unit 9: reflexes

Question 1

how are reflex signalled

Answer 1

receptor
sensory neuron: carries
(action potential) into the cns (brain or spinal cord)

integration center

motor neuron carries efferent signals (action potentials) away from the integration center towards the effector

effector: create response

Question 2

Somatic (skeletal muscle) reflexes

Answer 2

effectors are skeletal muscles that contract in response to signals from the somatic lower motor neurons (knee jerk reflex)

Question 3

Autonomic (Visceral) Reflexes

Answer 3

effectors are smooth muscle, cardiac muscle or glands that contract or secrete in response to signals from sympathetic and/or parasympathetic postganglionic neurons

(sneezing, vomiting)

Question 4

Spinal reflexes

Answer 4

sensory neurons synapse with interneurons or motor neurons in the dorsal, lateral or ventral horn of the
spinal cord. Occur without input from the brain

knee jerk reflex, Micturition (Urination) reflex

Question 5

Cranial reflexes

Answer 5

sensory neurons synapse with interneurons or motor neurons in the brain where integration occurs.

sneezing, Vomiting (effector is smooth muscle of the stomach wall),

Corneal reflex (bilateral blinking of eyes when an object
comes into contact with the cornea – involves skeletal muscle
of the eye – the orbicularis oculi.

Question 6

Monosynaptic reflexes

Answer 6

the reflex arc consists of 2 neurons (a
sensory neuron and a motor neuron) with a single synapse
that connects them (NO interneuron is present).

ex: all stretch reflex

Question 7

polysynaptic reflex

Answer 7

the reflex arc consists of 3 or more
neurons with 2 or more synapses in the pathways (i.e. one or
more interneurons is present in the reflex pathway).

ex All withdrawal reflexes
E.g.2: All crossed extensor reflexes.
E.g.3: Corneal Reflex

Question 8

Ipsilateral reflexes

Answer 8

he sensory and motor neurons are on the same side of the body

E.g.1: All stretch reflexes like the knee jerk (patellar) reflex

E.g.2: All withdrawal (flexor) reflexes - for example putting your
right hand on a hot pan handle and pulling it back right away
even before you feel the pain of the burn

Question 9

Contralateral Reflexes

Answer 9

he sensory and motor neurons are
on opposite sides of the body

ex: All crossed extensor reflexes – interneurons carry the
signal to the opposite side of the spinal cord

Question 10

reflex movements

Answer 10

least complex, integrated in the spinal cord or brainstem

Question 11

reflex movement types (postural, feedforward, stretch)

Answer 11

1. help maintain body position
2. body adjust posture in response to anticipated changes
3. common sense

Question 12

voluntary movements

Answer 12

most complex, integrated in the cerebral cortex

Question 13

rhythmic movements

Answer 13

intermediate complexity, integrated in spinal cord w/ higher center input required to start and stop movement.