PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

PART B1

The Human Body: An Orientation

Figure 1.2f

Organ System Overview

• Cardiovascular System– Transports materials in body

via blood pumped by heart• Oxygen• Carbon dioxide• Nutrients• Wastes

Organ System Overview• Lymphatic System– Returns fluids to blood

vessels– Cleanses the blood– Involved in immunity

Figure 1.2g

Organ System Overview• Respiratory System– Keeps blood supplied with

oxygen– Removes carbon dioxide

Figure 1.2h

Organ System Overview• Digestive System– Breaks down food– Allows for nutrient

absorption into blood– Eliminates indigestible

material

Figure 1.2i

Organ System Overview• Urinary System– Eliminates nitrogenous

wastes– Maintains acid-base balance– Regulates water and

electrolytes– Checkpoint:– At which level of structural

organization is the stomach? Organ– Which organ system includes the

Pineal, Thyroid, Thymus and Adrenal Glands?

EndocrineFigure 1.2j

Organ System Overview• Reproductive System– Produces offspring

Figure 1.2k–l

Necessary Life Functions• Maintain boundaries• Movement– Locomotion of body/body parts– Movement of substances

• Responsiveness– Ability to sense changes and react

• Digestion– Break-down and absorption of nutrients

Survival Needs• Nutrients– Chemicals for energy and cell building– Includes carbohydrates, proteins, lipids,

vitamins, and minerals• Oxygen– Required for the chemical reactions of digestion

& respiration (cellular metabolism)

Survival Needs• Water– 60–80% of body weight– Provides fluids for metabolic reactions

• Stable body temperature• Metabolic reactions occur most efficiently within a

specific temperature range (36.1-37.5 oC = 96.9-99.5 oF)

• Atmospheric pressure – Must be appropriate for exchange of gases in

lungs in a timely manner to maintain cellular respiration

Interrelationships Among Body Systems

Figure 1.3

Organ systems work together to promote the well-being of the entire body by completing necessary life functions.

Checkpoint: Why is O2 so vital to survival?

Homeostasis• Homeostasis—maintenance of a stable internal

environment – A dynamic state of equilibrium– Continuous changes (within limits) that maintain

overall balance within the body• Homeostasis is necessary for normal body

functioning and to sustain life• Homeostatic Imbalance– A disturbance in homeostasis resulting in disease– Increasing age results in less stable internal

conditions, which leads to increased risk for illness

Controlling Homeostasis• The body uses electrical and hormonal control

signals through the nervous and endocrine systems to constantly monitor and control homeostasis.

• Three essential components of the control systems:1. Receptor• Responds to changes in the environment (stimuli)• Sends information to control center

Maintaining Homeostasis

2. Control Center• Determines set point (optimum level) for

variable• Analyzes information• Determines appropriate response

3. Effector• Provides a means for response to the stimulus

Figure 1.4, step 5

Input: Information sent along afferent pathway to control center.

Receptor

ControlCenter

Effector Receptor detects change.

Afferentpathway

Efferentpathway

IMBALANCE

VARIABLE (in homeostasis)

Stimulusproduceschange invariable.

Output: Information sent along efferent pathway to effector.

Responseof effector feedsback to reducethe effect ofstimulus andreturns variableto homeostatic level.

1

3 4

5

IMBALANCE

2

Maintaining Homeostasis

ApproachesControl Center Exits

Control Center

Feedback Mechanisms

• Negative Feedback– Includes most homeostatic control mechanisms– Shuts off the original stimulus, or reduces its

intensity– Works like a household thermostat– Examples: heart rate, blood pressure, respiration rate, glucose levels

Feedback Mechanisms• Positive Feedback– Increases the original stimulus to push the

variable farther away from original value– Reaction continues at a faster rate– Examples: blood clotting, childbirth

• Checkpoint: When you are thirsty, you drink water. Is the thirst

sensation part of a negative feedback or a positive feedback mechanism? Why?