coordination Flashcards
1
Q
why do multicellular organisms evolve specialised systems?
A
to respond to internal & external stimuli
2
Q
what is meant by ‘stimuli’?
A
changes in the environment that elicit a response
3
Q
give 2 examples of stimuli
A
- changes to external environment eg temperature, sounds or predator appearance
- changes inside organism eg temperature, pH or water potential
4
Q
what is external stimuli?
A
a change in an environment factor outside of the organism’s body
5
Q
what is internal stimuli?
A
a change in an environment factor inside the organism’s body
6
Q
give 4 examples of external stimuli
A
- sudden sound
- air humidity
- light intensity
- sea temperature
7
Q
give 4 examples of internal stimuli
A
- blood temperature
- blood glucose conc
- blood pH
- water potential of cell cytoplasm
8
Q
why do cells in different parts of the body need to communicate?
A
- enzyme controlled reactions can only take place if suitable conditions
- cells need to monitor & respond to changes from these conditions
- allows a dynamic equilibrium to be maintained close to optimum
9
Q
name 3 ways in which cells communicate with each other
A
- cell signalling
- nerves
- hormones
10
Q
describe how nerve cells communicate with each other
A
- change in stimuli is detected
- nerve impulses pass along sensory neurones to the brain
- nerve impulses pass along motor neurones to effectors which respond
- individual neurones communicate with adjacent neurones using neurotransmitters across synapses
11
Q
describe how hormones allow cells to communicate with each other
A
- chemical messengers are released from cells in one part of the body
- they travel to target cells
- cell surface receptors have a complementary shape to that hormone
- allows specific hormones to affect specific cells
12
Q
why is communication so important?
A
- animals can respond to environment
- increases chance of survival
- keep internal environment at optimum for metabolic reactions
