13.8 Reflexes Flashcards
what is a reflex action?
response to a stimulus without conscious decisions
what is the reflex arc?
stimulus
receptor
sensory neurone
relay neurone
motor neurone
effector
response
why is a reflex quicker?
less synapses to pass through (synapses are slowest part of transmission)
what is the structure of the spinal chord?
what is the knee-jerk reflex action?
when patellar is tapped, starts a reflex arc which leads to extensor muscle to contract and the leg to kick
describe the knee-jerk reflex
- patellar hit
- patellar tendon stretched
- stimulus created and carried by sensory neurone
- stimulus relayed at relay neurone
- stimulus carried by motor neurone to flexor muscle
- extensor muscle contracts
- flexor muscle relaxes
- kick response
what is the knee-jerk reflex for?
used by the body to maintain balance and posture
what is the blinking reflex?
involuntary blinking of the eyelids when the cornea is stimulated
what is the blinking reflex for?
keeps the cornea safe from damage
why is the blinking reflex a cranial reflex?
occurs in the brain not the spinal cord
describe the blinking reflex?
- cornea is stimulated by contact
- impulse triggered along sensory neurone
- impulse passed through relay neurone in brain
- impulse carried in motor neurone
- impulse reaches effector and closes the eyelids
why are reflexes useful?
involuntary response
- prevents the brain from being overloaded
no learning needed
- allows for protection from birth
very fast
- provides quick response
