Section 38.2 (Exam 3) Flashcards
Physiological Systems Maintain Homeostasis of the Internal Environment
How do individual cells use the extracellular fluid (ECF)?
They get nutrients from it and dump wastes into it
What does the ECF consist of?
20% blood plasma and 80% interstitial fluid
Organisms must maintain homeostasis. What is homeostasis?
a narrow range of stable and optimal physical and biochemical conditions
What organ systems control the activities of the physiological systems?
The nervous and endocrine systems
What is the set point?
a reference point (e.g. the desired body temperature)
What is a comparator?
Senses the current point and compares it to the reference point (e.g. sense the current body temperature and compares it to the ideal body temperature)
What is feedback?
the information that is compared to the set point (e.g. the current body temperature)
What is the error signal?
any difference between the set point and the feedback (e.g. body temperature is 101 instead of 98.6)
What is the function of regulatory systems?
obtain, integrate, and process information and issue commands to effectors such as muscles or glands that effect changes in the internal environment
Why are effectors called controlled systems?
they are controlled by neural or hormonal signals from regulatory systems
What is the function of sensors?
provide the feedback information
What are the two types of feedback?
Negative and positive feedback
What is negative feedback?
mechanism that counteracts changes and negates deviation from the set point. (e.g. reduced body temp, shivering)
What is positive feedback?
amplifies a response and increases deviation from a set point (e.g. contractions during birth)
responses tend to reach a limit and terminate rapidly (e.g. contractions end after childbirth)
What is feedforward information?
anticipates internal changes and changes the set point (e.g. body releasing insulin before food enters bloodstream)
