anatomy and physiology ch 1b lecture human body

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin CummingsCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Human Anatomy & Physiology, Sixth EditionElaine N. Marieb

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky

1The Human Body: An Orientation

Part B

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Today! We will learn about…….

Life functions and survival needs Homeostasis and Feedback

mechanisms Anatomical position and

directional terms


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



Movement – locomotion, propulsion (peristalsis), and contractility

Responsiveness – ability to sense changes in the environment and respond to them

Digestion – breakdown of ingested foodstuffs



Metabolism – all the chemical reactions that occur in the body

Excretion – removal of wastes from the body


Necessary Life Functions Reproduction – cellular and

organismal levelsCellular – 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


Survival Needs

Nutrients – chemical substances used for energy and cell building

Oxygen – needed for metabolic reactions

Water – provides the necessary environment for chemical reactions


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


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


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


Stimulus:Produceschangein variable

1

2

3

Changedetectedby receptor

Input:Informationsent alongafferentpathway to

5 Response ofeffector feedsback to influencemagnitude of stimulus andreturnsvariable tohomeostasis

Variable (in homeostasis)

Imbalance

Imbalance

Receptor (sensor)

Controlcenter 4 Output:

Information sentalong efferentpathway to

Effector

Homeostatic Control Mechanisms

Figure 1.4


Negative Feedback

In negative feedback systems, the output shuts off the original stimulus

Example: Regulation of blood glucose levels


Negative Feedback

Figure 1.5


Positive Feedback

In positive feedback systems, the output enhances or exaggerates the original stimulus

Example: Regulation of blood clotting

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


Anatomical Position

Body erect, feet slightly apart, palms facing forward, thumbs point away from body

Figure 1.7a


Directional Terms

Superior– toward the head

Inferior –away from the head


Directional Terms

Anterior– toward the front of the body

Posterior – toward the back of the body


Directional Terms

Medial– toward the midline Lateral - away from the midline Intermediate –between a more

medial and lateral structure


Directional Terms

Proximal – closer to the origin of the body

Distal – farther from the origin of the body


Directional Terms

Superficial – toward the body surface

Deep –away from the body surface


Directional Terms

Table 1.1


Regional Terms: Anterior View

Axial – head, neck, and trunk

Appendicular – appendages or limbs

Specific regional terminology

Figure 1.7a


Regional Terms: Posterior View

Figure 1.7b


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


Quiz next time over the material in this lecture! Quiz next time over the material in this lecture!

Work on study guide – Will be a check on pages 11-16

anatomy and physiology ch 1b lecture human body

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