27.1 principles of homeostasis Flashcards
1
Q
homeostasis
A
- homeostasis is the maintenance of a constant internal environment in organisms
- ensures that cells of the body are in an environment that meets their needs and allows them to function normally despite external changes
2
Q
conditions should be maintained by homeostasis
A
- temperature
- pH levels
- water potential
- blood composition
3
Q
why is control of internal temperature and pH levels important
A
- enzymes that control the biochemical reactions
- and channel proteins found on cell surface membrane of cells are sensitive to pH levels and temperature
- any deviation from the optimum conditions will impair their activity
4
Q
what effect on enzyme activity does an increase in temperature has
A
- increase in temperature, increases the kinetic energy
- increase in kinetic energy, will increase the number of collisions
- more enzyme-substrate complexes formed at a fast rate
- however, a rise beyond optimum will cause the hydrogen, disulphide bridge and other internactions to break
- this will lead to a change in the shape of enzyme and its active site
- the enzyme denatures eventually
- enzyme-substrate can no longer be formed
5
Q
what effect on enzyme activity does a decrease in temperature has
A
- decrease in temperature, decreases the kinetic energy
- number of collisions decreases
- enzyme-substrate complexes formed but at a very slow rate
6
Q
what effect on enzyme activity does pH level have
A
- pH level at optimum will increase rate of enzyme activity
- enzyme-substrate complexes formed at a faster rate
- increase of pH beyond optimum will break bonds holding the tertiary structure
- shape and active site of enzyme changes
- enzyme denatures
- enzyme-substrate complexes not formed
7
Q
what effect on cells does water potential of the blood and tissue fluid have
A
- may cause cells to either shrink or swell (may even burst)
- this is because of movement of water in and out via osmosis
8
Q
stages of control mechanisms
A
- set point
- receptor
- controller
- effector
- feedback loop
9
Q
what is a set point
A
- the desired level or norm, at which the system operates
10
Q
what is a receptor
A
- anything that detects any deviation from the set point
11
Q
what is a controller
A
- coordinates information from various receptors and sends them to an appropriate effector
12
Q
what is an effector
A
- anything that brings about the changes needed to return to the system to the set point
13
Q
what is a feedback loop
A
- anything that informs the receptor of the changes to the system brought about by the effector
