1. Characteristics and Maintenance of Life
Chapter 1
Characteristics and Maintenance of Life

2. Characteristics of Life
Ability to respond and adapt to the environment.

3. Characteristics of Life
Growth
Increase in mass.

4. Characteristics of Life
Growth and Development
Growth is increase in size.
Development is the formation of new structures.

5. Characteristics of Life
Reproduction
Ability to produce new organisms.

6. Characteristics of Life
Metabolism
Physical and chemical changes that occur through the digestion of a food source that allows an organism to obtain, release, and utilize energy.

7. Table 01.03

8. Maintenance of Life
Except for the reproductive system, and body structures and functions work in ways that maintain life.

9. Maintenance of Life Environmental factors needed for life: Water
Transports substances
Important for regulating body temperature
Required for many metabolic processes
Most abundant substance in the body

10. Maintenance of Life Environmental factors needed for life: Food
Provides energy and raw materials for building new living matter.

11. Maintenance of Life Environmental factors needed for life: Oxygen
Used in the process of releasing energy from food.

12. Maintenance of Life Environmental factors needed for life: Heat
Partly controls the rate at which metabolic reactions take place.
Heat is a form of energy. Temperature is a measurement of the amount of heat present.

13. Maintenance of Life Environmental factors needed for life: Pressure
Application of force on an object or substance.
Examples:
Atmospheric pressure
Caused by air particles
Hydrostatic pressure
Caused by particles of a liquid such as water
Blood pressure is a type of hydrostatic pressure

14. Table 01.04

15. Maintenance of Life Homeostasis
The maintenance of a stable internal environment.
Requires most of a human’s metabolic energy.
Homeostasis is maintained through self-regulating control systems called homeostatic mechanisms.

16. Maintenance of Life Homeostatic Mechanisms Have 3 components:
Receptors
Provide info about specific conditions (stimuli) in the internal environment.
Control Center
Tells what a particular value should be (set point).
Effectors
Elicit responses that alter conditions in the internal environment.

17. Maintenance of Life Homeostatic Mechanisms Have 3 components:
Receptors
Provide info about specific conditions (stimuli) in the internal environment.
Control Center
Tells what a particular value should be (set point).
Effectors
Elicit responses that alter conditions in the internal environment.

18. Maintenance of Life
Homeostatic Mechanisms

19. Maintenance of Life Homeostatic Mechanisms
Work through negative feedback.
If a change from the set point is detected by the receptors, the effectors are triggered to bring the conditions back (negative) to the set point.
As conditions get closer to the set point, the receptors begin to shut down so that conditions do not move past the set point.

20. Maintenance of Life Homeostatic Mechanisms
Although homeostasis is usually maintained through negative feedback, there are some positive feedback systems (which move conditions away from the normal) such as blood clotting that also contribute to homeostasis.

21. Homeostatic mechanism regulates body temperature
Slide number: 2
Stimulus
Body temperature
rises above normal.
too high
Normal body
Temperature
37oC (98.6oF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

22. Homeostatic mechanism regulates body temperature
Slide number: 3
Receptors
Thermoreceptors send
signals to the control center.
Stimulus
Body temperature
rises above normal.
too high
Normal body
Temperature
37oC (98.6oF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

23. Homeostatic mechanism regulates body temperature
Slide number: 4
Control center
The brain detects the
deviation from the set
point and signals effector
organs.
Receptors
Thermoreceptors send
signals to the control center.
Stimulus
Body temperature
rises above normal.
too high
Normal body
Temperature
37oC (98.6oF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

24. Homeostatic mechanism regulates body temperature
Slide number: 5
Control center
The brain detects the
deviation from the set
point and signals effector
organs.
Receptors
Thermoreceptors send
signals to the control center.
Effectors
Skin blood vessels dilate
and sweat glands secrete.
Stimulus
Body temperature
rises above normal.
too high
Normal body
Temperature
37oC (98.6oF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

25. Homeostatic mechanism regulates body temperature
Slide number: 2
Stimulus
Body temperature
rises above normal.
too high
Normal body
Temperature
37oC (98.6oF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

26. Homeostatic mechanism regulates body temperature
Slide number: 3
Receptors
Thermoreceptors send
signals to the control center.
Stimulus
Body temperature
rises above normal.
too high
Normal body
Temperature
37oC (98.6oF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

27. Homeostatic mechanism regulates body temperature
Slide number: 4
Control center
The brain detects the
deviation from the set
point and signals effector
organs.
Receptors
Thermoreceptors send
signals to the control center.
Stimulus
Body temperature
rises above normal.
too high
Normal body
Temperature
37oC (98.6oF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

28. Homeostatic mechanism regulates body temperature
Slide number: 5
Control center
The brain detects the
deviation from the set
point and signals effector
organs.
Receptors
Thermoreceptors send
signals to the control center.
Effectors
Skin blood vessels dilate
and sweat glands secrete.
Stimulus
Body temperature
rises above normal.
too high
Normal body
Temperature
37oC (98.6oF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

29. Homeostatic mechanism regulates body temperature
Slide number: 6
Control center
The brain detects the
deviation from the set
point and signals effector
organs.
Receptors
Thermoreceptors send
signals to the control center.
Effectors
Skin blood vessels dilate
and sweat glands secrete.
Stimulus
Body temperature
rises above normal.
Response
Body heat is lost to surroundings,
temperature drops toward normal.
too high
Normal body
Temperature
37oC (98.6oF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

30. Homeostatic mechanism regulates body temperature
Slide number: 7
Normal body
Temperature
37oC (98.6oF)
too low
Stimulus
Body temperature
drops below normal.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

31. Homeostatic mechanism regulates body temperature
Slide number: 8
Normal body
Temperature
37oC (98.6oF)
too low
Stimulus
Body temperature
drops below normal.
Receptors
Thermoreceptors send
signals to the control center.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

32. Homeostatic mechanism regulates body temperature
Slide number: 9
Normal body
Temperature
37oC (98.6oF)
too low
Stimulus
Body temperature
drops below normal.
Receptors
Thermoreceptors send
signals to the control center.
Control center
The brain detects the
deviation from the set point
and signals effector organs.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

33. Homeostatic mechanism regulates body temperature
Slide number: 10
Normal body
Temperature
37oC (98.6oF)
too low
Stimulus
Body temperature
drops below normal.
Receptors
Thermoreceptors send
signals to the control center.
Control center
The brain detects the
deviation from the set point
and signals effector organs.
If body temperature
continues to drop, control
center signals muscles to
contract involuntarily.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

34. Homeostatic mechanism regulates body temperature
Slide number: 11
Normal body
Temperature
37oC (98.6oF)
too low
Stimulus
Body temperature
drops below normal.
Receptors
Thermoreceptors send
signals to the control center.
Effectors
Skin blood vessels constrict and
sweat glands remain inactive.
Effectors
Muscle activity
generates body heat.
Control center
The brain detects the
deviation from the set point
and signals effector organs.
If body temperature
continues to drop, control
center signals muscles to
contract involuntarily.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

35. Homeostatic mechanism regulates body temperature
Slide number: 12
Normal body
Temperature
37oC (98.6oF)
too low
Stimulus
Body temperature
drops below normal.
Response
Body heat is conserved,
temperature rises toward normal.
Receptors
Thermoreceptors send
signals to the control center.
Effectors
Skin blood vessels constrict and
sweat glands remain inactive.
Effectors
Muscle activity
generates body heat.
Control center
The brain detects the
deviation from the set point
and signals effector organs.
If body temperature
continues to drop, control
center signals muscles to
contract involuntarily.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.