[16.1] principles of homeostasis Flashcards
1
Q
what is homeostasis?
A
maintenance of a constant internal environment
2
Q
what factors are maintained by homeostasis? (6)
A
- body temperature
- blood glucose concentration
- blood ion concentration
- blood water potential
- urea concentration (waste)
- pH
3
Q
what is the significance of an optimum point in homeostasis?
A
- there are continuous fluctuations brought about by variations in internal and external conditions
- these changes occur around an optimum point
- homeostasis is the ability to return to the optimum point
- you want to avoid large flucuations above and below the norm level
4
Q
why is homeostasis essential for the proper functioning of organisms? (3)
A
- enzymes
- water potential
- external environments
5
Q
why is homeostasis important for enzymes?
A
- enzymes are sensitive to changes in pH and temperature
- any changes to these factors reduces the rate of reaction of enzymes
- they may be prevented from working as they are denatured
- maintaining a fairly constant internal environment means that reactions take place at a suitable rate
6
Q
why is homeostasis important for water potential?
A
- changes to the water potential of the blood and tissue fluid cause cells to shrink and expand, even to bursting point, due to water leaving or entering by osmosis
- this means cells cannot operate normally
- maintaining a constant blood gluose concentration is essential to maintain a constant water potential
- constant bloood glucose concentration also ensures a reliable source of glucose for respiration by cells
7
Q
why is homeostasis important for external environments?
A
- organisms with the ability to maintain a constant internal environment are more independent of changes in the external environment
- they may have a wider geographical range so a greater chance of finding food, shelter etc.
8
Q
what are the stages involved in the control of a self-regulating system?
A
- optimum point
- receptor
- coordinator
- effector
- feedback mechanism
8
Q
control mechanisms: optimum point
A
- point at which the system operates best
- monitored by a receptor
9
Q
control mechanisms: receptor
A
- detects any deviation from the optimum point (stimulus)
- informs the coordinator
10
Q
control mechanisms: coordinator
A
- coordinates information from receptors
- sends instructions to an appropriate effector
11
Q
control mechanisms: effector
A
- muscle or gland
- brings about changes needed to return the system to an optimum point
- return to normality creates a feedback mechanism
12
Q
what is a feedback mechanism?
A
when a receptor responds to a stimulus created by the change to the system brought about by the effector
