1. Levels of Organization
Life is built on successive levels of increasing complexity:
Chemical (or Molecular)
Cellular
Tissue
Organ
Organ System
Organism

2. Organ Organism System Level Level Organ Level Tissue Level Chemical or
Endocrine
Cardiovascular
Lymphatic
Nervous
Respiratory
Muscular
Digestive
Skeletal
Urinary
Integumentary
Reproductive
Organ
Level
The
heart
Cardiac
muscle
tissue
Atoms in
combination
Tissue Level
Heart
muscle
cell
Complex protein
molecule
Protein filaments
Chemical or
Molecular Level
Cellular Level

3. Overview of Organ Systems
The human body is arranged in 11 organ systems:
Integumentary
Skeletal
Muscular
Nervous
Endocrine
Cardiovascular
Lymphatic
Respiratory
Digestive
Urinary
Reproductive

5. The Integumentary System
Figure 1-2(a)

6. The Skeletal System
Figure 1-2(b)

7. The Muscular System
Figure 1-2(c)

8. The Nervous System
Figure 1-2(d)

9. The Endocrine System
Figure 1-2(e)

10. The Cardiovascular System
Figure 1-2(f)

11. The Lymphatic System
Figure 1-2(g)

12. The Respiratory System
Figure 1-2(h)

13. The Digestive System
Figure 1-2(i)

14. The Urinary System
Figure 1-2(j)

15. Male Reproductive System
Figure 1-2(k)

16. Female Reproductive System
Figure 1-2(l)

17. Introduction to Organ Systems
The body can be divided into 11 organ systems, but all work together and the boundaries between them aren’t absolute.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

18. Homeostatic Regulation
Homeostasis
Maintains stable internal conditions
Temperature
Ionic concentrations
Blood sugar levels, etc.
Utilizes negative feedback mechanisms
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

19. Homeostatic Regulation
Regulation depends on:
Receptor sensitive to a particular stimulus
Effector that affects the same stimulus
RECEPTOR
Thermometer
STIMULUS:
Room temperature
rises
Normal
condition
disturbed
HOMEOSTASIS
room
temperature
RESPONSE:
drops
restored
EFFECTOR
Air conditioner
turns on
Sends
commands to
Information
affects
CONTROL CENTER
(Thermostat)
20o
30o
40o
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

20. Homeostatic Regulation
Negative Feedback:
Variation outside normal limits triggers automatic corrective response
Response negates disturbance
RECEPTOR
Body’s
temperature
sensors
STIMULUS
Body temperature
rises above 37.2oC
(99oF)
RESPONSE
Increased blood flow
to skin
Increased sweating
Stimulus removed
Homeostasis restored
Control
mechanism
when body
rises
EFFECTOR
Blood vessels
and sweat
glands in skin
Negative
feedback
Sends
commands to
Information
affects
CONTROL
CENTER
Thermoregulatory
center in brain
and sweat glands
in skin
Skeletal muscles
falls
falls below 37.2oC
Decreased blood flow
Decreased sweating
Shivering

21. Homeostatic Regulation
Positive Feedback:
Stimulus produces response that reinforces the stimulus
Response rapidly completes critical process
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

22. Homeostatic Regulation
Homeostasis and Disease
Failure of homeostatic regulation
Symptoms appear
Organ system malfunction
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings