1. The Human Body: An Orientation
Chapter 1 introduces and establishes the framework upon which all the other chapters are built. This chapter provides the necessary terminology so that instructor and students are all “speaking the same language.” Marieb begins by defining the key terms anatomy and physiology, and then continues to describe the ways in which these key terms are interrelated. It is important that students realize that structure determines function, since that concept will help them to master the more difficult material in future chapters.
Levels of organization are presented next, beginning with the atomic level and continuing through to the highest level of organization, the human body. A brief overview of the various organ systems follows the discussion of the levels of structural organization, and the ways in which all the organ systems are interconnected into a working whole. This concept is further augmented by the discussion of the necessary life functions, since it is important for students to understand that each of the organ systems has several functions, and that any given function (e.g., excretion) is actually carried out by several organ systems working together to maintain appropriate balance within the living organism. This information leads to a discussion of homeostasis, and the disease states that occur when homeostatic mechanisms are out of balance for extended periods. Students appreciate the image of the dynamic body continually striving to maintain balance and equilibrium.
The final section of this chapter provides the basic terminology that will be used and expanded upon throughout the text. Directional terms help the student distinguish between relative terms such as proximal and distal, and thus help them understand the midline of the body as an axis point. Regional terms differentiate anterior and posterior body landmarks, divide the body into sections and planes, and identify the body cavities and their components. The anatomists’ useful description of regions is also presented to round out the students’ awareness of the ways in which the body can be physically and intellectually dissected.

2. The Human Body—An Orientation
Anatomy
Study of the structure and shape of the body and its parts
Physiology
Study of how the body and its parts work or function
Anatomy Refers to the body’s framework and its organ composition.
Physiology refers to the action of each part of the body.
example:
liver – is responsible for metabolism
kidneys – is involved in the excretion of body waste.

3. Anatomy—Levels of Study
Gross anatomy
Large structures
Easily observable
When we study the structure of the human body, we look at the large picture, known as GROSS ANATOMY, means we focus on the structure that is big enough to be observed.
Figure 14.1

4. Anatomy—Levels of Study
Microscopic Anatomy
Very small structures
Can only be viewed with a microscope
But if we look on the smaller parts of the human body, means we study the MICROSCOPIC ANATOMY, which refers to the very small structures such as the cell or the nerves in the body.
Figure 14.4c–d

5. Levels of Structural Organization
Molecules
Atoms
Chemical level Atoms combine to form molecules
Figure 1.1, step 1

6. Levels of Structural Organization
Smooth muscle cell
Molecules
Atoms
Cellular level Cells are made up of molecules
Chemical level Atoms combine to form molecules
Figure 1.1, step 2

7. Levels of Structural Organization
Smooth muscle cell
Molecules
Atoms
Smooth muscle tissue
Cellular level Cells are made up of molecules
Tissue level Tissues consist of similar types of cells
Chemical level Atoms combine to form molecules
Figure 1.1, step 3

8. Levels of Structural Organization
Smooth muscle cell
Molecules
Atoms
Smooth muscle tissue
Epithelial tissue
Connective tissue
Blood vessel (organ)
Cellular level Cells are made up of molecules
Tissue level Tissues consist of similar types of cells
Organ level Organs are made up of different types of tissues
Chemical level Atoms combine to form molecules
Figure 1.1, step 4

9. Levels of Structural Organization
Smooth muscle cell
Molecules
Atoms
Smooth muscle tissue
Epithelial tissue
Connective tissue
Blood vessel (organ)
Cardio- vascular system
Cellular level Cells are made up of molecules
Tissue level Tissues consist of similar types of cells
Organ level Organs are made up of different types of tissues
Organ system level Organ systems consist of different organs that work together closely
Chemical level Atoms combine to form molecules
Figure 1.1, step 5

10. Levels of Structural Organization
Smooth muscle cell
Molecules
Atoms
Smooth muscle tissue
Epithelial tissue
Connective tissue
Blood vessel (organ)
Cardio- vascular system
Cellular level Cells are made up of molecules
Tissue level Tissues consist of similar types of cells
Organ level Organs are made up of different types of tissues
Organ system level Organ systems consist of different organs that work together closely
Organismal level Human organisms are made up of many organ systems
Chemical level Atoms combine to form molecules
Figure 1.1, step 6

11. Organ System Overview Integumentary Forms the external body covering
Protects deeper tissue from injury
Helps regulate body temperature
Location of cutaneous nerve receptors
Figure 1.2a

12. Organ System Overview Skeletal Protects and supports body organs
Provides muscle attachment for movement
Site of blood cell formation
Stores minerals
Figure 1.2b

13. Organ System Overview Muscular Produces movement Maintains posture
Produces heat
Figure 1.2c

14. Organ System Overview Nervous Fast-acting control system
Responds to internal and external change
Activates muscles and glands
Figure 1.2d

15. Organ System Overview Endocrine Secretes regulatory hormones Growth
Reproduction
Metabolism
Figure 1.2e

16. Organ System Overview Cardiovascular
Transports materials in body via blood pumped by heart
Oxygen
Carbon dioxide
Nutrients
Wastes
Figure 1.2f

17. Organ System Overview Lymphatic Returns fluids to blood vessels
Cleanses the blood
Involved in immunity
Figure 1.2g

18. Organ System Overview Respiratory Keeps blood supplied with oxygen
Removes carbon dioxide
Figure 1.2h

19. Organ System Overview Digestive Breaks down food
Allows for nutrient absorption into blood
Eliminates indigestible material
Figure 1.2i

20. Organ System Overview Urinary Eliminates nitrogenous wastes
Maintains acid-base balance
Regulates water and electrolytes
Figure 1.2j

21. Organ System Overview
Reproductive
Produces offspring
Figure 1.2k–l

22. Necessary Life Functions
Maintain boundaries
Movement
Locomotion
Movement of substances
Responsiveness
Ability to sense changes and react
Digestion
Break-down and absorption of nutrients

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

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

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

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

27. Interrelationships Among Body Systems
Figure 1.3

28. 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

29. 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

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

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

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

33. 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

34. 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

35. 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

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

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

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

39. 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

40. Prepare ½ crosswise