5.1 Reflexes

Question 1

what is a reflex?

Answer 1

involuntary response to sensory stimulus

Question 2

state the steps in a reflex arc:

Answer 2

stimulus
receptor
sensory
relay
motor
effector
response

Question 3

what is a withdrawal reflex?

Answer 3

one that involves moving away e.g. hand moving away from a hot object

Question 4

what is the blinking reflex?

Answer 4

the involuntary blinking of the eyelids

Question 5

when does the corneal reflex occur?

Answer 5

when the cornea is stimulated (touched)

Question 6

when does the optical reflex occur?

Answer 6

when the eye is exposed to bright light

Question 7

why is the blinking reflex known as the CRANIAL REFLEX?

Answer 7

occurs in the brain and not the spinal cord

Question 8

1. when the cornea is stimulated the stimulus triggers….

Answer 8

…an impulse along a sensory neurone (fifth cranial nerve)

Question 9

2. the impulse then passes….

Answer 9

….through a relay neurone in the lower brain stem

Question 10

3. impulses are then sent…

Answer 10

…along branches of the motor neurone (seventh cranial nerve)

Question 11

4. this initiates….

Answer 11

…. a motor response that closes the eyelids

Question 12

5. the closing of both the eyelids is called a…

Answer 12

….consensual response

Question 13

when examining unconscious patients why do doctors test for the blinking reflex?

Answer 13

used to determine if the patient is brain dead

reflex is present it indicates lower brain stem is functioning

Question 14

what type of reflex is the knee jerk reflex?

Answer 14

spinal reflex

Question 15

1. the patella is tapped this….

Answer 15

…stretches the patella tendon

Question 16

2. stimulus initiated reflex arc causes the extensor muscle on top of the thigh ….

Answer 16

… to contract

Question 17

3. a relay neurone inhibits the (?) of the flexor muscle causing….

Answer 17

…it to relax

(?) motor neurone

Question 18

4. contraction coordinated with relaxation of antagonistic flexor hamstring muscle….

Answer 18

….causes the leg to kick

Question 19

what could the absence of the knee jerk reflex indicate?

Answer 19

nervous problems

Question 20

what do reflexes prevent or reduce?

Answer 20

the body being harmed / severity of damage

Question 21

reflexes are extremely fast and prevent what?

Answer 21

the brain being overloaded increasing chances of survival