Term
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Definition
| The desired value for regulsted variables |
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Definition
Are activated and send signals to a controller if a regulated variable moves out of desirable range
Monitor and respond to changes (stimuli) in the environment - send messages to the control centre
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Term
| Integrating centre/ Control centre |
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Definition
Evaluates information coming from the centre and initiates a response that is designed to bring the regulated variable back into the desirable range
Determines the level (set point) at which variable is to be maintained
Sends messages to the Effector |
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Definition
| Nerves that carry sensory information from receptors to an integrating centre located within the central nervous system Receives signal from sensor, and relays signal to integrating centre |
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Definition
Involves nerves that carry motor commands from the integrating centre to the various effector tissues such as muscles and glands. The output signal is initiated by the integrating centre & sent to the effector. |
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Term
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Definition
| A homeostatic feedback loop designed to keep the system at or near a set point. A reaction in which the system responds in such a way as to reverse the direction of change. Since this tends to keep things constant, it allows the maintenance of homeostasis. For instance, when the concentration of carbon dioxide in the human body increases, the lungs are signalled to increase their respiratory rate and expel more carbon dioxide. Thermoregulation is another example of _negative__ feedback. When body temperature rises (or falls), receptors in the skin and the hypothalamus sense a change, triggering a command from the brain. This command, in turn, affects the correct response, in this case a decrease in body temperature. |
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Definition
| A feedback loop in which the response reinforces the stimulus, triggering a vicious cycle of ever-increasing response a response is to amplify the change in the variable. This has a destabilizing effect, so does not result in homeostasis. __Positive___ Feedback is less common in naturally occurring systems than negative feedback, but it has its applications. For example during childbirth, the secretion of oxytocin enhances uterine contractions leading to childbirth. |
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Definition
| Are muscles or glands under the control of an integrating centre whose response seeks to restore or maintain homeostasis, the cell or tissue that carries out the appropriate response to bring the situation back to within normal limits. |
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Definition
| Consists of the Extra-cellular fluid compartment |
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Definition
The internal environment of vertebrates, consisting of the fluid filling the spaces between cells. |
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Definition
| The internal fluid of the cell. |
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Definition
The part of the total body fluid that is within the vascular system |
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Term
| Interstitial fluid compartment |
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Definition
| Interstitial fluid (or tissue fluid) is a solution that bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes plasma and transcellular fluid. The interstitial fluid is found in the interstitial spaces, also known as the tissue spaces |
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Term
| Sequence of a neural homeostatic loop |
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Definition
Stimulus, receptor, afferent pathway, integrating center, efferent pathway, effector |
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Definition
ECF =
Interstitial fluid
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Blood (or plasma) |
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Term
Nervous and endocrine systems
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Definition
| Allow different body parts to communicate in order to maintain homeostasis |
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Term
| When does homeostasis maintain optimal cell function? |
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Definition
- When core body temp is maintained
- When the concentration of dissolved substances are maintained
- When pressure is maintained - gases/osmosis/hydrostatic
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Term
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Definition
Essentially the skin - lowest temperature
Fluctuates wildly between 20 and 40 degrees
To maintain core stability
•Temperature closer to skin
•36.6o-37.0oC (97.9o-98.6oF) |
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Term
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Definition
Temperature of organs in cranial, thoracic andabdominal cavities
Highest temp - precisely regulated
In a narrow range
Rectum best indicator of core
•37.2o-37.6oC (99.0o-99.7oF) |
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Term
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Definition
In dynamic equilibrium as a result of balance between heat gain and heat loss
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Term
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Definition
Infra red radiation
Heat loss via infa red waves from the body, a radiator
Gain heat from sun via radiation
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Definition
Direct transfer of energy through physical contact
From warmer to cooler - eg. warming a chair |
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Definition
Heat loss through air around the human body
Transfer of heat to the air which rises and is replaced by cooler air
A fan/ the wind increases convection |
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Definition
Energy change in water molecule from liquid to vapour
Heat loss as it is used to evaporate water eg. in the skin/lungs |
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Term
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Definition
Integrative centre which establishes a temperature set point and receives feedback information
Heat loss centre
Heat gain centre
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Term
| Peripheral thermoreceptors |
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Definition
Found in the skin
Detect and monitor the temperature of the internal/external environment |
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Term
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Definition
Measure the temperature of the core
Most important located in hypothalamus |
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Term
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Definition
1. Activates heat gain mechanisms
- constriction of dermal arterioles - decreases blood flow to the skin
- shivering thermogenesis
- Non shivering thermogenesis
- Behavioural: add clothing
2. Inhibits heat loss centre
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Term
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Definition
- Activates heat loss mechanisms
- Dilation of dermal arterioles - increases blood flow to skin
- Sweating
- Increased respiration through the mouth
- Behavioural - remove clothing
- Inhibits heat promoting centre
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Term
Thermoregulation - control of body temperature
Negative feedback system to counteract heat gain |
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Definition
Stimulus - increased temp when exercising or in hot surroundings
Thermostat in the hypothalamus activates heat cooling mechanisms
Skin dermal arterioles dilate - fill with blood
Heat radiates from skin surface
Sweat glands activated - increased cooling by evapouration
Body temperature decreases
Thermostat shuts off cooling mechanisms
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Term
Thermoregulation - control of body temperature
Negative feedback loop to increase body temperature |
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Definition
Stimulus - decreased body temperature due to cold surroundings
Thermostat in the hypothalamus activates warming mechanisms
Dermal arterioles constrict - blood diverted away from skin to major organs and deeper tissues - heat loss from skin surface reduced
Skeletal muscles are activated
Shivering generates more heat
Body temperature increases
Thermostat turns off warming mechanisms
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Term
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Definition
Fever accompanies infections
White body cells secrete pyrogens
Body temperature set point increases
Fever enhances immune response
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Term
| What is the role of the afferent and efferent pathways in homeostatic regulation? |
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Definition
Sensory vs motor nerves
Afferent nerves convey messages to the control/integrating centre
Efferent nerves from said centre to effectors
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Term
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Definition
Cell metabolism
Thyroxin/adrenalin
Shivering |
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Term
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Definition
Vasoconstriction
Change body posture - hunch over |
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Term
| Non-shivering thermogenesis is a mechanism of heat production in infants. Why is it not physiologically significant in adults? |
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Definition
Infants are unable to shiver therefore generate non-shivering thermogenesis due to presence of brown fat
Adults can shiver - effective |
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Term
| Normal range for core body temperature |
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Definition
| 35.6 - 37.8 degrees celsius |
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