E1 Stimulus and Response Flashcards
Define stimulus
A change in the environment (external or internal) that is detected by a receptor and elicits a response
Define response
A change in an organism (an action) resulting from a stimulus
Define reflex
A response that is rapid and involuntary (unconscious)
Describe the role of receptors in the response of animals to stimuli
Detect stimuli and transform them into electrical nerve impulses
Describe the role of sensory neurons in the response of animals to stimuli
Relay the nerve impulse to the central nervous system (via the dorsal root of the spinal cord)
Describe the role of relay neurons in the response of animals to stimuli
Transmit nerve impulses within the CNS
Describe the role of motor neurons in the response of animals to stimuli
Receive nerve impulses from the CNS (via the ventral root) and relays the signal to an effector
Describe the role of effectors in the response of animals to stimuli
Produce a response to the stimulus (can be muscles or glands)
Describe the role of synapses in the response of animals to stimuli
The junctions between two nerve cells and transmission of a signal across these junctions require chemical neurotransmitters
Explain how hedgehog behaviour has been affected by natural selection
- Hedgehogs exhibit different self-defensive responses to danger across different populations: curing into a ball to expose spines which create a shield for skin body and limbs, or running away
- In areas where there are vehicles and roads, hedgehogs that run away when faced with danger (oncoming vehicles) will be favoured over ones which curl into a ball, as the spines will not protect against oncoming vehicles
- Thus hedgehogs which run away are selected for by the environment