Section 6 - Reflexes Flashcards
What is a stimulus (1)
- Any change in the internal or external enviornment
How does responding to their enviornment help organisms survive (4)
- Animals increase their chances of survival by responding to changes in their external enviornment
- Also respond to changes in their internal enviornment, to make sure the conditions are right for their metabolism
- Plants also increase their chances of survival by responding to changes in their enviornment
- Any change in the internal/external enviornment is called a stimulus
Where are receptors found and what is their job (2)
- Sense organs (eyes ears etc)
- Detect external stimuli
What are effectors and give two examples of what they do (3)
- Cells that bring about a response to stimuli
- Muscle cells contract
- Glands secrete hormones
What are the 3 types of neurone (3)
- Sensory
- Motor
- Relay
What does the Central nervous system consist of (2)
- Brain
- Spinal cord
When receptors detect a stimulus, what do they do? (1)
- Send electrical impulses along sensory neurones to the CNS
What is the CNS’s role in a response (3)
- CNS sends electrical impulses to an effector
- Along a motor neurone
- Effector then responds accordingly
Coordinated responses always need a …….. , a ……….. and an ……….. (3)
- Stimulus
- Receptor
- Effector
When someone shines a bight light in your eyes, what happens and why (3)
- Pupils automatically get smaller
- So less light gets into the eye
- Stops it getting damaged
What is the main job of the CNS (1)
- Coordinate the response
What are reflexes (1)
- Automatic responses to certain stimuli
After a cupcake candle burns your finger, what happens (1)
- Stimulaton of the pain receptor
After your pain receptors are stimulated, what happens (1)
- Impulses travel along sensory neurones
After impulses travel along the sensory neurone, what happens (2)
- Impulses are passed along a relay neurone
- Via a synapse
What travels along sensory neurones (1)
Impulses
After impulses are passed along a relay neurone, via a synapse, what happens (2)
- Impulses travel along a motor neurone
- Via a synapse
After impulses travel along a motor neurone via a synapse, what happens (1)
- When impulses reach muscle, it contracts
What order do impulses travel along receptors (3)
- Sensory
- Relay
- Motor
When a stimulus is detected by receptors, an impulse is sent along a ……. neurone to the ……
- Sensory
- CNS
What is the fibre called which carries impulses to the effector (1)
- Axon
What is the axon covered in (1)
- Mylelin sheath
What are the five steps in the reflex arc (5)
What are two purposes of the myelin sheath (2)
- Prevents short circuits with other axons
- Speeds up conduction of impulses
