What conditions are maintained within cells to ensure correct function?
A suitable pH, a suitable temperature, am aqueous environment that keeps substrates and products in solution, freedom from toxins and excess inhibitors.
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What is cell signalling?
The way in which cells communicate with eachother. Two main communication system. Neuronal communication: interconnected network of neurones that signal to each other across synapse junctions, rapid responses. Hormonal system: uses blood to transport
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What is homeostasis?
Maintaining a constant internal environment despite changes in external and internal factors.
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What aspects in the body is maintained by homeostasis?
Body temperature, blood glucose concentration, blood salt concentration, water potential of blood, blood pressure, carbon dioxide concentration
Cells/sensory nerve endings that respond to a stimulus in internal/external environment of an organism and can create action potentials. e.g. temperature receptors on surface of skin
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What are effectors?
A cell, tissue or organ that brings about a response.
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What is negative feedback?
The mechanism that reverses a change, bringing back system to optimum. A change to internal environment detected, change signalled to other cells, effective response reverses change in conditions. E.g. temperature control
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What is positive feedback?
Mechanism that increases a change, taking system further away from optimum. E.g. uterine contraction that stretches cervix in child birth.
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What is an ectotherm?
An organism that relies on external sources of heat to maintain body temperature
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How do ectotherms maintain body temperatures when they get too cold?
They try to absrob more heat from environment. Move to sunny area (basking), lies on warm surface (rocks) and expose a larger surface area to to the sun
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How do ectotherms maintain body temperature when they get too hot?
Try to avoid gaining more heat from the environment and try to increase heat loss. They may move out of the sun and move underground, reduce body surface area exposed to the sun
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What are the advantages of ectothermy?
Less food used for respiration and more energy amnd nutrients can be converted to growth. They need to find food less and can survive long periods without food
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What are the disadvantages of ectothermy?
Less active in cooler temperatures. Greater risk of predation at low temperatures while they are cold and unable to escape. Cannot take advantage of food available when it's cold.
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What is an endotherm?
An organism taht uses heat from metabolic activity to maintain body temperature.
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What is the role of skin in temperature regulation?
When too hot, sweat glands secrete sweat that cools skin when evaporated, hairs lie flat to reduce insulation and vasodilation of arterioles increases heat loss from blood. When too cold; less sweat secreted, hairs stand erect and vasoconstriction
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What is the role of the liver in temperature regulation?
When too hot; less respiration takes place so less heat is released. When too cold; increased repiration in hepatocytes means more energy from food is converted to heat
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What is the role of skeletal muscles in temperature regulation?
When too hot; fewer contractions mean less heat is released. When too cold; spontaneous muscle contraction (shivering) releases heat
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What is the role of blood vessels in temperature regulation?
When too hot; dilation to direct blood to extremities so that more heat can be lost. When too cold; constriction to limit blood flow to extremities, so that blood is not cooled as much- this can lead to frostbite in extreme conditions.
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What are the advantages of endothermy?
Endotherms can; maintain a farily constant body temperaure whatever the external temperature. Remain active even when external temperatures are low (take advantage of ecothermic prey), inhabit colder parts of the planet.
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What are the disadvantages of endothermy?
Use significant part of energy intake to maintain body temperature in the cold. Need more food, less nutrients and energy used for growth, may overheat in hot temperatures
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What is the hypothalamus?
Part of brain taht coordinates homeostatic responses. Temperature regulators in hypothalamus detect temperature change of blood then hypothalamus releases impulses which reverses change.
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Other cards in this set
Card 2
Front
What is cell signalling?
Back
The way in which cells communicate with eachother. Two main communication system. Neuronal communication: interconnected network of neurones that signal to each other across synapse junctions, rapid responses. Hormonal system: uses blood to transport
Card 3
Front
What is homeostasis?
Back
Card 4
Front
What aspects in the body is maintained by homeostasis?
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