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The tendency to maintain the relative consistency of certain variables, even in the face of significant environmental changes.
Homestasis
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What achieves homeostatic control of our extracellular fluid characteristics?
Drinking and eating
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Homeostasis maintains a constant what, which includes temperature, blood, gases, glucose, and socium
Internal environment
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Characteristic to be regulated, body fluids.
System variable
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Optimal value system of the system variable, optimal fluid level.
Set point
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Monitors the value of the system variable, mechaism that signals when the system variable deviates from its set point
Detector
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The mechanism that restores the system variable to its set point
Correctional mechanism
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A process whereby the effect produced by an action serves to terminate the action
Negative feedback
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Eating and drinking, regulatory mechaism to restore lost fluid and nutrients
Ingestive behavior
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A brain mechanism that causes cessation of hunger or thirst
Satiety mechanism
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About what percentage of our body is made up of fluid?
65%
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How many days can we go without water and survive?
3-5 days
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Sensation of thirst does not occur until we are...
mildly dehyrdrated (1-3% loss of body weight due to fluid loss)
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Increased osmotic pressure of the interstitial fluid relative to the intracellular fluid leads to dehydration
Osmometric thirst
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These are specialized multipolar neurons that are rich around the third ventricle
Osmoreceptors
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In osmometric thirst, as water leaves the receptor cell, what happens to axon activity?
It increases
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What is being monitored with osmometric thirst?
Central nervous system
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With this type of thirst, volume of blood plasma decreases
Volumetric thirst
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The kidneys are involved in what type of thirst?
Volumetric
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The release of aldosterone leads to what craving?
Salt
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This tries to retain as much water in the body as possible during volumetric thirst...
Vasopressin
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What keeps our cells alive?
Oxygen and fule
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What are the short term reservoirs of fuel in the body?
Carbs
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What are the long term storage reservoirs in the body?
Fats
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What are the two phases of metabolism?
Fasting and absorptive phase
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In this phase, nutrients are not available from the digestive system. Fuel used first in the short term reserves. Once those are used, goes after the long term reserves.
Fasting phase
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In this phase, nutrients are absorbed from the digestive tract, which is full.
Absorptive phase
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Muscle and liver cells are filled with complex involuble carbs (short term reserves) called what?
Glycogen
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What kind of tissue is filled with fats?
Adipose tissue
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Complex molecules that cobine glycerol with 3 fatty acids
Triglycerides
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Fatty acids are broken down by most cells in the body except where?
The brain
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This is used for fuel when insulin levels drop significantly and the drop is sustained.
Triglycerides
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The brain uses what as an energy source?
Glucose
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This is caused by drop in blood glucose levels or drugs that inhibit glucose metabolism. It stimulates eating.
Glucoprivation
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Afferent fibers in this glucoreceptor respond to blood glucose levels and lipoprivation
Glucoreceptors
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What are two main glucoreceptors?
Liver and the brain
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Drop in fatty acids available to cells that is usually caused by drugs.
Liporivation
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If we had very efficient metabolisms, what would we look like?
Very large
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How many people in the US are overweight?
34 million
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