1. The Human Body: An Orientation
TOPICS
Necessary Life Functions
Survival Needs
Homeostasis

2. Necessary Life Functions
Maintain boundaries (cell structure included)
Movement
Locomotion
Movement of substances
Responsiveness
Ability to sense changes and react
Digestion
Break-down and absorption of nutrients

3. Necessary Life Functions
Metabolism—chemical reactions within the body
Produces energy
Makes body structures
Excretion
Eliminates waste from metabolic reactions

4. Necessary Life Functions
Reproduction
Produces future generation
Growth
Increases cell size and number of cells

5. Check For Understanding
What organ system helps the body as a whole maintain its boundaries?
Life Function = Maintain Boundaries

6. Integumentary System (Skin)
Answer
Integumentary System (Skin)

7. Check For Understanding
What organ system allows for movement of the human organism as a whole?
Life Function = Movement

8. But not by itself…..along with what other system?
Answer
Muscular System
But not by itself…..along with what other system?

9. Movement doesn’t occur if the muscles aren’t attached to bony levers
Answer
Skeletal System
Movement doesn’t occur if the muscles aren’t attached to bony levers

10. Check For Understanding
What system allows for movement of substances within the human organism?
Life Function = Movement

11. Cardio-Vascular System
Answer
Cardio-Vascular System
But if it weren’t for what other systems, the CV system wouldn’t have gases or nutrients to transport?

12. Respiratory and Digestive Systems
Answer
Respiratory and Digestive Systems

13. Check For Understanding
What two body systems act together to respond to external/internal changes and maintain the bodies homeostatic environment?

14. Nervous and Endocrine Systems
Answer
Nervous and Endocrine Systems

15. Survival Needs Nutrients Chemicals for energy and cell building
Includes carbohydrates, proteins, lipids, vitamins, and minerals (your food)
Oxygen
Required for chemical reactions

16. Survival Needs Water 60–80% of body weight
Provides for metabolic reaction
Stable body temperature
Atmospheric pressure
Must be appropriate

17. Interrelationships Among Body Systems
Figure 1.3

18. 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

19. Variable (in homeostasis)
Input: Information sent along afferent pathway to
Control center
Output: Information sent along efferent pathway to activate
Receptor (sensor)
Effector
Change detected by receptor
Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis
Stimulus: Produces change in variable
Imbalance
Variable (in homeostasis)
Imbalance
Figure 1.4

20. Variable (in homeostasis)
Figure 1.4, step 1a

21. Variable (in homeostasis)
Stimulus: Produces change in variable
Imbalance
Variable (in homeostasis)
Imbalance
Figure 1.4, step 1b

22. Variable (in homeostasis)
Receptor (sensor)
Change detected by receptor
Stimulus: Produces change in variable
Imbalance
Variable (in homeostasis)
Imbalance
Figure 1.4, step 2

23. Variable (in homeostasis)
Input: Information sent along afferent pathway to
Control center
Receptor (sensor)
Change detected by receptor
Stimulus: Produces change in variable
Imbalance
Variable (in homeostasis)
Imbalance
Figure 1.4, step 3

24. Variable (in homeostasis)
Input: Information sent along afferent pathway to
Control center
Output: Information sent along efferent pathway to activate
Receptor (sensor)
Effector
Change detected by receptor
Stimulus: Produces change in variable
Imbalance
Variable (in homeostasis)
Imbalance
Figure 1.4, step 4

25. Variable (in homeostasis)
Input: Information sent along afferent pathway to
Control center
Output: Information sent along efferent pathway to activate
Receptor (sensor)
Effector
Change detected by receptor
Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis
Stimulus: Produces change in variable
Imbalance
Variable (in homeostasis)
Imbalance
Figure 1.4, step 5

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

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

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

29. 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

30. Steps In a Negative Feedback Loop