

to increase the stimulus Ex. Childbirth &

Blood clotting