Lecture 9: Reflexes

Question 1

____ extends from brain stem

Answer 1

Spinal cord

Question 2

Spinal cord has 2 functions :
- serves as the neuronal link between the ___ and the _____
- is the integrating centre for the spinal ____

Answer 2

Brain and peripheral nervous system
Reflexes

Question 3

___ pairs of spinal nerves emerge from spinal cord through spaces between adjacent vertebrae

Answer 3

31

Question 4

Spinal nerves connect with each side of the spinal cord by a ___ and a ____

Answer 4

Dorsal root
Ventral root

Question 5

a spinal nerve consists of both ___ and ___ fibres

Answer 5

Efferent
Afferent

Question 6

A ___ is a bundle of peripheral neuronal axons enclosed by a connective tissue covering and following the same pathway

Answer 6

Nerve

Question 7

White matter is organized into ___

Answer 7

Nerve tracts

Question 8

_________: Bundles of nerve fibres with a similar function. Each tract begins or ends within a particular area of brain

Answer 8

Nerve tracts

Question 9

____ tracts: afferent, sensory input

Answer 9

Ascending

Question 10

____- tracts : efferent motor output

Answer 10

Descending

Question 11

What are the 3 horns that gray matter is divided into ?

Answer 11

Dorsal
Ventral
Lateral

Question 12

_____ horn contain cell bodies of interneurons on which afferent neurons terminate
_____ horn contains cell bodies of efferent motor neurons supplying skeletal muscles
_____ horn contains cell bodies of autonomic nerve fibres

Answer 12

Dorsal

Ventral
Lateral

Question 13

A ____ is an involuntary stereotyped response to a sensory input

Answer 13

Reflex

Question 14

2 types of reflexes ?

Answer 14

Simple /basic
Acquired / conditional

Question 15

2 types of reflexes :
______ : built in , unlearned response
______ : result of practice and learning

Answer 15

Simple/basic
Acquired/ conditioned

Question 16

___________
-> somatic motor neurons and skeletal muscles
- > spinal - integrated in spine
-> cranial - integrated in brain

__________
-> involve autonomic neurons
-> spinal- urination/defecation
-> integrated in brain - brainstem , hypothalamus , thalamus (homeostasis -gag, vomiting, sneezing, coughing, swallowing)

Answer 16

Somatic
Autonomic

Question 17

What are the 5 reflex pathway components?

Answer 17

Sensory receptor
Afferent pathway
Integrating centre
Efferent pathway
Effector

Question 18

1. A ______ (muscle spindles in the case of somatic muscle reflexes)
   2.an _______ to the CNS (sensory axon)
2. An _____ consisting of one or more synapses in the CNS
3. An ____- to the periphery ( motor axon)
4. An ___ (the muscle)

Answer 18

Sensory receptor
Afferent pathway
Integrating centre
Efferent pathway
Effector

Question 19

A _____ has a single synapses between the afferent and efferent neurons

Answer 19

Monosynaptic reflex

Question 20

______ have two or more synapses

Answer 20

Polysynaptic reflexes

Question 21

What are 3 Proprioceptors :

Answer 21

Muscle spindle
Golgi tendon organ
Joint receptors

Question 22

Skeletal muscle reflex sensory receptors ( proprioceptors)
_______- in muscles, sense stretch
________- in tendon , sense force
________- sense pressure , position

Answer 22

Muscle spindles
Golgi tendon organ
Joint receptors

Question 23

Muscle stretch triggers a _____

Answer 23

Stretch reflex

Question 24

_____- alpha motor neurons are stimulated to generate contraction

Answer 24

Isotonic contraction

Question 25

Muscle contraction and receptor responses -Length changes, but the ____ remains constant

Answer 25

Tension

Question 26

When the whole muscle mass shortens the _____ also passively shorts

Answer 26

Spindles

Question 27

The firing rates of the spindle afferent axons are reduced because the tension in the receptor portion of the ________ is relieved

Answer 27

Interafusal fibres

Question 28

_______ modulate the sensitivities of the spindles

Answer 28

Y motor neurons

Question 29

The _______ slacken when a muscle shortens (unloading spindles)

Answer 29

Intrafusal fibres

Question 30

To ensure that info on changes in muscle length are transmitted , the CNS regulates the loading of the intrafusial fires with _______

Answer 30

Y motor neurons

Question 31

The rapid contraction of the intrafusial fibres increases the ____ on the central sensory element of the spindle and restores the sensitivity of the spindle During voluntary movement, a and y motor neurons are coactivated by the ____

Answer 31

Tension CNS

Question 32

______: The addition of a load stretches the muscle and the spindles , creating a reflex contraction

Answer 32

Muscle spindle reflex

Question 33

_______ respond to changes in muscle tension

Answer 33

Golgi tendon organs

Question 34

Encapsulated receptors consisting of______ from the muscle intertwined with the endings of tendon afferent axons

Answer 34

collagen fibres

Question 35

Applying tension to collagen fibres, squeezes the axons, ____ them and triggering ___ in tendon afferents

Answer 35

Depolarizing Action potentials

Question 36

Afferents terminate on ________ in ventral Horn and clarke’s nucleus

Answer 36

Inhibitory interneurons

Question 37

Primary function of Golgi tendon organs is to provide _______

Answer 37

Sensory information on muscle tension

Question 38

_____ reflex - monosynaptic reflex - ex: patellar tendon reflex - preliminary assessment of nervous system function

Answer 38

Stretch

Question 39

Classic example of the stretch reflex ?

Answer 39

Patellar tendon reflex

Question 40

____ reflex: stretch reflex and reciprocal inhibition

Answer 40

Patellar

Question 41

____ reflex is an example of a polysynaptic reflex

Answer 41

Flexion

Question 42

____ injury-> damage to any part of PNS reduces or laminates the muscle stretch reflex and reduces muscle tone

Answer 42

LMN

Question 43

_______: Reduction/elimination of muscle stretch reflex

Answer 43

Hyporeflexia

Question 44

LMN injury causes loss of _____ to muscle

Answer 44

Innervation to muscle

Question 45

_____ injury-> increased tone , hyperreflexia

Answer 45

UMN

Question 46

____- lower motor neuron, effector neuron in spinal cord _____- upper motor neuron, neurons in higher brain levels that influence neurons in spinal cord

Answer 46

LMN UMN

Question 47

______ are important because they provide an objective sign medicating an abnormality and some indication to the level of the abnormality

Answer 47

Reflexes

Question 48

The responsiveness of reflexes can be altered by ____ or ____

Answer 48

Trauma or disease

Question 49

__________ - interruption of reflex arc by either peripheral sensory or lower motor neuron (LMN) lesions

Answer 49

Loss/reduction of reflex

Question 50

__________ - injury to upper motor neuron (UMN) above the anterior horn cell leads to loss of descending inhibition

Answer 50

Increased reflex and muscle tone