Name: _____________________________________ Date: __________ Class: ______
Review
B.11A: Homeostasis
B.11A: Describe the role of internal feedback mechanisms in the maintenance of
homeostasis.
Supporting Standard
1. Homeostasis refers to the ‘steady state’ that all living organisms' systems
maintain. Homeostatic controls are used to keep factors such as body
temperature and blood pressure fairly constant despite changes in the
surrounding environment. The mechanisms for homeostasis include a control
center, receptor, and effector.
2. Most regulatory systems consists of negative feedback mechanisms, or triggers,
to counteract an internal fluctuation; like sweating to dispose of metabolic heat
in order to cool the body and maintain a constant body temperature. A positive
feedback mechanism involves a change that triggers the body to amplify a
change, like the contractions of childbirth in mammals. In animals, homeostatic
mechanisms are controlled by the nervous and endocrine systems. Homeostatic
functions in plants include regulation of water loss and carbon dioxide intake as
well as production of hormones (auxins).
Vocabulary
control center, effector, hormones, hypothalamus, internal feedback mechanism,
negative feedback, pituitary gland, positive feedback, receptor, response, stimulus
(stimuli), target cell
Fundamental Questions
Use the Key Concepts information as well as the information in your Stemscopedia
beginning on page 139 to answer the fundamental questions below.
1. How is homeostasis maintained in plants? Animals?
2. What are the roles of internal feedback mechanisms in maintaining homeostasis?
Analysis
Complete the following in the space provided.
1) Explain what homeostasis is and what it looks like in the human body.
2) Discuss the role of the positive and negative feedback mechanisms.
3) Select an internal feedback mechanism and describe how it effected by an imbalance.