5.1 Reflexes Flashcards
what is a reflex?
involuntary response to sensory stimulus
state the steps in a reflex arc:
stimulus receptor sensory relay motor effector response
what is a withdrawal reflex?
one that involves moving away e.g. hand moving away from a hot object
what is the blinking reflex?
the involuntary blinking of the eyelids
when does the corneal reflex occur?
when the cornea is stimulated (touched)
when does the optical reflex occur?
when the eye is exposed to bright light
why is the blinking reflex known as the CRANIAL REFLEX?
occurs in the brain and not the spinal cord
- when the cornea is stimulated the stimulus triggers….
…an impulse along a sensory neurone (fifth cranial nerve)
- the impulse then passes….
….through a relay neurone in the lower brain stem
- impulses are then sent…
…along branches of the motor neurone (seventh cranial nerve)
- this initiates….
…. a motor response that closes the eyelids
- the closing of both the eyelids is called a…
….consensual response
when examining unconscious patients why do doctors test for the blinking reflex?
used to determine if the patient is brain dead
reflex is present it indicates lower brain stem is functioning
what type of reflex is the knee jerk reflex?
spinal reflex
- the patella is tapped this….
…stretches the patella tendon
- stimulus initiated reflex arc causes the extensor muscle on top of the thigh ….
… to contract
- a relay neurone inhibits the (?) of the flexor muscle causing….
…it to relax
(?) motor neurone
- contraction coordinated with relaxation of antagonistic flexor hamstring muscle….
….causes the leg to kick
what could the absence of the knee jerk reflex indicate?
nervous problems
what do reflexes prevent or reduce?
the body being harmed / severity of damage
reflexes are extremely fast and prevent what?
the brain being overloaded increasing chances of survival
