1. Requirements for Life & Homeostasis

2. What do you think? In the space provided on your paper:
Make a list of the requirements for something to be considered living.
Share your list with a partner. Add what they have that you didn’t to your list. Star the new additions to your list.

3. Create a new life form
Before we review the requirements for life, create a new life form with a group
What will it need to be considered living?
What will it need to stay alive?
Draw a picture of your life form and its requirements for life on a white board

4. Necessary Life Functions
What is needed in order to SEE something (think of a ghost)
_______??___________
_______??_____________
Locomotion
Movement of substances
___________??____________
Ability to sense changes and react
__________???_____________
Breakdown and absorption of nutrients

5. Necessary Life Functions
What is needed in order to SEE something (think of a ghost)
Maintain boundaries
Movement
Locomotion
Movement of substances
Responsiveness
Ability to sense changes and react
Digestion
Breakdown and absorption of nutrients

6. Necessary Life Functions
_______??____ - Chemical ??? That take place (where)___
Break down complex molecules into smaller ones
Build larger molecules from smaller ones
Produces energy
Regulated by hormones
_____????_________
Eliminates waste from metabolic reactions
Wastes may be removed in urine or feces

7. Necessary Life Functions
Metabolism—chemical reactions within the body
Break down complex molecules into smaller ones
Build larger molecules from smaller ones
Produces energy
Regulated by hormones
Excretion
Eliminates waste from metabolic reactions
Wastes may be removed in urine or feces

8. Necessary Life Functions
______???____________
Occurs on cellular level or organismal level
Produces future generation
______??____________
Increases cell size and number of cells

9. Necessary Life Functions
Reproduction
Occurs on cellular level or organismal level
Produces future generation
Growth
Increases cell size and number of cells

10. Survival Needs
______??_______ (what label appears on every package of food)
Chemicals for energy and cell building
Includes carbohydrates, proteins, lipids, vitamins, and minerals
____???______ (Think what do you need for cellular respiration)
Required for chemical reactions

11. Survival Needs Nutrients Oxygen Chemicals for energy and cell building
Includes carbohydrates, proteins, lipids, vitamins, and minerals
Oxygen
Required for chemical reactions

12. Survival Needs ____???_____ Stable body ____???_____
60 to 80 percent of body weight
Most abundant chemical in the human body
Provides for metabolic reaction
Stable body ____???_____
37°C (98°F)
____NO Way you know this one!! 
Must be appropriate for gas exchange

13. Survival Needs Water Stable body temperature Atmospheric pressure
60 to 80 percent of body weight
Most abundant chemical in the human body
Provides for metabolic reaction
Stable body temperature
37°C (98°F)
Atmospheric pressure
Must be appropriate for gas exchange

14. Digestive system Takes in nutrients, breaks them down, and eliminates unabsorbed matter (feces)
Respiratory system Takes in oxygen and eliminates carbon dioxide
Food O2
CO2
Cardiovascular system
Via the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs
Blood
CO2 O2
Heart
Urinary system Eliminates nitrogen-containing wastes and excess ions
Nutrients
Interstitial fluid
Nutrients and wastes pass between blood and cells via the interstitial fluid
Integumentary system Protects the body as a whole from the external environment
Feces
Urine
Figure 1.3

15. Homeostasis Homeostasis—maintenance of a stable internal environment
A dynamic state of equilibrium
Necessary for normal body functioning and to sustain life
Homeostatic imbalance
A disturbance in homeostasis resulting in disease

16. Input: Information sent along afferent pathway to control center.3
Output: Information sent along efferent pathway to effector. 4
Control
Center
Afferent
pathway
Efferent
pathway
Receptor
Effector
Receptor detects change. 2
Response
of effector feeds
back to reduce
the effect of
stimulus and
returns variable
to homeostatic level. 5
Stimulus
produces
change in
variable.
IMBALANCE 1
VARIABLE (in homeostasis)
IMBALANCE
Figure 1.4

17. IMBALANCE IMBALANCE Stimulus produces change in variable.1
VARIABLE (in homeostasis)
IMBALANCE
Figure 1.4, step 1

18. IMBALANCE IMBALANCE Receptor Receptor detects change. Stimulus2
Stimulus
produces
change in
variable.
IMBALANCE 1
VARIABLE (in homeostasis)
IMBALANCE
Figure 1.4, step 2

19. Input: Information sent along afferent pathway to control center.3
Control
Center
Afferent
pathway
Receptor
Receptor detects change. 2
Stimulus
produces
change in
variable.
IMBALANCE 1
VARIABLE (in homeostasis)
IMBALANCE
Figure 1.4, step 3

20. Input: Information sent along afferent pathway to control center.3
Output: Information sent along efferent pathway to effector. 4
Control
Center
Afferent
pathway
Efferent
pathway
Receptor
Effector
Receptor detects change. 2
Stimulus
produces
change in
variable.
IMBALANCE 1
VARIABLE (in homeostasis)
IMBALANCE
Figure 1.4, step 4

21. Input: Information sent along afferent pathway to control center.3
Output: Information sent along efferent pathway to effector. 4
Control
Center
Afferent
pathway
Efferent
pathway
Receptor
Effector
Receptor detects change. 2
Response
of effector feeds
back to reduce
the effect of
stimulus and
returns variable
to homeostatic level. 5
Stimulus
produces
change in
variable.
IMBALANCE 1
VARIABLE (in homeostasis)
IMBALANCE
Figure 1.4, step 5

22. Maintaining Homeostasis
The body communicates through neural and hormonal control systems
Receptor
Responds to changes in the environment (stimuli)
Sends information to control center

23. Maintaining Homeostasis
Control center
Determines set point
Analyzes information
Determines appropriate response
Effector
Provides a means for response to the stimulus

24. Feedback Mechanisms Negative feedback
Includes most homeostatic control mechanisms
Shuts off the original stimulus, or reduces its intensity
Works like a household thermostat

25. Feedback Mechanisms 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