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13 Cards in this Set
- Front
- Back
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Definition of Homeostasis
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An energy-dependent condition where a system maintains a steady state of its internal environment through coordinated responses of its parts in response to stimuli that disturb its normal condition or function
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Relationship btwn External & Internal Environments
• position with respect to the body and cells • description using intra and extracellular fluid |
The External environment is outside of our body while the internal environment is the extracellular fluid bathing all our tissues and cells. The intracellular fluid is within cells. The ECF and ICF are in communication with each other.
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The 3 body fluid compartments and general relative high/low descriptions for ionic and protein concentrations
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Blood plasma: [Na+] = H, [Cl-] = H, [K+] = Low, [Protein] = Low.
ECF: [Na+] = H, [Cl-] = H, [K+] = Low, [Protein] =zero. ICF: [Na+] = Low, [Cl-] = Low, [K+] = High, [Protein] = High |
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body fluid compartments stem
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body fluid compartments answer
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4 ex of homeostatic mech to control
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temp, pH, oxygen levels, CO2 levels, BP
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Concept of Negative Feedback
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When the value of the controlled variable has gone above or below its normal set-point, its goal is to bring it to normal
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5 terms attributed to negative feedback
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Controlled variable, Set Point, Sensor, Comparator, Effector
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Define: Controlled variable, Set Point, Sensor, Comparator, Effector
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Controlled Variable: The physiological parameter being controlled
Set Point: The ideal value of the controlled variable as influenced by genetics and environment Sensor: Usually a receptor, it detects changes in the controlled variable Comparator: The integration center of the of the negative feedback response, it analyzes the data from the sensor, compares it to the set-point and if the two are incongruent, the comparator sends a signal Effectors: Receive the signal from the comparator. Appearing in the form of nerve pathways, cells or tissues, they carry out the response, with the goal of returning the control variable back to normal value/set point. |
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Ex of when deviation in set points might occur (4)
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Over a 24hr period: K+ excretion is > during the day, circadian rhythms of hormones
Environmental changes: living at high altitudes causes acclimitization to adjust for low pO2 levels Pathological changes: BP set point may steadily increase due to atheromatous plaques in vessels. BP control mechs continue to operte around these new set points Protective response: The set point for iron decreases significantly during an infection to deprive the bacteria of the micronutrient |
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Purpose for redundancy in homeostatic mechs
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As a parameter/controlled variable becomes increasingly vital, more homeostatic mechanisms exists to ensure it can be controlled if one mech fails
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Purpose for heirarchy of importance in homeostatic mechs
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The set points of some variables may be altered to maintain oher controlled variable which are more important.
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Concept of Positive Feedback
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After the comparitor recognizes the error btwn the data from the sensor and the set point, it intensifiesthe error and moves the value of the controlled variable further away from he set point
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Concept of feed forward regulation
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Your body in preparation, it anticipates a change of the controlled variable before it happens
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