Somatosensory systems

Question 1

Merkle cells are located within the -____ and are specialized for

Answer 1

epidermis; touch

Question 2

Encapsulated receptors include Meisner’s corpuscles in the dermal papilla specialized for -_____. Ruffini endings are mostly for detection of _____ and Pacinian corpuscle are very rapidly adapting and are mostly for ____

Answer 2

Touch; Ruffini for stretch; Pacinian for vibration.

Question 3

Specialized free nerve endings wrap around hairs and detect ____; however, the sensation is not ____

Answer 3

light touch; not well-localized

Question 4

A-alpha nerve fibers:

Answer 4

muscle fibers. largest in size

Question 5

A-beta nerve fibers:

Answer 5

second largest in size. Touch, pressure, and joint proprioception

Question 6

A-gamma nerve fibers:

Answer 6

motor to muscle fibers

Question 7

A-delta nerve fibers:

Answer 7

mechanoreceptors and nociceptors

Question 8

B nerve fibers

Answer 8

preganglionic sympathetics

Question 9

C nerve fibers

Answer 9

postganglionic ANS, thermoreceptors, and nociceptors

Question 10

First order neurons in the ______ have cell bodies in the ____ and ____ and connect to second order neurons in the _____ which convey the signal to the _____. Finally, third order neurons connect the thalamus to the ____ _____

Answer 10

Peripheral nervous system; cell bodies in the DRG and cranial nerve sensory ganglion
second order neurons in the CNS convey signals to the Thalamus.
3rd order connect to Cerebral cortex

Question 11

dorsal column-medial lemniscus system

Answer 11

well localized, fine tactile information, as well as vibratory sense and conscious proprioceptive information from the body

Question 12

anterolateral system/spinothalamic tract

Answer 12

pain, temperature and poorly localized, crude touch sensation. emotional responses to pain like anxiety/suffering

Question 13

trigeminal mechanosensory system

Answer 13

fine tactile and conscious proprioception from the face

Question 14

spinal trigeminal system

Answer 14

mediates pain, temperature and crude tactile information in the face and anterior head

Question 15

dorsal spinocerebellar and cuneocerebellar tracts

Answer 15

unconscious information to the cerebellum

Question 16

The receptors for the anterolateral system are:

Answer 16

nociceptors, thermoreceptors and mechanoreceptors. Type III & 4, lightly myelinated/umyelinated

Question 17

Nociceptors detect ____ stimuli which is conveyed through two types of neurons: ____ for “fast” and ___ for “slow”

Answer 17

intense stimulation; Adelta receptors&raquo_space; sharp, “fast” pain and C receptors for throbbing or burning “slow” pain

Question 18

The TRPV1 receptor is a channel in nociceptors that responds to:

Answer 18

heat, acid, and capsaican

Question 19

nociceptor sensitization is caused by:

they release the neurotransmitter ____ which causes:

Answer 19

inflammatory mediators like bradykinins and prostaglandins that lower the threshold for activation.
nociceptors release Substance P, which causes vasodilation and activates mast cells to release histamine, which further activates nociceptors.

Question 20

nociceptor sensitization leads to ____ and ____

Answer 20

allodynia: non-painful stimuli feel painful
hyperalgesia: painful stimuli feel even more painful

Question 21

What is the dorsolateral tract of Lasseur?

Answer 21

tract of first order neurons located at the edge of the dorsal horn and is comprised of axons of the small dorsal root ganglia neurons

Question 22

In the dorsal horn, first order neurons synapse with second order dendrites in which zones?

Answer 22

marginal zone and lamina V, as well as substantia gelatinosa –> lamina V

Question 23

second order neurons decussate in the:

Answer 23

anterior white commissure

Question 24

second order axons from the spinothalamic tract synapse w/ third order cell bodies primarily in the:

Answer 24

VPL (ventral posterior lateral) nucleus of the thalamus

Question 25

Cell bodies in the VPL convey information through third order neurons to the ___ _____ cortex in the ____ gyrus

Answer 25

primary somatosensory cortex in the post central gyrus.

Question 26

Pain is represented proportional to sensitivity, which is known as:

Answer 26

the sensory homunculus.

Question 27

what is the periaqueductal gray matter of the midbrain:

Answer 27

activates descending pain-modulating system using neurotransmitters like serotonin and norepinephrine

Question 28

pain-suppression systems are activated by:

Answer 28

endogenous opiates

Question 29

what is the gate control theory of pain:

Answer 29

large, mechanoreceptors can override pain by activating pain inhibitors