Homeostasis RaOA

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  • Created by: Alex
  • Created on: 25-05-13 12:54
Homeostasis
Balanced internal environment & tendency of an organism to maintain a steady state in response to changes in the external environment
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Negative feedbck
a physiological response that counteracts/reverses a change in the internal environment - very important in maintaining homeostasis
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Components of negative feedback
A sensor, integrator and effector
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Role of sensor in negative feedback
Detects/ measures change in variable/environment
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Role of integrator in negative feedback
Comparse change with a set point
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Role of effector in negative feedback
Device / process occurs taht restores system by working to bring the change up or down
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Disadvantages of negative feedback
Delay between change and when response initiated. delay in stopping/correcting change - may overshoot set point. may not function in extreme environmets
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Adaptations of negative feedback
Anticipation - predict change befre it occurs (detect outside temp before inside body temp changes), & turn off compensatory response before it overshoots. Acclimitisation-adaptations that alter existing feedback & components - e.g. add fat layer
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temporary change in set point
E.g response to fever & increased temp to fight infection
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Permanent change in set point
e.g. Puberty & increase of sex hormone level
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Cyclical change in set point
E.g. daily (circadian) - body temp overnight, monthly - reproductive, annual - hibernation
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Positive feedback
Rapid change away from the set-point. detected change is enhanced
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Example of positive feedback
Oxytocin causes uterine contractions. oxytocin levels are increases by pressure upon the cervix
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Entantiostasis
change homeostasis by changing a physiological variable to counteract a change in another -maintain and conserve its metabolic & physiological functions in response to variations in unstable environment
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Example of Enantiostasis - blue crabs living in salt or fresh water
low salt ions inhibit O2 binding to haemocyanin. Increases internal ammonia making internal fluids more alkali. Higher alkalinity increases O2 binding to haemocyanin. more O2 available
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Other ways to maintain homeostasis
Regulators, conformers and avoiders
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Regulators in homeostasis
maintain ocnstant internal state - unsing internal mechanisms
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Conformers
Internal state varies with that of the environment, e.g. water snails
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Avoidors
minimalise internal variation by avoiding environmental disturbances e.g. migration
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Basic Cell functions
Cell organisation, Self support, and self - replication
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Self-organisation a basic cell function
Obtain nutrients, eliminate waste, produce energy and synthesis proteins needed for function
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Self-support a basic cell function
Synthesis of proteins needed to maintain shape
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self-replication a basic cell function
Cell division to make more cells
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/specialised cell functions & what they do
Glands - secretion of molecules. Neurones - electrical conductivity, kidney - material exchange
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Whats a tissue
Groups of cells with a similar specialised function
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Whats a organ
2+ types of tissue working together
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Whats an system
2+ organs working together
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whats an organisms
collection of systems working together separate from external environment
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Homeostasis in single cells
Regulate interior via direct contact with exterior
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Homeostasis in multi-cellular
Internal environment & interstitial fluid most remain constant - epithelial cells & systems work to keep everything within narrow limits
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Intrinsic regulation of homeostasis
Regulated by one tissue type/organ. Fast control as occurs locally.
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Example of intrinsic regulation in muscle
Muscle uses O2 and produces CO2. Increase CO2/Decrease O2 causes blood vessels to relax. results in more blood flow to muscle - more O2 in, more CO2 away
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Extrinsic regulation of homeostasis
Regulated bu interactions between different organ systems. control is slower as occurs throught body. e.g. prolonged exercise - diversion of blood from digestive tract to muscle
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Which different systems regulate homeostasis via control systems?
Nervous, Endocrine, Skeleton, Masculature
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Nervous
Rapid coordination in response to external change
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Endocrine system
Slower, longer lasting regulation
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Skeleton
Support other systems and movement
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Musculature
Movement
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Which systems regulate homeostasis directly?
Respiratory, Circulatory, Digestive, Excretory, Integumentary -e.g. skin preventing fluid loss and immune. homeostasis is maintained by the interaction between systems
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Other cards in this set

Card 2

Front

Negative feedbck

Back

a physiological response that counteracts/reverses a change in the internal environment - very important in maintaining homeostasis

Card 3

Front

Components of negative feedback

Back

Preview of the front of card 3

Card 4

Front

Role of sensor in negative feedback

Back

Preview of the front of card 4

Card 5

Front

Role of integrator in negative feedback

Back

Preview of the front of card 5
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