Student Sample Christopher Duncan

What is Homeostasis? 1.homeo=same; stasis=standing 2.Homeostasis is the term we use to describe the constant state of the internal environment. 3.Homeostasis is a state of balance in the body. 4.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 The body must have good internal communication, using the endocrine and nervous systems, to maintain homeostasis. Nervous system and/or endocrine system responds

Negative 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.

Thermoregulation (must be viewed in slide show to use tabs)

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

Hormone Secretion Regulation Sensing and signaling: a biological need is sensed, the endocrine system sends out a signal to a target cell whose action addresses the biological need. Key features of this stimulus response system are: – · receipt of stimulus – · synthesis and secretion of hormone – · delivery of hormone to target cell – · evoking target cell response – · degradation of hormone

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, eg.heatexchange/ eg.heatexchange/ A.D.A.M. Inc., Multimedia Encyclopedia, , retrieved on March 14, , Johnson, Michael. Human Biology: Concepts and Current Issues (4th Edition) (The Human Biology Place Series). San Francisco: Benjamin Cummings, "Physiological Homeostasis." Biology Online. 1 Jan Mar online.org/4/1_physiological_homeostasis.htmhttp:// online.org/4/1_physiological_homeostasis.htm