What is Homeostasis? homeo = same; stasis = standing
Homeostasis is the term we use to describe the constant state of
the internal environment. Homeostasis is a state of balance in the
body. The processes and activities that help to maintain
homeostasis are referred to as homeostatic mechanisms
Slide 4
Neural and endocrine control Sensory receptors detect change in
a monitored variable The body must have good internal
communication, using the endocrine and nervous systems, to maintain
homeostasis. Nervous system and/or endocrine system responds
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Feedback Loop All homeostatic mechanisms use negative feedback
to maintain a constant value (called the set point). Negative
feedback never maintains perfectly, but constantly fluctuates about
the set point. An efficient homeostatic system minimizes the size
of the fluctuations.
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Thermoregulation (click on the tabs below)
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What happens when the body becomes imbalanced? Variations in
hormone concentration and target cell sensitivity have noticeable
effects on the body Hypo secretion inadequate hormone release tumor
or lesion destroys gland head trauma affects pituitary glands
ability to secrete ADH diabetes insipidus = chronic polyuria Hyper
secretion excessive hormone release tumors or autoimmune disorder
toxic goiter (graves disease) antibodies mimic effect of TSH on the
thyroid
Slide 8
The Bodys Stress Reaction Stress = Hormone Secretion=
Unbalanced System
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What are the major glands and hormones involved in Homeostasis?
Hypothalamus (Master Gland) Thyrotropin-releasing hormone Growth
Hormone Gonad releasing hormone Corticotropin-releasing
hormone
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Major Gland and Hormones Pancreas Insulin Glucagon Somatostatin
Amylin
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Major Glands and Hormones Thyroid Gland Thyroxine
Triiodothyronine Calcitonin
Slide 12
Summary Homeostasis is the process by which the human body
maintains comparative steadiness of internal conditions.
Homeostasis is retained through negative feedback loops.
Homeostasis is achieved through neural and endocrine
processes.
Slide 13
Works Cited Teachers' Domain, Blood Flow and Thermoregulation,
published August 9, 2007, retrieved on March 15, 2009,
http://www.teachersdomain.org/resource/lsps07.sci.life.reg.h
eatexchange/
http://www.teachersdomain.org/resource/lsps07.sci.life.reg.h
eatexchange/ A.D.A.M. Inc., Multimedia Encyclopedia, 1997-2008,
retrieved on March 14, 2009-03-15,
http://www.adam.com/multimediaencyclopedia.aspx
http://www.adam.com/multimediaencyclopedia.aspx Johnson, Michael.
Human Biology: Concepts and Current Issues (4th Edition) (The Human
Biology Place Series). San Francisco: Benjamin Cummings, 2007.
"Physiological Homeostasis." Biology Online. 1 Jan. 2000. 13 Mar.
2009. http://www.biology-
online.org/4/1_physiological_homeostasis.htmhttp://www.biology-
online.org/4/1_physiological_homeostasis.htm
