maintaining life. survival needs nutrients consumed chemical substances that are used for energy...
TRANSCRIPT
Maintaining Life
Survival Needs
Nutrients Consumed chemical
substances that are used for energy and cell building
Survival Needs cont.
Oxygen Required by the
chemical reactions that release energy from foods
Survival Needs cont.
Water The most abundant
chemical substance in the body
Provides an environment for chemical reactions
Fluid medium for secretions of the body to occur at the proper rate.
Survival Needs cont
Normal Body Temperature Required for the
chemical reactions of the body to occur at the proper rate
Survival Needs cont
Atmospheric Pressure Must be within an
appropriate range so that proper gas exchange occurs in the lungs
Homeostasis
Homeostasis: All body systems working together to maintain a stable internal environment
Failure to function within a normal range results in disease
Mechanisms of Regulation
Autoregulation (intrinsic): automatic response in a cell, tissue, or
organ Extrinsic regulation:
responses controlled by nervous and endocrine systems
Homeostatic Control Mechanisms Receptor:
receives the stimulus (monitors changes in the environment & sends information to the control center)
Control center: processes the signal and sends instructions
(determines the set point, analyzes input, & coordinates response)
Effector: carries out instructions (directed by control center)
Maintaining Normal Limits
Negative Feedback Mechanisms
The response of the effector negates the stimulus (causes the variable to change in a way that opposes the initial change)
Most homeostatic control mechanisms are negative feedback
Negative Feedback Mechanisms cont.
Both the nervous system & the endocrine system are important to the maintenance of homeostasis
Goal of negative feedback is to prevent sudden, severe changes in the body
Positive Feedback Mechanisms The response of the effector reinforces the
stimulus
Positive Feedback Mechanisms cont.
A positive feedback mechanism causes the variable to change in the same direction as the original change, resulting in a greater deviation from the set point
Typically activate events that are self-perpetuating
Most positive feedback mechanisms are not related to the maintenance of homeostasis
Working Together
Working Together
Systems integration: systems work together to
maintain homeostasis
KEY CONCEPT
Homeostasis is a state of equilibrium: opposing forces are in balance
Physiological systems work to restore balance
Failure results in disease or death