Sensory Feedback (week 8) - Part 1

Question 1

state what it is meant by the key term - perception

Answer 1

perception is the process of obtaining information about the internal and/or external environment from sensory stimulation

Question 2

state 3 facts about perception

Answer 2

1. involves motor behaviour (ie - move to perceive, perceive to move)
2. can be modulated by the CNS (ie - how much the sensor responds to a stimulus)
3. often multimodal (integrates multiple senses)

Question 3

state 2 facts about perception’s function

Answer 3

1. relies on specialised nerve cells (receptors) that convert stimuli into a neural signal
2. brings afferent info to the brain (dorsal root) for controlling, planning or deciding

Question 4

state the 5 main structures of a sensory neurone that you need to know

Answer 4

1. cell body
2. axon
3. peripheral fibre
4. central terminal branches
5. dendrites

Question 5

state 2 facts about a sensory neurones cell body

Answer 5

1. contains the nucleus and the cell machinery

2. lies in the dorsal root of the ganglia

Question 6

state 2 facts about a sensory neurones axon

Answer 6

1. carries impulses away form the cell body into the spinal chord
2. can continue up the spinal chord into the brain

Question 7

state 1 fact about a sensory neurones peripheral fibre

Answer 7

carries impulses form the neurones dendrites to the cell body

Question 8

state 1 fact about a sensory neurones central terminal branches

Answer 8

make connections with motor neurone dendrites or interneurones in the spinal chord

Question 9

state 1 fact about a sensory neurones dendrites

Answer 9

carries impulses from the sensory receptors to the peripheral fibre

Question 10

state what it is meant by the key term - sensory receptors

Answer 10

sensory receptors are cells, or organs, that are selective in their response to different types of stimuli - they absorb energy, and convert it into a neural signal

Question 11

sensory receptors can be split into 2 main categories. state the names of these 2 categories

Answer 11

1. exteroceptors

2. interoceptors (viceroceptors and proprioceptors)

Question 12

state 2 facts about exteroceptors

Answer 12

1. located at, or near, the body surface

2. respond to signals coming from the environment - including the 5 senses

Question 13

state 2 facts about interoceptors

Answer 13

1. viceroceptors - respond to stimuli from viscera (Internal organs)
2. proprioceptors - respond to stimuli related to movement or position

Question 14

sensory receptors can also be classified depending on the primary source of the stimulation. state the 5:

Answer 14

1. photoreceptors - sensitive to light
2. mechanoreceptors - sensitive to mechanical inputs
3. chemoreceptors - sensitive to chemical substances
4. thermoreceptors - sensitive to thermal energy
5. nociceptors - sensitive to pain, can fall into multiple categories

Question 15

state 2 introductory facts to sensory adaptation

Answer 15

1. the stronger the stimulus, the higher the firing rate in the afferent axon
2. response tends to decrease over time if the stimulus stays constant

Question 16

explain fast adapting sensory receptors (3 things)

Answer 16

1. stimulus is applied + maintained until stimulus ends
2. receptor sends impulse of high frequency at stimulus recognition and again when the stimulus ends
3. does not continue to send a frequency throughout the whole stimulus (eg - wearing clothes)

Question 17

explain slow adapting sensory receptors (2 things)

Answer 17

1. stimulus is applied + maintained until stimulus ends

2. receptor potential generated at onset of stimulus and maintained until the offset of stimulus

Question 18

state 3 introductory facts about proprioceptors

Answer 18

1. located in the muscles, tendons and joints
2. stimulated by motion
3. their response depends upon the magnitude, direction, and the rate of change in movement

Question 19

state the names of the 2 types of joint and skin proprioceptors

Answer 19

1. paccinian corpuscle

2. Ruffini endings

Question 20

state the name of the labyrinthine and neck proprioceptors

Answer 20

labyrinthine receptor (inner ear)

Question 21

state the names of the 2 muscle proprioceptors

Answer 21

1. muscle spindle

2. golgi tendon organ

Question 22

state what it is meant by the key term - muscle spindles

Answer 22

muscle spindles are proprioceptors which lie between muscle fibres that are sensitive to a change in length

Question 23

state 4 facts about muscle spindles

Answer 23

1. connected by sensory fibres 1 and 2 to CNS
2. innervated by gamma motor neurones to help contraction of muscle spindles
3. when a muscle is stretched, a sensory nerve sends impulses to CNS, which activates motor neurone via a reflex action causing muscles to contract
4. stimulates muscle to produce more force to resist stretching

Question 24

state the names of the two types of intrafusal muscle spindle fibres

Answer 24

1. nuclear bag fibres (all nuclei in middle of fibre)

2. nuclear chain fibres (nuclei lined in a horizontal string)

Question 25

intrafusal muscle spindle fibres both have sensory fibres going back to the CNS. state the names of these sensory fibres

Answer 25

1. annulospiral, fast adapting (type 1)

2. flower-spray, slow adapting (type 2)

Question 26

sensory fibres can be classified into 4 main groups (1, 2, 3 and 4)…

Answer 26

1. type 1 having the largest diameter, 4 the smallest

2. conduction velocity is governed by this diameter

Question 27

annulospiral (AS) receptors are responsible for what?

Answer 27

responsible mainly for phasic response (quick changes in fibre length) and tonic (static) stretch

Question 28

flower-spray (FS) receptors are responsible for what?

Answer 28

register only static stretch in a muscle

Question 29

state what it is meant by the key term - goggle tendon organ (GTO)

Answer 29

GTO’s are sensitive to tension (i.e. force) and are located at the muscle-tendinous junction (i.e. between a muscle and a tendon)

Question 30

state 3 facts about GTO’s

Answer 30

1. type 1b sensory fibre
2. when stretched they cause muscles to relax
3. GTO’s and muscle spindles function together to protect the muscle from excessive stretch and excessive tension

Question 31

state the location of the paccinian corpuscle

Answer 31

paccinian corpuscle is located around joint capsules, ligaments and tendon sheaths

Question 32

state 2 facts about the paccinian corpuscle’s function

Answer 32

1. detect joint angle change, intra-articular pressure and vibration
2. pressure leads to deformation of lamellae and central fibre

Question 33

state the location of Ruffini endings

Answer 33

Ruffini endings are located in the deep layers of the skin or within the joints

Question 34

state 2 facts about Ruffini endings

Answer 34

1. detect joint angle changes and constant intra-articular pressure
2. activated by joint angle change, but also recognise constant pressure - slow/very little adaptation

Question 35

state 2 facts about neck receptors

Answer 35

1. maintenance of equilibrium of the head is due too joint receptors in C1-C3 (cervicle)
2. sensitive to the angle between the body + head

Question 36

state 2 facts about labyrinthine receptors

Answer 36

1. labyrinth recognise orientation + movements in the head

2. 3 semilunar canals at 90 degrees to each other