Section 3a: Sensory Contribution Flashcards

1
Q

Why do we need sensory information?

A

Sensory Feedback is important so we learn how to navigate and interact with our world using our motor behaviour

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2
Q

where do the sensory feedback receptors stem from?

A

head
muscles
joints
skin

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3
Q

what are the parts of the neuron

A
  • cell body: where the nucleus is
  • dendrites: branches of cell body and connects to other neuron’s
  • axon: where the electric signal travels by propagating down
  • presynaptic terminal: where there neurotransmitters are made & stored in vesicles
  • postsynaptic neuron- the neuron that receives the signal from the other neuron’s by the neurotransmitters
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4
Q

what are the 4 functional components that generate signals

A

-receptive components: dendrite
- Integrative Component: for Sensory its the first node of ranvier; for motor/interneurons its the axon hillock
- signalling components: axon to conduct action potential
- Secretory: a post synaptic terminal

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5
Q

what are the 3 types of neurons

A

Sensory- (afferent) PNS to CNS
Motor (Efferent) CNS to PNS
Interneurons: in CNS connecting the sensory info to motor neurone

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6
Q

what’s the resting membrane potentials?

A

-65 to -70mV

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7
Q

what are the states of a neuron

A

depolarization: when the inside of the membrane has become more positive by the increase Na+ in the membrane
hyperpolarization: when the inside of the membrane have become more negative than resting potential due to efflux of K+ ions

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8
Q

what are the 3 types of potentials?

A
  • Receptor Potential
  • Synaptic Potential
  • Action Potential
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9
Q

Describe an Action potenial

A

it occurs when a receptor or synaptic potential is able to change the resting membrane potential to its critical threshold of -55mV. Then a positive feedback loop of depolarization by Na+ channels occurs and increases until +50mV

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10
Q

describe a receptor potential

A

sensory receptors relieve energy and causes a disturbance in the resting membrane potential but as signal travels passively, it loses amplitude

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11
Q

describe a synaptic potential

A

similar to receptor except a neurotransmitter release from one neuron causes a disturbance in the post synaptic neuron altering the resting membrane potential but is also decreases in amplitude as it travels

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12
Q

What are the 2 features of the signal from neuron?

A
  • number of action potentials
  • time between the action potentials
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13
Q

what 4 features are the nervous system extracting from the signals they receive

A
  • modality: type of stimulus
  • intensity: the frequency and number of receptors as firing (population coding), area sensitivity
  • duration: how long stimulus is detected
  • location: some area of skin have large receptive fields and others have small to detect fine stimuli
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14
Q

how does the brain know about modality or location?

A

labelled line concept- each neuron is delivering one aspect of information from a place in the body and the nervous system knows what information is carried by what neurons

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15
Q

what is proprioception?

A

the sensation and perception of limb, trunk and head position

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16
Q

what are the 3 types intrafusal muscle fibres

A

nuclear bag
- dynamic 1 bag
- static 2 bag
chain fibres

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17
Q

what does dynamic 1 bag detect?

A

changes in muscle length and limb/muscle movement

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18
Q

what does static bag 2 detect?

A

static length or position of muscle

19
Q

what does the chain fibre detect?

A

static length or position of muscle

20
Q

which sensory neurons are connected to which intrafusal muscle fibre

A

Group 1a - Dynamic Bag 1, Static Bag 2 and Chain
Group 2 - Static Bag 2 and Chain

21
Q

what does motor neurons are connected to which intrafusla muscle fibre?

A

gamma dynamic - dynamic bag 1
gamma static - static bag 2 and chain

22
Q

what is the motor gamma dynamic neuron job?

A

increase sensitivity to muscle length changes

23
Q

what is the motor gamma static neuron job?

A

increase sensitivity to muscle length position

24
Q

what neurons detect changes in length

A

motor - gamma dynamic
afferent - group 1a

25
Q

what neurons detect stationary length and position of muscle

A

motor- gamma static
afferent- group 2 (MOSTLY), group 1a (minor)

26
Q

which muscles have the highest muscle spindle density

A

(extraocular) eye muscles, hand and neck

27
Q

what are extrafusal muscle fibres?

A

regular muscle fibres

28
Q

what is alpha gamma co activation and why is it important

A

its the motor neurons working together. if they alpha neurons where to move on their own the gammas wouldn’t know and the muscle would be stuck in that state. But since the muscles move tother, the motor neurons can detect changes and signal the alpha when to change again

29
Q

monosynaptic

A

when it goes directly from afferent to motor

30
Q

disynaptic

A

when afferent goes to interneuron then motor

31
Q

what are GTOs and what do they do

A

Golgi Tendon organs- they are receptors and the muscle tendon junction that detect load or force
- only care about shortening

32
Q

what is special about GTOs

A

they aren’t connected to the CNS

33
Q

what sensory neuron is connected to the GTOs

A

group 1b

34
Q

techniques that study proprioception

A
  • deafferentation
  • sensory neuropathy
  • muscle/tendon vibration
35
Q

what is deafferentation

A

surgical- removing afferent pathways
temporary deafferentation - circulation cut off

36
Q

sensory neuropathy

A

diabetes stops their afferent nerves from working
- they can’t sense their limbs
- can’t copy movement without seeing their own limb

37
Q

muscle/tendon vibration

A

distorts the group 1a afferents
- may think muscle is lengthening

38
Q

touch is based on what type of receptors

A
  • pacinian corpuscle
  • meissner corpuscle
  • Ruffini’s corpuscle
  • merkel’s disk
  • free nerve endings
39
Q

pacinian corpuscle detection

A

vibration

40
Q

meissner corpuscle

A

stroking and vibration

41
Q

merkel’s disk

A

pressure

42
Q

ruffini’s corpuscle

A

skin stretch

43
Q

free nerve endings

A

pain

44
Q

how does sensory info reach the brain

A

through dorsal root ganglion to the primary somatosensory