Homeostasis Flashcards
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
homeostasis
- maintenance of a stable internal environment
- a dynamic state of equilibrium
- necessary for normal body functioning and to sustain life
homeostasis
a disturbance in homeostasis resulting in disease
homeostatic imbalance
the body communicates through ____ and _____ control systems
neural and hormonal
variables of homeostasis
(measures of body properties that may change in value)
- 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
- RESPIRATORY RATE (12 – 16 breaths per
minute)
normal extent of increase or decrease around a set point
normal range
normal, or average value of a variable over time, body temperature fluctuates around this
set point
- responds to changes in the environment (stimuli)
- send information to the control center
receptor
- determines set point
- analyzes information
- determines appropriate response
control center
provides a means for response to the stimulus
effector
THE MAIN MECHANISM USED in HOMEOSTATIC REGULATION
negative feedback
DEVIATION AWAY FROM SET POINT
DETECTION
REVERSAL OF DEVIATION TOWARD SET
POINT AND NORMAL RANGE
CORRECTION
any deviation from the set point is made ____ or is _____
smaller or is resisted
MECHANISMS OCCUR WHEN THE INITIAL
STIMULUS FURTHER STIMULATES THE RESPONSE
A SPECIAL CASE
POSITIVE FEEDBACK
- SYSTEM RESPONSE CAUSES PROGRESSIVE DEVIATION AWAY FROM
- SET POINT, OUTSIDE OF NORMAL RANGE
- NOT DIRECTLY USED FOR HOMEOSTASIS
- SOME POSITIVE FEEDBACK OCCURS UNDER NORMAL CONDITIONS
POSITIVE FEEDBACK
stretching of uterine walls causes contractions that further stretch the walls (continues until birthing occurs)
childbirth
child feeding stimulates milk production which causes further feeding (continues until the baby stops feeding)
lactation
the dominant follicle releases estrogen which stimulates LH and FSH release to promote further follicular growth
ovulation
platelets release clotting factors which cause more platelets to aggregate at the site of injury
blood clotting
