Neurophys 8

Question 1

Components of reflex

Answer 1

Sensory receptor
Sensory neuron
Synapse in CNS
Motor neuron
Effector organ

Question 2

Types of reflex

Answer 2

Monosynaptic - sensory neuron directly synapses w motor neurons
Polysynaptic - one or more Interneurons between sensory and motor neurons

Question 3

Types of reflexes

Answer 3

Segmental
Intersegmental
Suprasegmental

Question 4

Segmental arc length

Answer 4

One or a few spinal cord segments

Question 5

Intersegmental arc lengths

Answer 5

Multiple spinal cord segments

Question 6

Suprasegmental arc length

Answer 6

Arc involves synapses in the brain

Question 7

Myotatic reflex

Answer 7

“Stretch reflex”
Muscle stretches to induce muscle contraction & relaxation of contra lateral muscle

Question 8

Muscle spindle

Answer 8

Sensory organ
Short intramural muscle fibers

Question 9

Muscle spindle Innervation - sensory

Answer 9

Type 1a - info abt muscle length & velocity of cont
Type 2 - info about muscle length

Question 10

Muscle spindle Innervation - motor

Answer 10

Gamma motor neurons

Question 11

Muscle spindle contraction

Answer 11

Extrafusal fibers contract - intrafusal fibers contract
Innervated by gamma motor neurons

Question 12

Golgi tendon organs location & arrangment

Answer 12

Located in tendons
Innervated by type 1b sensory fibers
Arranged in series w extrafusal muscle fibers

Question 13

Golgi tendon organs - info

Answer 13

Provide info on degree of muscle contraction
Prevents damage from excessive muscle contraction

Question 14

Golgi tendon organ - Interneurons

Answer 14

Sensory info carried by group 1b afferent
- inhibits agonist alpha motor neurons (relax)
- excite antagonist alpha motor neurons (contract)
“Inverse myotatic reflex”

Question 15

Withdrawal reflex function

Answer 15

Polysynaptic
Sensory receptor = nociceptor (pain)

Question 16

withdrawal reflex action

Answer 16

Flexion of ipsilateral limb
Extension of contra lateral limb (stabilize the body)

Question 17

Cutaneous trunci reflex - muscle

Answer 17

Sheet of subQ muscle located in thorax
Functions to twitch off insects
Innervated by lateral thoracic nerve (C8-T1)
Contains no muscle spindles

Question 18

Cutaneous trunci reflex

Answer 18

Stimulation of lateral skin causes skin twitch
Used to localize spinal cord lesions

Question 19

Myotatic reflex specifics

Answer 19

Sensory organ = muscle spindle
Monosynaptic
Segmental
Occurs in all skeletal muscle (quads, patellar reflex)

Question 20

Arrangment of muscle spindle

Answer 20

Surrounded by fibrous capsule
Arranged in parallel to extrafusal fibers
Maintains postures

Question 21

Lesions & reflexes - upper MN

Answer 21

brain, cranial spinal cord
- normal to increased reflexes (hyperreflexia)
- normal to increased muscle tone (spastic paralysis)

Question 22

Lesions & reflexes - lower motor neuron

Answer 22

Spinal cord, grey matter, nerve
- decreased reflexes (hyporeflexia)
- decreased muscle tone (flaccid paralysis)

Question 23

Diving reflex involvement

Answer 23

Polysynaptic
Sense organ - touch and thermoreceptors
Afferent nerve - trigeminal (V)
Synapses - brainstem nuclei, including vagus

Question 24

diving reflex output

Answer 24

Parasympathetic (vagus) to heart
Inhibits respiration and causes bronchoconstriction