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Student Sample. Christopher Duncan. 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.
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Student Sample Christopher Duncan
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
Neural and endocrine control Sensory receptors detect change in a monitored variable Nervous system and/or endocrine system responds • The body must have good internal communication, using the endocrine and nervous systems, to maintain homeostasis.
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.
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 gland’s 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
The Body’s Stress Reaction Stress = Hormone Secretion= Unbalanced System
What are the major glands and hormones involved in Homeostasis? Hypothalamus (Master Gland) • Thyrotropin-releasing hormone • Growth Hormone • Gonad releasing hormone • Corticotropin-releasing hormone
Major Gland and Hormones Pancreas • Insulin • Glucagon • Somatostatin • Amylin
Major Glands and Hormones Thyroid Gland • Thyroxine • Triiodothyronine • Calcitonin
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.
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.heatexchange/ • A.D.A.M. Inc., Multimedia Encyclopedia, 1997-2008, retrieved on March 14, 2009-03-15, 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.htm