Give the sequence of control mechansims in a feedback loop
Input > Receptor > Control unit > Effector > Output > Set point
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What are the two types of feedback mechanism?
Positive and negative feedback
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How does negative feedback work?
When a change occurs in a system, the change automatically causes a corrective mechanism to start, which reverses the original change and brings the system back to its set point
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How does positive feedback work?
It occurs when the feedback causes the corrective mechanism to remain turned on and results in the system to deviate even more from the set point
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What is the set point?
At point at which the system works best- it can fluctuate
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What is thefunction of a receptor in a feedback mechanism?
It detects a deviation from the optimum (set) point and informs the control unit
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What is the function of a control unit in a feedback mechanism?
It coordinates information from receptors and sends instructions to the appropiate effector
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What is the function of an effector in a feedback mechanism?
A muscle or gland which brings about changes to retun the system to the set point. It brings about an output.
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Why is homeostasis important in enzyme andd other protein activity?
Enzymes and proteins are affected by changes in temperature and pH and may even cease to function too far from their optimum values, hence homeostasis enables a regular internal environment of optimum temperatures and pHs to be maintained
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How does homeostasis prevent cells changing size?
By maintaining a regular blood glucose level hence constant water potential
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How does homeostasis provide better survival chances?
Organsims with the ability to maintain a constant internal environment can withstand changes in the external environment a lot better and adapt to new environments
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What is an endotherm?
Organisms such as mammals and birds which maintain a constant body temperature higher than the external environment via homeostatic mechanisms
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What are ectotherms?
Organisms that maintain their internal body temperature by altering their external conditions
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Give an example of how ectotherms regulate their body temperature
By moving between the sun and shade to warm up or cool down
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List four ways in which organisms can lose heat in a warm environment
Arterioles leading to blood capillaries near the skin's surface dilate which allows more blood to flow through the shunt vessel into the capillaries near the skin to transfer heat to the environment through radiation
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How does sweating decrease internal body temperature?
Sweat glands are stimulated to release sweat which can evaporate from the body
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How does lowering of hairs allow the body to cool down?
As hair erector muscles relax hence lowering the hairs, this stops an insulating layer of air being trapped next to the skin's surface
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What is the basal metabolic rate?
The rate of metabolism at rest
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Why would a decreased basal metabolic rate decrease body temperature?
Any energy not used to form ATP will be lost as heat energy, the less energy needed for energy the more that is lost as heat
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Give five ways how heat energy can be conserved in a cold environment
Arterioles leading to capillaries near the skin's surface are constricted hence less blood flows through the shunt vessel into the capillaries near the skin and less heat is transferred to the surroundings by radiation
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What does raising of hairs create?
An insulating layer of air to be trapped on the skin's surface
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How does an increased basal metablic rate increase body temperature?
By increasing basal metabolic rate, the production of hormones that control metabolism will increase so the rate of respiration will too hence more heat is produced
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How does shivering keep the body warm?
A rapid contraction and relaxation of muscles generates heat
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How is temperature of the blood monitored?
By the thermoregulatory centre in the hypothalamus
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What type of nervous system is the thermoregulatory centre part of?
Autonomic nervous system
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Other cards in this set
Card 2
Front
Give the sequence of control mechansims in a feedback loop
Back
Input > Receptor > Control unit > Effector > Output > Set point
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