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PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky
The Human Body:
An Orientation
Part B
Human Anatomy & Physiology, Sixth Edition
Elaine N. Marieb
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
1
Today! We will learn about…….
 Life functions and survival needs
 Homeostasis and Feedback
mechanisms
 Anatomical position and directional
terms
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Necessary Life Functions
 Maintaining boundaries – the internal
environment remains distinct from
the external
 Cellular level – accomplished by
plasma membranes
 Organismal level – accomplished by
the skin
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Necessary Life Functions
 Movement – locomotion, propulsion
(peristalsis), and contractility
 Responsiveness – ability to sense
changes in the environment and
respond to them
 Digestion – breakdown of ingested
foodstuffs
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Necessary Life Functions
 Metabolism – all the chemical
reactions that occur in the body
 Excretion – removal of wastes from
the body
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Necessary Life Functions
 Reproduction – cellular and
organismal levels
 Cellular – an original cell divides and
produces two identical daughter
cells
 Organismal – sperm and egg unite
to make a whole new person
 Growth – increase in size of a body
part or of the organism
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Survival Needs
 Nutrients – chemical substances used
for energy and cell building
 Oxygen – needed for metabolic
reactions
 Water – provides the necessary
environment for chemical reactions
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Survival Needs
 Maintaining normal body temperature
– necessary for chemical reactions to
occur at life-sustaining rates
 Atmospheric pressure – required for
proper breathing and gas exchange in
the lungs
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Homeostasis
 Homeostasis is the ability to maintain
a relatively stable internal
environment in an ever-changing
outside world
 The internal environment of the body
is in a dynamic state of equilibrium
 Chemical, thermal, and neural factors
interact to maintain homeostasis
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Homeostatic Control Mechanisms
 The variable produces a change in the body
 The three interdependent components of
control mechanisms are:
 Receptor – monitors the environments and
responds to changes (stimuli)
 Control center – determines the set point at
which the variable is maintained
 Effector – provides the means to respond to
the stimulus
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Homeostatic Control Mechanisms
3 Input:
Information
sent along
afferent
pathway to
Control
center
4 Output:
Information sent
along efferent
pathway to
Effector
Receptor (sensor)
2 Change
detected
by receptor
1
Stimulus:
Produces
change
in variable
Variable (in homeostasis)
5 Response of
effector feeds
back to influence
magnitude of
stimulus and
returns
variable to
homeostasis
Figure 1.4
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Negative Feedback
 In negative feedback systems, the
output shuts off the original stimulus
 Example: Regulation of blood glucose
levels
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Negative Feedback
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 1.5
Positive Feedback
 In positive
feedback
systems, the
output enhances
or exaggerates
the original
stimulus
 Example:
Regulation of
blood clotting
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 1.6
Homeostatic Imbalance
 Disturbance of homeostasis or the
body’s normal equilibrium
 Overwhelming of negative feedback
mechanisms allowing destructive
positive feedback mechanisms to
take over
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Anatomical Position
 Body erect,
feet slightly
apart, palms
facing forward,
thumbs point
away from body
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 1.7a
Directional Terms
 Superior– toward the head
 Inferior –away from the head
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Directional Terms
 Anterior– toward the front of the
body
 Posterior – toward the back of the
body
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Directional Terms
 Medial– toward the midline
 Lateral - away from the midline
 Intermediate –between a more medial
and lateral structure
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Directional Terms
 Proximal – closer to the origin of the
body
 Distal – farther from the origin of
the body
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Directional Terms
 Superficial – toward the body
surface
 Deep –away from the body surface
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Directional Terms
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Table 1.1
Directional Terms
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Table 1.1
Regional Terms: Anterior View
 Axial – head,
neck, and
trunk
 Appendicular –
appendages or
limbs
 Specific
regional
terminology
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 1.7a
Regional Terms: Posterior View
Figure 1.7b
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Anatomical Variability
 Humans vary slightly in both external and
internal anatomy
 Over 90% of all anatomical structures
match textbook descriptions, but:
 Nerves or blood vessels may be
somewhat out of place
 Small muscles may be missing
 Extreme anatomical variations are
seldom seen
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Quiz next time over the
material in this lecture!
Work on study guide – Will
be a check on pages 11-16
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings