Ch16 Principles Flashcards
1
Q
Homeostasis
A
- maintenance of constant internal environment
- within restricted limits
- return to optimum point
2
Q
4 Examples of homeostasis
A
- blood pH
- thermoregulation
- water potential
- blood glucose concentration
3
Q
Negative feedback mechanism
A
- receptor detects change from set level
- effector initiates corrective mechanism
- returns to optimum point
4
Q
Positive feedback
A
- receptor detects change from set level
- effector initiates corrective mechanisms- stays on
- deviates further from optimum point
e.g. Na+ in action potential
hypothermia
5
Q
thermoregulation- high temperature
A
- receptors in hypothalamus detect increase in temperature of blood
- heat loss centre stimulated
- vasodilation
- arterioles in skin surface dilate
- more flood flows to skin surface
- heat loss by radiation
- heat loss by evaporation of sweat
- reduced metabolic rate
6
Q
thermoregulation- low temperature
A
- receptors in hypothalamus detect decrease in temperature of blood
- heat gain centre stimulated
- vasoconstriction
- arterioles in skin surface constrict
- less blood flows to skin surface
- reduced heat loss by radiation
- decreased sweating
- increased metabolic rate- respiration, shivering
7
Q
Enzymes and body temperature
A
- Body temp (37°C) is optimum temp for enzymes
- excess heat denatures enzymes and alters tertiary structure
- active site not complementary
- substrate cannot bind to form enzyme-substrate complexes
- reduces kinetic energy of molecules
- fewer collisions and enzyme-substratecomplexes formed
8
Q
Advantage of set body temperature
A
- Optimum temperature for enzymes
- Optimum energy release for movement
9
Q
Endotherms
A
derive heat energy from metabolic activities
10
Q
Ectotherms
A
- obtain heat from external environment
- body temperature fluctuates with exposure to sun
- no physiological cooling system
