CCM4
Human Anatomy & Physiology with
Pathophysiology
HOMEOSTASIS
 homeo – the same; stasis – to stop
 The existence and maintenance of a
relatively constant environment within the
body despite fluctuations in either the
external environment or the internal
environment.
 Maintenance of a stable environment
 A dynamic state of an equilibrium
 Necessary for normal body
functioning and to sustain life.
 Homeostatic Imbalance
 A disturbance in Homeostasis
resulting in disease.
SET POINTS FOR SOME VARIABLES CAN
BE TEMPORARILY ADJUSTED DEPENDING
ON BODY ACTIVITIES, AS NEEDED:
Examples
body temperature
Heart rate, blood
pressure respiratory
rate
Common cause of
change
fever
exercise
COMPONENTS OF HOMEOSTATIC MECHANISM
Maintaining Homeostasis
 The body communicates through neural
and hormonal control system.
Variables
 Measures of body properties that may
change in value.
Examples of variables:
 Body temperature (36.5 – 37.5OC)
 HEART RATE (60 – 100 bpm)
 BLOOD PRESSURE (<120/80 mm Hg)
 BLOOD GLUCOSE LEVELS (70
mg/dL– 100 mg/dL
 BLOOD CELL COUNTS
HOMEOSTASIS
 NORMAL RANGE: normal extent of
increase or decrease around a set point.
 SET POINT: normal, or average value of
a variable over time, body temperature
fluctuates around a set point.

Receptor
 Responds to changes in the
environment (stimuli)
 Sends information to the control
center

Control center
• Determines set point
• Analyzes information
• Determines appropriate response
 Effector
 Provides a means for response to the
stimulus
HOMEOSTASIS
• A NEGATIVE FEEDBACK RESPONSE
INVOLVES: DETECTION: OF DEVIATION
AWAY FROM SET POINT AND
CORRECTION: REVERSAL OF DEVIATION
TOWARD SET POINT AND NORMAL RANGE
• Any deviation from the set point is made