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B5 A) Organisms Responding to Changes in the Environment
B5 A) Organisms Responding to Changes in the Environment
The conditions inside our bodies need to be kept fairly constant to ensure that our body is able to function effectively in response to internal and external changes so that the conditions are optimal for cell/ enzyme activity. Examples of conditions that need to be kept fairly constant are temperature, blood glucose level and water levels. The process of keeping the internal conditions/ environment fairly constant is known as homeostasis. This whole section looks into how our body controls its internal environment to keep the conditions fairly constant.
Homeostasis is important because it allows the body to function effectively. If homeostasis did not occur correctly, it would affect the performance of the body. For example, if the temperature of cells increased to above 37°C or the pH of cells moved away from neutral, it would decrease the rate of reaction of enzymes, thus meaning that substances may not be produced in sufficient quantities, which may affect the performance of the body.
There are many automatic control systems that regulate the conditions in the body. These automatic control systems may involve nervous responses or chemical responses (hormonal responses). All of the automatic response systems have 3 different parts to them, which are:
Homeostasis is important because it allows the body to function effectively. If homeostasis did not occur correctly, it would affect the performance of the body. For example, if the temperature of cells increased to above 37°C or the pH of cells moved away from neutral, it would decrease the rate of reaction of enzymes, thus meaning that substances may not be produced in sufficient quantities, which may affect the performance of the body.
There are many automatic control systems that regulate the conditions in the body. These automatic control systems may involve nervous responses or chemical responses (hormonal responses). All of the automatic response systems have 3 different parts to them, which are:
- Receptors – these detect stimuli, which are changes in the environment
- Coordination centres – these receive and process information from the receptors and coordinate the appropriate response to the stimuli. The coordination centres are the brain, spinal cord and glands (such as the pancreas).
- Effectors – these bring about responses, which returns the conditions of the body back to the optimal level.
Negative Feedback Systems
Automatic control systems use a mechanism known as a negative feedback system to ensure that the internal conditions in the body are constant. A negative feedback system ensures that when the level of something inside the body gets too high or too low, certain responses happen to bring the level back to where it should be/ the optimal level.
The graph below shows the negative feedback system for a variable (temperature).
Automatic control systems use a mechanism known as a negative feedback system to ensure that the internal conditions in the body are constant. A negative feedback system ensures that when the level of something inside the body gets too high or too low, certain responses happen to bring the level back to where it should be/ the optimal level.
The graph below shows the negative feedback system for a variable (temperature).
At the start of the graph, the level of this variable is too high (let’s suppose that the variable is temperature). Receptors in the body notice that the level is too high (the receptors detect a change in stimuli). The receptors send messages to the control centres. The control centres then process the information from the receptors and organise a response. Messages are then sent from the control centres to the effectors, which produces a response that brings the level of a particular variable back down to the optimal level (for our example, temperature will come back down to the optimal level).
Whenever the effectors are told to produce a response, they will continue to produce the response until they are no longer stimulated (told to produce the response). This may cause the level of the variable to become too low.
If the level of this variable becomes too low, it will be detected by receptors who will send messages to the control centres. The control centres then process the information from the receptors and produce a response. Messages are then sent from the control centres to the effectors, which produces a response that increases the level of the variable back to the optimal level (for our example, temperature increases back to the optimal temperature).
Negative feedback systems continuously occur in our bodies to ensure that the internal conditions of the body remain fairly constant/ at the optimal level for enzymes and cells to function.
Whenever the effectors are told to produce a response, they will continue to produce the response until they are no longer stimulated (told to produce the response). This may cause the level of the variable to become too low.
If the level of this variable becomes too low, it will be detected by receptors who will send messages to the control centres. The control centres then process the information from the receptors and produce a response. Messages are then sent from the control centres to the effectors, which produces a response that increases the level of the variable back to the optimal level (for our example, temperature increases back to the optimal temperature).
Negative feedback systems continuously occur in our bodies to ensure that the internal conditions of the body remain fairly constant/ at the optimal level for enzymes and cells to function.