9.1 Homeostasis Flashcards
Homeostasis definition
Maintaining of internal conditions of the body at a relatively constant dynamic equilibrium with restricted limits
Why pH is controlled
To ensure optimum enzyme activity
Why temperature is controlled
To ensure optimum enzyme activity
By preventing denaturing
Why water potential is controlled
Prevent cell crenation or lysis
To control volume of water in tissue fluid and cells
Which ensures a constant cell size
Control mechanism
1) optimum point
Point at which the system operates best
Control mechanism
2) receptor
Measures any deviation from optimum point and informs co ordinator
Control mechanism
3) co ordinator
Co ordinates instructions and sends them to appropriate effector
Control mechanism
4) effector
Brings about change to return the system to optimum point
Order of control mechanism
1) optimum point
2) receptor
3) co ordinator
4) effector
Negative feedback
Self regulating mechanism resulting in corrective measures for any change in system returning it to normal
2 mechanism
1) increase
2) decrease
For greater control
Negative feedback in control of blood plasma
Low water potential detected by hypothalamus
Less ADH released
Collecting duct is less permeable
Less water is reabsorbed
Why large animals consume more oxygen per mass
Ectotherms
Loose more heat
By respiration
Low surface area to body ratio
