Feedback systems (Ch 1) Flashcards
Most homeostatic control mechanisms are
negative feedback mechanisms
Negative feedback causes the variable to change in a direction
opposite to the original change
When the variable goes in the opposite direction
the “ideal” value is achieved.
In negative feedback, the output or response shuts off the
original stimulus or reduces its intensity.
What doe the nervous system control
Regulating body temp, withdrawal reflex
Regulating body temp is controlled by what part of the brain
hypothalamus
what does the Endocrine System controls
Blood glucose levels (pancreatic hormones)
To carry out normal metabolism, body cells need to have a constant supply of
glucose
the major source for producing energy (ATP)
glucose
in the endocrine system, in normal metabolism, the stimulus is the rising
blood glucose level (too much sugar)
In the endocrine system, the increase in sugar levels stimulate the
insulin-producing cells of the pancreas – (receptor).
known as the control center in the endocrine system
pancreas
Where do the pancreas release insulin
into the blood
The pancreas releasing insulin into the blood does what
speeds up the uptake of glucose by most of the body cells
The pancreas also encourages the liver and muscles to
store excess glucose and glycogen – effector so that there is a reserve supply when needed
What is the goal of all negative feedback mechanisms
to prevent severe changes within the body
Other areas controlled via negative feedback
Heart rate Blood pressure Rate and depth of breathing Blood oxygen levels Carbon dioxide levels Minerals
Control infrequent events that don’t require continuous adjustments
Positive feedback
Enhances the original stimulus so the activity (output) is accelerated
Positive feedback
Why is positive feedback positive
the change that occurs is in the same direction as the initial disturbance
Once initiated, there is a series of events which sort of lead to what kind of affect
Waterfall
Positive feedback is also referred to as
Cascades
Two main areas of positive feedback are
enhancement of labor contractions
blood clotting
Most disease is thought to be a result of what kind of disturbance
homeostatic; homeostatic imbalance
Can also occur when the normal negative feedback mechanisms are overwhelmed and destructive positive feedback mechanisms take over
Homeostatic Imbalance
