The Human Body: An Orientation TOPICS Necessary Life Functions Survival Needs Homeostasis

Necessary Life Functions Maintain boundaries (cell structure included) Movement Locomotion Movement of substances Responsiveness Ability to sense changes and react Digestion Break-down and absorption of nutrients

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

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

Check For Understanding What organ system helps the body as a whole maintain its boundaries? Life Function = Maintain Boundaries

Integumentary System (Skin) Answer Integumentary System (Skin)

Check For Understanding What organ system allows for movement of the human organism as a whole? Life Function = Movement

But not by itself…..along with what other system? Answer Muscular System But not by itself…..along with what other system?

Movement doesn’t occur if the muscles aren’t attached to bony levers Answer Skeletal System Movement doesn’t occur if the muscles aren’t attached to bony levers

Check For Understanding What system allows for movement of substances within the human organism? Life Function = Movement

Cardio-Vascular System Answer Cardio-Vascular System But if it weren’t for what other systems, the CV system wouldn’t have gases or nutrients to transport?

Respiratory and Digestive Systems Answer Respiratory and Digestive Systems

Check For Understanding What two body systems act together to respond to external/internal changes and maintain the bodies homeostatic environment?

Nervous and Endocrine Systems Answer Nervous and Endocrine Systems

Survival Needs Nutrients Chemicals for energy and cell building Includes carbohydrates, proteins, lipids, vitamins, and minerals (your food) Oxygen Required for chemical reactions

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

Interrelationships Among Body Systems Figure 1.3

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

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

Variable (in homeostasis) Figure 1.4, step 1a

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

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

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

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

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

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

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

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

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

Steps In a Negative Feedback Loop