08 | Touch, Taste, Movement

Question 1

__% of taste is smell

Answer 1

75

Question 2

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

Answer 2

1. axons

2. chemical synapses

Question 3

Nerves involved in taste

Answer 3

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

Question 4

How many taste buds on tongue?

Answer 4

5000

Question 5

How many taste receptors per taste bud?

Answer 5

100

Question 6

Which taste modalities use ion channels? G-proteins?

Answer 6

1. salty, sour, bitter

2. sweet, bitter, umami

Question 7

Signalling: salt

Answer 7

Na flow down conc. gradient through Na channels

Question 8

Signalling: sour

Answer 8

1. inward H flow through salt channels

2. Block K channels

Question 9

Bitter compound =

Answer 9

quinine

Question 10

Signalling: bitter (ion)

Answer 10

Block K channel

Question 11

Signalling: sweet, bitter, umami

Answer 11

Gustductin

1. PLC pathway
2. activate cAMP

Question 12

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

Answer 12

CD36 (FA transporter) found with Gustductin on taste bud

Question 13

What NT is associated with taste receptors?

Answer 13

ATP

Question 14

Which nerve is responsible for signalling spicy?

Answer 14

V -> activate pain pathways

Question 15

Capsaicin receptor is a __ sensitive channel

Answer 15

Ca

Question 16

What are the 2 types of touch receptors?

Answer 16

1. Temperature (but no extremes)

2. Mechanoreceptors

Question 17

What are the 4 capsular structures of touch receptors?

Answer 17

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

Question 18

Where are the most sensitive mechanoreceptors located?

Answer 18

in the ear (hair cells)

Question 19

What NT does Merkel’s disk use?

Answer 19

Glutamate

Question 20

What does Merkel’s disk sense?

Answer 20

pressure, position, shape

Question 21

What does Pacinian corpuscle sense?

Answer 21

vibrations

Question 22

What does Ruffini’s corpuscle sense?

Answer 22

stretch

Question 23

What does Meissner’s corpuscle sense?

Answer 23

Initial contract, motion

Question 24

Where can Ruffini’s corpuscles be found?

Answer 24

Base of fingernails, tissue around joints and ligaments, palms

Question 25

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

Answer 25

Responds to multiple modalities (free nerve endings)

Question 26

Cell body of touch receptors are located in...

Answer 26

dorsal root ganglion

Question 27

What are the 2 branches of touch receptors?

Answer 27

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

Question 28

Velocity of signal propagation depends on...

Answer 28

1. diameter of nerve | 2. myelination

Question 29

Fiber type for light touch. Velocity?

Answer 29

A-β (60 m/s)

Question 30

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

Answer 30

A-δ (2-10 m/s)

Question 31

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

Answer 31

C (0.2-2 m/s, unmyelinated)

Question 32

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

Answer 32

A-δ

Question 33

What are the 2 ascending touch pathways?

Answer 33

1. dorsal column-medial lemniscal | 2. spinothalamic tract

Question 34

Difference between the 2 ascending touch pathways?

Answer 34

- 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

Question 35

Similarities between the 2 ascending touch pathways?

Answer 35

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

Question 36

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

Answer 36

1, 2, 3a, 3b @ anterior parietal lobe

Question 37

What is another name for the primary somatosensory cortex?

Answer 37

postcentral gyrus

Question 38

Which section in the cortex is the secondary somatosensory cortex?

Answer 38

5

Question 39

Touch plasticity

Answer 39

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

Question 40

Each muscle fiber adds __% to tension

Answer 40

5

Question 41

Why are small motoneurons less powerful than larger motoneurons?

Answer 41

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

Question 42

What is the size principle? Why?

Answer 42

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).

Question 43

Motor cortex is also known as...

Answer 43

precentral gyrus

Question 44

Role of basal ganglia in regulating movement

Answer 44

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

Question 45

Dorsal striatum is made up of...

Answer 45

caudate nucleus + putamen

Question 46

Ventral striatum is made up of

Answer 46

NAc

Question 47

DS release...

Answer 47

GABA, NO

Question 48

Symptoms of Parkinson's

Answer 48

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

Question 49

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

Answer 49

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

Question 50

What causes Parkinson's (in the brain)?

Answer 50

degeneration of SN DA neurons

Question 51

What kind of disease is Huntington's?

Answer 51

autosomal dominant

Question 52

Symptoms of Huntington's

Answer 52

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

Question 53

At what age does Huntington's show up?

Answer 53

late 20s to early 30s

Question 54

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

Answer 54

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