Unit+4+Homeostasis

Homeostasis

Tahrik Rodriques January 6 2013

=Homeostasis= __Maintaining Internal Balance 9.1__

Homeostasis is the dynamic process where internal physical and chemical conditions are maintained within an optimal range promoting proper cellular function.

Body fluids and conditions that need to be monitored and maintained;
 * Internal temperature
 * blood glucose levels
 * blood pH
 * hormone levels


 * Internal environment:** the extracellular fluid surrounding our cells and tissues, it also makes up the plasma portion of the blood
 * **Interstitial fluid:** the fluid surrounding the body cells / fills the spaces between our cells and tissues

=Organ Systems Involved in Homeostasis= **Muscular System**: skeletal, cardiac, smooth muscle **Integumentary System**: skin, sweat glands, hair, nails Out of all the systems involved, the endocrine and nervous systems are the most important
 * Nervous System**: brain, spinal chord, peripheral nerves, sensory organs
 * Endocrine System**: pituitary gland, thyroid, adrenal, pancreas
 * Excretory System**: kidneys, bladder, ureter, urethra
 * Reproductive System**: female organs (ovaries, oviducts, uterus, vagina, mammary glands), male organs (testes, sperm ducts, accessory glands, penis)

__Feedback Mechanisms 9.2__

Two types of feedback mechanisms; Labour contractions during child birth are good examples of positive feedback loops
 * **Positive**: the response of a system that acts to increase the effect of any changes made to the system
 * enhance the effect of a change in the internal or external environment
 * usually does not result in homeostasis
 * 1) uterine contractions (stimulus) detected by the pituitary gland release oxytocin
 * 2) as the amount of oxytocin being released increases, uterine contractions increase, in turn more oxytocin is released and so on


 * **Negative**: the response of a system that acts to maintain equilibrium by compensating for any changes made to the system
 * responses to negative feedback loops may be physiological or behavioral



stimulus: environmental change sensor: the element of a feedback system detecting changes in environment integrator/control: compares present conditions to ideal conditions effector: it acts to return the system to its optimal state

Another example of a negative feedback loop is a thermostat.

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