Regulation and disruption

the maintenance of a constant, optimal internal environment despite changes in the external environment

controlled by the nervous and endocrine system; the nervous system sends electrical impulses, endocrine system secretes hormones to counteract the stimulus

The response reduces or eliminates the stimulus causing the effect Eg. Dropping body temperature

The response intensifies the stimulus

Fluctuations around the set point, controlled by homeostasis

The optimum level around which levels fluctuate

Thermoreceptors are found within the skin and mucous membrane (peripheral thermoreceptors) and in the hypothalamus and vital organs (central thermoreceptors)

provide info about the external environment: cold and hot receptors

detect changes in internal temperatures

Caused by dehydration and continuous vasodilation, causing low blood pressure. Person may collapse, but internal body temperature remains normal

Caused by high temperatures and humidity – body temperature increases past 42˚C. Causes regulatory mechanisms to cease

Core temperature falling below 33˚C; causes metabolic rate to slow, decreased heat production

Conduction, radiation, evaporation, convection

found inside the cells

outside the cells, including blood plasma

between cells (interstitial fluid)

fluid within the blood stream

any fluid found within the lymph vessels

Lymphatic obstruction causing excess extracellular fluid to collect outside the lymph vessels

Water loss exceeds water intake through vomiting, sweating, or diarrhoea Severe thirst, low blood pressure, dizziness, headache

Dilation of bodily fluids, leading to cells taking in more water by osmosis

Inhibits ADH production – decreased water reabsorption in the collecting duct

produced by the beta cells in the pancreas, and decreases blood glucose levels

Accelerates the transport of glucose from blood to cells, conversion of glucose to glycogen, stimulates conversion of glucose into adipose tissue, increase in protein synthesis