Homeostasis+text

Homeostasis+text - Maintaining the Internal Environment...

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1 Maintaining the Internal Environment Chapter 49
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2 Need to Maintain Homeostasis Homeostasis may be defined as dynamic constancy of the internal environment. Negative feedback loops The vertebrate body must have sensors to measure conditions of the internal environment. information relayed to integrating center When a deviation occurs, the integrating center sends a message to increase or decrease the activity of particular effectors .
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3 Need to Maintain Homeostasis Regulating body temperature Hypothalamus responds to increased body temperature by promoting the dissipation of heat through sweating, dilation of blood vessels, and other mechanisms. Coordinates a different set of responses such as shivering and blood vessel constriction for decreased body temperature.
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4 Need to Maintain Homeostasis Regulating blood glucose Glucose levels are constantly monitored by the islets of Langerhans in the pancreas. When levels increase, the islets secrete insulin which stimulate blood glucose uptake. In this case, the islets are the sensor and the integrating center.
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5 Antagonistic Effectors and Positive Feedback Antagonistic effectors Increasing activity of one effector is accompanied by decreasing activity of an antagonistic effector. Positive feedback loops feedback loops that accentuate a disturbance Perturbations cause the effector to drive the value of the controlled variable even farther from the set point.
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6 Osmolality and Osmotic Balance Osmolality and osmotic pressure Because the total solute concentration of a solution determines its osmotic behavior, the total moles of solute per kilogram is expressed as osmolality of the solution. hypoosmotic , hyperosmotic , isoosmotic Osmotic pressure of a solution is a measure of its tendency to take in water by osmosis. hypertonic , hypotonic , isotonic
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7 Osmolality and Osmotic Balance Osmoconformers and osmoregulators osmoconformers - Osmolality of body fluid is same as that of surroundings. no osmotic gradient
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Homeostasis+text - Maintaining the Internal Environment...

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