LECTURE 28 - closed loop control - - proprioception

Question 1

what are the four proprioceptor types ?

Answer 1

1. vestibular
2. muscle receptors
3. joint receptors
4. cutaneous receptors

Question 2

what is a proprioceptor ?

Answer 2

a sensory receptor which receives stimuli from within the body, especially one that responds to position and movement

Question 3

sensory information comes from propeioceptor types and provides _____

Answer 3

information

Question 4

what is the vestibular system ?

Answer 4

is a sensory system that is responsible for detecting and processing information about balance and spatial orientation

Question 5

where is the vestibular system located ?

Answer 5

in the inner ear

Question 6

how many structures does the vestibular system consist of ?

Answer 6

consists of two structures called the utricle and the saccule, as well as three semicircular canals

Question 7

what does bending of the cilia do ?

Answer 7

sends the output to know the movements

Question 8

what are semicircular canals ?

Answer 8

• three fluid-filled “half-circles”
• provide information regarding position of the head compared to the rest of the body
• sensitive t each directional plane

Question 9

describe the horizontal (lateral) canal :

Answer 9

detects head rotation around vertical axis (i.e., spinning)

Question 10

describe the anterior canal :

Answer 10

detects head rotation in the sagittal plane (i.e., nodding up and down)

Question 11

describe the posterior canal :

Answer 11

detects head rotation in frontal planes (i.e., completing a somersault)

Question 12

angular acceleration are detected by _____

Answer 12

semicircular canals

Question 13

what does sensory mismatch lead to ?

Answer 13

motion sickness (simply can close eyes to try to help)

Question 14

what type of organs detect changes in gravity and accelerations ?

Answer 14

otolith organs

Question 15

what are the two otolith organs ?

Answer 15

utricle and saccule

Question 16

what changes does the utricle detect ?

Answer 16

change in horizontal movement and linear acceleration (e.g., walking) - important for eye movements

Question 17

what changes does the saccule detect ?

Answer 17

changes in vertical movement and linear acceleration (i.e., elevator sensation) - important for posture

Question 18

what is the utricle important for ?

Answer 18

eye movements

Question 19

what is the saccule important for ?

Answer 19

posture

Question 20

what does VOR stand for ?

Answer 20

vestibular ocular reflex

Question 21

what is the vestibular ocular reflex ?

Answer 21

• a reflexive movement of the eyes that helps to stabilize vision during head movement
• it is a critical component of the vestibular system and works by generating eye movements in response to movements of the head

Question 22

what are the 3 steps of VOR :

Answer 22

1. detection of rotation
2. inhibition/excitation of extra ocular muscles on one side/on the other side
3. compensating eye movement

Question 23

what is the term used to “lock the ocular muscles on the target object” ?

Answer 23

fixation

Question 24

what happens if someone looses VOR ?

Answer 24

they cannot focus / maintain their target image

Question 25

If your head is moving back and forth but your eyes are looking straight, it means that your vestibulo-ocular reflex (VOR) is ________

Answer 25

working properly

Question 26

what is the primary goal of the VOR ?

Answer 26

to stabilize vision during head movement by generating equal and opposite movements of the eyes in response to movements of the head

Question 27

what is nystagmus ?

Answer 27

an involuntary eye movement characterized by repetitive oscillations of the eyes. It can be either horizontal, vertical or rotary in nature, and can be present in one or both eyes. Nystagmus can occur in a rhythmic or non-rhythmic pattern and can be slow or fast.

Question 28

describe eyes when nystagmus is present :

Answer 28

- non intact - more watery - rapid one way and smooth the other - involuntary

Question 29

describe muscles spindles (intrafusal) :

Answer 29

- cigar-shaped structures connected in parallel with extradural muscle fibers - innervated by gamma-motorneurons - provide information about stretch of the muscle - many types; type 1a and type II - provide system with information about limb position

Question 30

describe type 1a muscle spindles :

Answer 30

sensitive to rapid stretch of the muscle (i.e., when the agonist first begins contraction) (velocity dependent)

Question 31

describe type II muscle spindles :

Answer 31

sensitive to sustained against contract

Question 32

what is info from muscle spindles very important for ?

Answer 32

environment awareness

Question 33

what type of stretch is 1a muscle spindles sensitive to?

Answer 33

dynamic

Question 34

what type of stretch is II muscle spindles sensitive to ?

Answer 34

static

Question 35

what is the monosynaptic stretch reflex ?

Answer 35

- is a reflexive response of the muscle to stretch - it is a simple reflex arc that involves only one synapse between sensory neurons and motor neurons.

Question 36

what are the four steps of the monosynaptic stretch reflex ?

Answer 36

1. hammer strike on patella tendon results in stretch of the quad muscles 2. muscle spindles of quads send stretch info to the spinal cord (CNS) 3. single synapse onto alpha motoneuron of quads and contraction of that muscle 4. the simplest of all stretch reflexes - only one synapse

Question 37

what type pop muscle spindles have been stretch during a monosynaptic stretch reflex ?

Answer 37

type 1a

Question 38

what is hyperreflexia ?

Answer 38

a lot of reflexes

Question 39

what are two postural control strategies ?

Answer 39

hip and ankle strategy

Question 40

describe the ankle strategy :

Answer 40

- standing on a moving platform - small adjustments of the ankle joint to maintain a stable base of support - effective in maintaining balance in the sagittal plane - is activated when the body experiences small perturbations, such as a gentle push or a shift in weight - distal to proximal

Question 41

describe the proximal to distal :

Answer 41

- standing on a moving platform - much slower and less efficient - more likely to lead to a fall - requires recruitment of many muscles - proximal to distal

Question 42

which postural control strategy is more likely to lead to fall, injury, etc.

Answer 42

hip strategy

Question 43

what does GTO stand for ?

Answer 43

golgi tendon organ

Question 44

describe the golgi tendon organ :

Answer 44

- located in metro-tendinous junction between muscle and tendon - provide information about tension (force) in the muscle - prevents ov erstratch and rupture by inhibiting alpha-motorneuron - oligosynaptic

Question 45

what does oligosynaptic mean ?

Answer 45

multiple neurones associated with this pathway