08 | Touch, Taste, Movement Flashcards Preview

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Flashcards in 08 | Touch, Taste, Movement Deck (54):
1

__% of taste is smell

75

2

Taste cells do not have ___. They form ___ with afferent nerve in the taste bud.

1. axons
2. chemical synapses

3

Nerves involved in taste

1. VII (facial)
2. IX (glossopharyngeal)
3. X (vagus)

4

How many taste buds on tongue?

5000

5

How many taste receptors per taste bud?

100

6

Which taste modalities use ion channels? G-proteins?

1. salty, sour, bitter
2. sweet, bitter, umami

7

Signalling: salt

Na flow down conc. gradient through Na channels

8

Signalling: sour

1. inward H flow through salt channels
2. Block K channels

9

Bitter compound =

quinine

10

Signalling: bitter (ion)

Block K channel

11

Signalling: sweet, bitter, umami

Gustductin
1. PLC pathway
2. activate cAMP

12

what experiment demonstrated that fat could be a 6th taste modality?

CD36 (FA transporter) found with Gustductin on taste bud

13

What NT is associated with taste receptors?

ATP

14

Which nerve is responsible for signalling spicy?

V -> activate pain pathways

15

Capsaicin receptor is a __ sensitive channel

Ca

16

What are the 2 types of touch receptors?

1. Temperature (but no extremes)
2. Mechanoreceptors

17

What are the 4 capsular structures of touch receptors?

1. Merkel's disk
2. Pacinian corpuscle
3. Ruffini's corpuscle
4. Meissner's corpuscle

18

Where are the most sensitive mechanoreceptors located?

in the ear (hair cells)

19

What NT does Merkel's disk use?

Glutamate

20

What does Merkel's disk sense?

pressure, position, shape

21

What does Pacinian corpuscle sense?

vibrations

22

What does Ruffini's corpuscle sense?

stretch

23

What does Meissner's corpuscle sense?

Initial contract, motion

24

Where can Ruffini's corpuscles be found?

Base of fingernails, tissue around joints and ligaments, palms

25

define: polymodality (and what does it apply to?)

Responds to multiple modalities (free nerve endings)

26

Cell body of touch receptors are located in...

dorsal root ganglion

27

What are the 2 branches of touch receptors?

1. central branch (dorsal root -> spinal cord)
2. peripheral branch (nerve terminal -> brain)

28

Velocity of signal propagation depends on...

1. diameter of nerve
2. myelination

29

Fiber type for light touch. Velocity?

A-β (60 m/s)

30

Fiber type for 1st pain (sting, prickle). Velocity?

A-δ (2-10 m/s)

31

Fiber type for 2nd pain (burn, ache). Velocity?

C (0.2-2 m/s, unmyelinated)

32

Which nerve fibre is responsible for the jerk reflex (e.g. pull hand away from stove)

A-δ

33

What are the 2 ascending touch pathways?

1. dorsal column-medial lemniscal
2. spinothalamic tract

34

Difference between the 2 ascending touch pathways?

- dorsal column makes synapse in the medulla, spino does not
- spino crosses to contralateral side in spinal cord, dorsal column crosses in medulla
- dorsal column senses sensations, spino senses temp and pain

35

Similarities between the 2 ascending touch pathways?

- both make synapse at thalamus
- both end at primary somatosensory cortex
- both have 3 orders or neurons

36

Which sections in the cortex are the primary somatosensory cortex? Where is it located?

1, 2, 3a, 3b

@ anterior parietal lobe

37

What is another name for the primary somatosensory cortex?

postcentral gyrus

38

Which section in the cortex is the secondary somatosensory cortex?

5

39

Touch plasticity

e.g. area devoted to left fingertips in the postcentral gyrus can increase with practice (violin)

40

Each muscle fiber adds __% to tension

5

41

Why are small motoneurons less powerful than larger motoneurons?

Small ones innervate only a few muscle fibers, but large ones innervate more.

42

What is the size principle? Why?

Small motoneurons recruited first, followed by large.

Smaller have larger input resistance, and therefore have bigger changes in voltage (easier to reach threshold with the same input current).

43

Motor cortex is also known as...

precentral gyrus

44

Role of basal ganglia in regulating movement

1. Regulate posture
2. counteract tremor
3. maintain steady muscle contraction

45

Dorsal striatum is made up of...

caudate nucleus + putamen

46

Ventral striatum is made up of

NAc

47

DS release...

GABA, NO

48

Symptoms of Parkinson's

1. Tremor at rest
2. Rigidity
3. Akinesia/bradykinesia

49

Parkinson's ultimately results in what effect on the cortex? What is the pathway?

Decreased

Less DS activity -> less GP inhibition -> more inhibition on thalamus -> less cortical stimulation

50

What causes Parkinson's (in the brain)?

degeneration of SN DA neurons

51

What kind of disease is Huntington's?

autosomal dominant

52

Symptoms of Huntington's

1. cognitive issues
2. lack of coordination
4. spontaneous, disruptive movements
3. dementia

53

At what age does Huntington's show up?

late 20s to early 30s

54

What is the cause of Huntington's (in the brain)?

Degeneration of DS GABA neurons -> less inhibition of extra movements