Life Functions & Homeostasis. Necessary Life Functions 1.Maintain boundaries 2.Movement Locomotion Movement of substances 3.Responsiveness Ability.

Life Functions & Homeostasis

Necessary Life Functions

1. Maintain boundaries

2. Movement

Locomotion

Movement of substances

3. Responsiveness

Ability to sense changes and react

4. Digestion

Break-down and absorption of nutrients

Necessary Life Functions

5. Metabolism—chemical reactions within the body

Produces energy

Makes body structures

6. Excretion

Eliminates waste from metabolic reactions

7. Reproduction

Produces future generation

8. Growth

Increases cell size and number of cells

Survival Needs

1. Nutrients

Chemicals for energy and cell building

Includes carbohydrates, proteins, lipids, vitamins, and minerals

2. Oxygen

Required for chemical reactions

Survival Needs

3. Water

60–80% of body weight

Provides for metabolic reaction

4. Stable body temperature

5. Atmospheric pressure

Must be appropriate

Interrelationships Among Body Systems

Figure 1.3

Homeostasis

Homeostasis—maintenance of a stable internal environment

A dynamic state of equilibrium

Homeostasis is necessary for normal body functioning and to sustain life

Homeostatic imbalance

A disturbance in homeostasis resulting in disease

Homeostasis - Fishbowl Model

Fishbowl Human Body Function

Water

Glass bowl

Fish

Air Pump

Filter

Heater

Feeder

Everything working together Homeostasis!

Bodily Fluids

Skin

Cells

Lungs

Kidneys

Muscles

Digestive System

Internal env’t

Barrier

Maintain life

Keep high O2 level

Remove wastes

Constant temp

High nutrients

Figure 1.4

Changedetectedby receptor

Stimulus:Produceschangein variable

Input:Informationsent alongafferentpathway to

Receptor (sensor) Effector

Variable(in homeostasis)

Response ofeffector feedsback toinfluencemagnitude ofstimulus andreturns variableto homeostasis

Controlcenter

Imbalance

Imbalance

Output:Information sentalong efferentpathway to activate

Figure 1.4, step 1a

Variable(in homeostasis)

Figure 1.4, step 1b

Stimulus:Produceschangein variable

Variable(in homeostasis)

Imbalance

Imbalance

Figure 1.4, step 2

Changedetectedby receptor

Stimulus:Produceschangein variable

Receptor (sensor)

Variable(in homeostasis)

Imbalance

Imbalance

Figure 1.4, step 3

Changedetectedby receptor

Stimulus:Produceschangein variable

Input:Informationsent alongafferentpathway to

Receptor (sensor)

Variable(in homeostasis)

Controlcenter

Imbalance

Imbalance

Figure 1.4, step 4

Changedetectedby receptor

Stimulus:Produceschangein variable

Input:Informationsent alongafferentpathway to

Receptor (sensor) Effector

Variable(in homeostasis)

Output:Information sentalong efferentpathway to activate

Controlcenter

Imbalance

Imbalance

Figure 1.4, step 5

Changedetectedby receptor

Stimulus:Produceschangein variable

Input:Informationsent alongafferentpathway to

Receptor (sensor) Effector

Variable(in homeostasis)

Response ofeffector feedsback toinfluencemagnitude ofstimulus andreturns variableto homeostasis

Output:Information sentalong efferentpathway to activate

Controlcenter

Imbalance

Imbalance

Maintaining Homeostasis

The body communicates through neural and hormonal control systems

Receptor

Responds to changes in the environment (stimuli)

Sends information to control center

Maintaining Homeostasis

Control center

Determines set point

Analyzes information

Determines appropriate response

Effector

Provides a means for response to the stimulus

Feedback Mechanisms

Negative feedback

Includes most homeostatic control mechanisms

Shuts off the original stimulus, or reduces its intensity

Works like a household thermostat

Positive feedback

Increases the original stimulus to push the variable farther

In the body this only occurs in blood clotting and during the birth of a baby

Homeostasis Video

QuickTime™ and a decompressor

are needed to see this picture.