Ascending And Descending Pathways Flashcards

0
Q

What are thermoreceptors?

A

Temperature response
Cold and hot exist
Some in eye cause vasodilation/constriction
Threshold for pain found here

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1
Q

What is a mechanoreceptor?

A

Receives mechanical stimulus

Responds to stretch [Golgi tendon, muscle spindle fibers]

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2
Q

What are osmoreceptors?

A

Responders that regulate fluid intake and release

Monitor osmotic level of blood

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3
Q

Where are osmoreceptors found?

A

Within the brain and kidney

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4
Q

What are chemoreceptors?

A

Respond to changes in pH (7.42)

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5
Q

Where are chemoreceptors found?

A

Within tissue and hypothalamus

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6
Q

What are nociceptors?

A

Responders for pain

Lets us know something is potentially destroying tissue

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7
Q

Where are afferent receptor cell bodies located?

A

Dorsal root ganglion

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8
Q

What is the largest organ and greatest receptor?

A

The skin

Has mostly mechanoreceptors

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9
Q

What allows skin to be able to desensitize?

A

It has fast and slow adapting receptors

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10
Q

Describe the monosynaptic reflex arc pathway.

A

Sensory receptor -> afferent neuron -> interneuron (to motor neuron, excitatory or inhibitory) -> efferent neuron

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11
Q

What type of epithelium is skin?

A

Keratinized stratified squamous epithelium

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12
Q

What’s the name for hairless skin?

A

Glabrous skin

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13
Q

What are the functions of skin?

A

Protection
Prevention of evaporation
Direct contact with world

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14
Q

What type of somatosensory receptor is most common in skin?

A

Mechanoreceptors

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15
Q

Which mechanoreceptor is rapid-adapting, encapsulated, and responsible for light touch?

A

Meissner’s corpuscles

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16
Q

Which mechanoreceptor is responsible for light touch and tickling and is slow-adapting?

A

Merkel’s discs

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17
Q

Which mechanoreceptor is responsible for deep pressure, is encapsulated, and is slow-adapting?

A

Ruffini endings

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18
Q

Which mechanoreceptor is onion-like, responsible for detecting vibration and deepest pressure, and is fast-adapting?

A

Pacinian corpuscles

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19
Q

Which mechanoreceptor is also found in the pancreas?

A

Pacinian corpuscles

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20
Q

What size are Pacinian corpuscles?

A

1-4mm

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21
Q

The order of 2-point discrimination:

A

:index finger -> thumb -> lip -> big toe -> forearm -> sole -> back -> calf

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22
Q

How does a rapid-adapting response graph look?

A

Initial response peak when you first stimulate, then another peak when you stop

23
Q

Which mechanoreceptors are fast-adapting?

A

Pacinian corpuscles and Meissner’s corpuscles

24
Q

Which mechanoreceptors are slow-adapting?

A

Merkel’s discs and Ruffini endings

25
Q

How does a slow-adapting response graph look?

A

Fires the most at initial response and continues firing during the duration, firing rate decreases until stimulus is removed

26
Q

Which mechanoreceptors are mostly in the hand?

A

Meissner’s corpuscles and Pacinian corpuscles

27
Q

What is lateral inhibition?

A

Stimulating nerves lateral to nerve that was initially stimulated

28
Q

Aa afferent axon characteristics:

A

Most myelination, fastest
13-20um
80-120 m/s
Proprioceptors of skeletal muscle

29
Q

AB afferent axon characteristics:

A

6-12 um
35-75 m/s
Mechanoreceptors of skin (touch)

30
Q

A£ afferent axon characteristics:

A

1-5 um
5-30 m/s
Pain and temperature receptors

31
Q

C afferent axon characteristics:

A

No myelination, slowest
0.2-1.5 um
0.5-2 m/s
Temperature, pain, and itch receptor

32
Q

How does the dorsal column medial lemniscus pathway travel up the spinal cord?

A

Ipsilateral

33
Q

How does the anterolateral pathway travel up the spinal cord?

A

Contralateral

34
Q

Why are the lateral dorsal columns of the spinal cord larger?

A

It has to carry sacral and lumbar information

35
Q

What are dermatomes?

A

Spinal nerve distribution areas

Disease follows these

36
Q

Shingles characteristics

A

Follows dermatomes
Is unilateral
About an inch wide
Most dangerous one is along ophthalmic division of CN5

37
Q

Characteristics of fast pain:

A

Stimulation from mechanical and thermal receptors
A£ fibers carry signal
Prickling sensation
Easily localized

38
Q

Characteristics of slow pain:

A

Stimulation of polymodal nociceptors
C fibers carry signal
Poorly localized

39
Q

The dorsal horn contains:

A

: Cell bodies of interneurons, where afferent neurons terminate

40
Q

The lateral horn contains:

A

: cell bodies of autonomic efferent nerve fibers

41
Q

The ventral horn contains:

A

: cell bodies of somatic efferent neurons

42
Q

How does acupuncture work?

A

It stimulates endogenous morphine to inhibit pain

Opiate neurons inhibit pain neurons from going to the thalamus

43
Q

What is the main descending pathway?

A

Corticospinal pathway

44
Q

Corticospinal pathway

A

Large fiber bundles -> decussation at brainstem -> terminate on LMN in ventral horn of SC

45
Q

Rubrospinal secondary pathway

A

Red nucleus -> Ipsilateral in SC -> ventral horn

46
Q

Which pathway can be regenerated with physical therapy after injury?

A

Rubrospinal pathway

47
Q

Which feedback loop causes ALS?

A

Spinal cord -> muscle contraction and movement -> sensory receptors -> spinal cord

48
Q

What happens from the frontal cortex to the premotor cortex?

A

Analysis and getting ready

49
Q

What happens at the local level of voluntary movements?

A

The movement

Specific muscles that move

50
Q

What percent of force muscle degeneration between 30-80 years of age?

A

30-40%

51
Q

How does Polio affect the body?

A

It destroys motor neurons

52
Q

How does ALS affect the body?

A

Affects motor neurons

Excitotoxic: over excitation of glutamate to motor neurons, extra Ca2+ in excels

53
Q

What type of disorder is muscular dystrophy?

A

X-linked

54
Q

What are costamers?

A

A structural binding protein that links mayo fibrils to sarcolemma

55
Q

What protein is responsible for the effects of muscular dystrophy?

A

Dystrophin

56
Q

Why does muscular dystrophy occur?

A

Dystrophin protein built incorrectly -> as myofibril does it’s job it rips the sarcolemma and muscle atrophies