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29 Cards in this Set
- Front
- Back
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What is homeostasis? |
Maintenance of the internal environment in a constant state, within an organism, despite external changes. |
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When can organisms only function? |
If internal conditions such as temperature, pH and water potential are kept in a narrow range |
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Why is it important to maintain the right core body temperature and blood pH? |
Because temperature and pH affect enzyme activity and enzymes control the rate of metabolic activity. |
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Why is important to maintain the right blood glucose concentration? |
Cells need glucose for respiration to produce ATP, and blood glucose concentration also affects the water potential of the blood. |
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What happens to enzyme activity when temperature increases? |
Rate of reaction increases because the molecules have more kinetic energy and so are more likely to collide and form ESCs. |
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What happens to the rate of reaction when the temperature is optimum for enzymes? |
The rate of reaction is at its maximum-v-max |
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What happens if body temp is too low? |
Enzyme activity is reduced, slowing the rate of metabolic reactions. |
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What happens if body temperature is too high? |
Enzymes will denature and metabolic reactions will stop. |
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How is pH calculated? |
The concentration of hydrogen ions (H+) in the environment. |
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On what scale is pH expressed? |
Logarithmic scale. |
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What does a low pH mean in terms of acidity/alkalinity? |
A low pH means more acidic. |
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How do you calculate pH? |
pH=-log10[H+] |
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What happens if blood pH is too acidic or too alkaline? |
enzymes are denatured. |
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What is the optimum pH of pepsin? (found in stomach) |
1.5 |
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What happens if blood glucose concentration is too high? |
Water potential of the blood is reduced to a point where water molecules move out of the cells into the blood by osmosis. This can cause the cells to crenate. |
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What happens when blood glucose concentration is too low? |
Cells aren't able to carry out normal activity because there isn't enough glucose for respiration to provide ATP. |
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What is negative feedback and why is it important? |
It is a process that brings about a reversal of any change of conditions. It ensures that an optimum steady state can be maintained, as the internal environment is returned to its original set of conditions after any change. |
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What happens to a response when the norm is restored? |
It is inhibited. |
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What detects changes in a factor? |
receptors |
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What brings about a response in negative feedback? |
Effetors |
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What controls homeostasis in the body? |
hypothalamus (found in brain) |
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What kind of feedback does homeostasis involve? |
negative feedback |
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Why does homeostasis involve separate negative feedback mechanisms? |
One for increase and one for decrease for each thing being controlled. Also having more than one mechanism gives more control over changes in your internal environment. |
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When would the response theoretically be slower? |
If you had only one negative feedback mechanism, also you would have less control. |
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What is positive feedback? |
The process that increases any change detected by receptors. It does NOT lead to homeostasis. |
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Why would positive feedback be used? |
To rapidly activate processes in the body. |
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Describe an example of positive feedback in the body: |
During the formation of a blood lot, platelets become activated and release a chemical which triggers more platelets to be activtaed. This means platelets can very quickly form a blood clot at injury site. |
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What can occur when there has been a breakdown of homeostatic mechaisms? |
Positive feedback e.g. hypothermia |
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What does this show? |
Negative feedback |
