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AA > 2.5 Sensory systems > Flashcards

2.5 Sensory systems Flashcards

1
Q

Sensory homonculus

A

What the male body would look like if each part grew in proportion to the area of the cerebral cortex of the brain concerned with its sensory perception

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2
Q

Frontal lobe

A

Anterior half of cortex, motor functions

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3
Q

Parietal lobe

A

Posterior half of cortex, sensory functions

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4
Q

Stimulus

A

Change in the external or internal environment that causes a reaction-specifically potentials- in peripheral NS receptors

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5
Q

Examples of stimuli

A

Light, sound, touch, chemical odor, chemical taste

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6
Q

Sensation (Perception)

A

Conscious awareness, in the cerebral cortex, of stimuli received by peripheral sensory receptors

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7
Q

1st step of afferent sensory circuit

A

Stimulation and transduction (peripheral sensory receptor neuron transforms stimulus into electrical signals–> graded potentials)

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8
Q

2nd step of afferent sensory circuit

A

Generation of action potentials in the 1st order sensory neuron (may be separate cell from sensory receptor)
-Triggers at threshold stimulus level

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9
Q

AP frequency dictated by…

A

Strength of stimulus and graded potentials

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10
Q

Sensation

A

APs transmission to the thalamus, then to cerebral cortex where selective attention yields conscious perception of a stimulus

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11
Q

What is the thalamus’ role in sensation

A

Filters “noise,” decides whether or not it’s worth it to perceive incoming information

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12
Q

Types of peripheral sensory receptors

A

Exteroreceptors
Interoreceptors
Propioreceptors

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13
Q

Exteroreceptors

A

Monitor external environment; associated with skin (somatic sensory receptors) or special sense organs of the head

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14
Q

Interoreceptors

A

AKA visceral sensory receptors
Monitor internal environment
Associated with internal organs and tissues (ex: blood vessels, visceral organs)

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15
Q

3 types of interoreceptors

A

Chemoreceptors
Thermoreceptors
Stretch receptors

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16
Q

Propioceptors

A

Monitor body position and movements, muscle length / tension, joint positions
Associated with joints, tendons , muscles and vestibular organ

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17
Q

Receptors classified by modes of stimuli

A 
Chemoreceptors
Thermoreceptors
Mechanoreceptors
Photoreceptors
Baroreceptors
Nociceptors
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18
Q

Chemoreceptors

A

Detect chemicals detected in fluid-liquid or airborne

Ex: blood gases, salts, scents in the air, flavors in foods)

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19
Q

Thermoreceptors

A

Respond to changes in temperature

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20
Q

Mechanoreceptors

A

Respond to touch, external pressure, vibration and stretch (mostly skin but also gut and bladder)

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21
Q

Photoreceptors

A

Respond to photons (light)

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22
Q

Baroreceptors

A

Sense pressure by ‘reading’ deformation of a body structure

Ex: blood vessel stretch for blood pressure regulation

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23
Q

Nociceptors

A

React to painful, noxious stimuli, can be both extero and intero (but fewer intero)

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24
Q

Stimulation of a sensory receptor causes…

A

A local dendritic depolarization

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25
Q

Transduction

A

Transforming physical or chemical stimulus into electrical signal

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26
Q

Generator potential

A

The first order neuron itself has has the graded potential and will itself fire the the action potential towards the central nervous system

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27
Q

What do generator potentials apply to?

A

Common, applies to all tactile (mechano) receptors in the skin and visceral organs

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28
Q

Receptor potentials

A

A dedicated receptor experiences a graded potential response that varies with stimulus intensity–> Stimulates action potentials in adjacent first order neuron

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29
Q

What are receptor potentials used by?

A

Relatively rare, used by gustatory and photoreceptors

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30
Q

Tactile (touch) receptors

A

Where generator potentials can start

Often “free nerve endings” (i.e. dendrites) that transduce mechanical stimuli

31
Q

What do deep pressure receptors sense?

A

Vibration

32
Q

What do slowly adapting touch receptors sense?

A

Rough?

33
Q

Skin averages ~ ___ tactile receptors/ square inch

A

400

34
Q

Where are afferent tactile signals processed / perceived?

A

Primary somatic sensory cortex

35
Q

Small receptive fields

A

Surface area of skin occupied by a single receptor

36
Q

Small receptive fields

A

Has many MORE neurons in the primary cortex
(surface area of skin occupied by a single receptor)
-appears larger on “map”
ex: fingers

37
Q

Large receptive fields

A

Represented by fewer neurons in the cortex, appear smaller

ex: trunk

38
Q

Smaller receptive fields allow for what?

A

Very fine spatial resolution of sensations.. impacts two-point discrimination

39
Q

If receptors are numerous and close together, leads to

A

Small receptor fields

40
Q

For generator potentials in a tactile receptor, transduction leads to this type of membrane potential in the dendrite of the first order sensory neuron

A

Graded potential

THERE ARE NOT ACTION POTENTIALS IN DENDRITES

41
Q

What are nociceptors stimulated by?

A

Thermal, mechanical or noxious (potentially damaging) stimuli

42
Q

Chemical stimuli of nociceptors

A

Injuries locally release prostaglandins and other substances that stimulate nociceptors

43
Q

Mechanical stimuli of nociceptors

A

Severe distention (gut, joints), skeletal muscle spasms or a “charlie horse”

44
Q

What do the stimuli of nociceptors initiate?

A

Generator potentials in free nerve endings in skin and visceral organs

45
Q

What happens after there is a generator potential in nociceptors?

A

AP delivered to peripheral NS nerves, ultimately to CNS tracts in DORSAL HORN and GANGLION of the spinal cord

46
Q

The more painful the stimulus…

A

The faster the action potentials fire from nociceptors

47
Q

What do nociceptors express that facilitate Ca2+ release at their presynaptic junctions?

A

μ-opioid receptors

48
Q

Ca2+ release in nociceptors (presynaptic junction) is essential for…

A

Substance P neurotransmitter release

49
Q

What does morphine do in pre-synaptic neuron?

A

It blocks the Ca2+ release in nociceptors in presynaptic junction which stops AP propogation

50
Q

POSTsynaptic sensory neurons in the dorsal horn also express…

A

μ-opioid receptors

51
Q

What do μ-opioid receptors normally do in the post-synaptic sensory neurons?

A

Depolarize the cell..

52
Q

What does morphine do in the post-synaptic neuron?

A

Blocks the μ-opioid receptors and hyper polarizes the post-synaptic dendrite

53
Q

What natural substance can work in a similar fashion to morphine?

A 
Endogenous endorphins
(enkephalins and dynorphins)
54
Q

Propioreceptors provide information about…

A
  • The position and rate of movement of body parts
  • The weight of held objects (golgi tendon organs)
  • The range of movement of a joint
55
Q

Propioreceptors are located in

A
  • Deep skin, joints and muscles (muscle spindles and Golgi tendon organs)
  • Vestibular organ (ears)
56
Q

Where is propioreceptive info typically processed?

A
  • First in the cerebellum (balance, coordination)

- Ultimately perceived as your body sense in the cerebral cortex

57
Q

Propioreceptors are (tonic / phasic)

A

Tonic

Never fatigue

58
Q

Nociceptors are (tonic / phasic)

A

Phasic

Fatigue

59
Q

Trigenimothalamic tract

A

Conveys pain, tickle itch and temperature from face to contralateral cortex (neck up)

60
Q

The Trigenimothalamic is a _____ neuron system

A

3

61
Q

Trigenimothalamic tract: primary

A

Trigeminal (fifth) nerve from face, nose, mouth to brainstem

62
Q

Trigenimothalamic tract: secondary

A

Crosses to opposite side (decussates) in brainstem, enters trigenimothalamic tract, ascends to thalamus

63
Q

Trigenimothalamic tract: tertiary

A

Thalamus to somatosensory cortex

64
Q

Spinothalamic tract

A

Conveys pain, tickle, itch and temperature (from body to contralateral cortex)
Neck down

65
Q

The spinothalamic tract is a ____ neuron system

A

3

66
Q

Spinothalamic tract: primary (1st order)

A

From body periphery to posterior (dorsal) horn of spinal cord

67
Q

Spinothalamic tract: secondary (2nd order)

A

Crosses to opposite side (decussates) in spinal cord, enters spinothalamic tract, ascends to thalamus

68
Q

Spinothalamic tract: tertiary (3rd order)

A

Thalamus to somatosensory cortex

69
Q

Spinocerebellar system

A
  • Carries tonic propioreceptive information to cerebellum (unconscious)
  • Coordinates movement of major motor units (cerebrum) effecting major muscle groups
70
Q

The spinocerebellar is a ____ neuron pathway

A

2

71
Q

Spinocerebellar system: steps

A
  • Primary neuron to spinal cord

- Secondary neuron to ipsilateral cerebellum

72
Q

Does the spinocerebellar system decussate?

A

NO

73
Q

: The vestibular organs in your inner ear contain numerous ___________ that communicate information about body position & balance to the
___________

A

Proprioceptors / cerebellum

74
Q

Where are tactile inputs processed?

A

Primary somatic sensory cortex

AA (21 decks)

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