unit 3a

Question 1

Cutaneous senses

Answer 1

perception of touch & pain f/ stimulation of skin

Question 2

proprioception

Answer 2

ability to sense position of body & limbs

Question 3

Kinesthesis

Answer 3

ability to sense mvmt of body & limbs

Question 4

skin

Answer 4

Largest organ of body , both in surface & weight

Provides many funcs. incl:
- protection (germs, trauma, UV, toxins)
-excretion (water, waste)
-endrocrine processes (vitamin D production)
-regulation of body temp. & water loss
- sensation (tactile info)

*3 layers: Epidermis, Dermis, Subcutaneous Tissue.

Question 5

Epidermis

Answer 5

Outermost, protective layer of skin,
-composed mostly of dead cells

Question 6

Basement membrane

Answer 6

Specialized structure that lies b/t epidermis & dermis

Includes various protein structures linking basal layer of keratinocytes (skin cells) to basement memb. & basement memb. to underlying dermis

Once skin-cancer cells cross this boundary, they can begin to spread thru the body thru vascular syst. of dermis

Question 7

Dermis

Answer 7

Middle layer of skin
- below epidermis
-forms true skin
-contains blood capillaries, nerve endings, sweat glands, hair follicles & other structures

Question 8

Subcutaneous tissue

Answer 8

Deepest layer of skin
- made up of vessels, fat, & connective tissue

Question 9

hairy skin

Answer 9

Most of our skin has hair.
- Primary somatosensory receptor in hairy skin = follicle receptor
→ which is a mechanoreceptor triggered by distortion of hair shaft

Question 10

Glabrous skin

Answer 10

Hairless skin
- contains more specialized types of mechanoreceptors
- ex: on palms, soles, lips

Question 11

Mechanoreceptor

Answer 11

A sensory receptor that responds to mechanical pressure/distortion (stretching, vibration) via mechanotransduction: mvmt of cell membrane, physically pulls open/pushes closed ion channels in the membrane,→ leading to changes in cell signaling

Normally, there are 4 main types in glabrous mammalian skin
-* Pacinian corpuscles
- Meissner’s corpuscles
- Merkel’s discs (AKA Merkel’s receptors)
-Ruffini cylinders (AKA Ruffini endings)
*
These differ along several factors, incl.: morphology, skin location, rate of adaption, frequency selectivity, spatial receptive field, & perceptual task

Question 12

Slowly adapting fibers (SA)

Answer 12

Fire continuously as long as pressure is applied to provide detailed high acuity tactile info
- Found in Merkel’s disks (upper dermis) & Ruffini cylinders (lower dermis)

Question 13

Rapidly adapting fibers (RA)

Answer 13

Fire at onset & offset of stimulation to provide info abt start & stop of a sensation
- found in Messier’s corpuscles (upper dermis) & Pacinian corpuscles (lower dermis)

Question 14

Acute nociceptive pain

Answer 14

-Part of rapid warning relay instructing motor neurons of CNS to minimize detected physical harm. Mediated by nociceptors on A-δ & C fibers

Question 15

nociceptors

Answer 15

-(pain sensors) free nerve endings that terminate just below the skin in tendons, joints & organs. Serve to detect cutaneous pain, somatic pain & visceral pain.

-Specialized for heat, chemicals, severe pressure, + cold. Hot & cold sensations are carried via thermoreceptors

-Threshold of eliciting receptor response must be balances to warn of damage but not affected by normal activity

Question 16

Chronic inflammatory pain

Answer 16

Inflammatory nociceptive pain assoc. w/ tissue damage & resulting inflamm. process
- adaptive in that it elicits physiologic responses that promote healing

Question 17

Chronic neuropathic pain

Answer 17

neuropathic pain produced by damage to neurons in peripheral & Central nervous systems, involves sensitization of these systems
- Peripheral sensitization: increase in stimulation of peripheral nociceptors that amplifies pain signals to CNS
-Central sensitization: neurons (originating in dorsal horn of spinal cord) become hyperstimulated, incr. pain signals to brain & → incr pain sensation

Question 18

Spinal cord

Answer 18

a long, thin, tubular bundle of nervous tissue + support cells (like glia) that extends f/ medulla oblongata (in brainstem) to lumbar region of the vertebral column

the brain + spinal cord =CNS

In contrast to the cortex, grey mater is inside of spinal cord & surrounded by white matter.

Spinal cord has 3 major functions:
- Acts as conduit for motor info → travels down the spina cord, as a conduit for sensory info in the reverse direction & ~ as center for coordinating certain reflexes

Question 19

Vertebral Column

Answer 19

bony structure made of multiple vertebrae that protect the relatively shorter spinal cord.

• Spinal nerves project thru small opening in the vertebral bones

Question 20

Dorsal root ganglion

Answer 20

the sensory nerves of the peripheral nervous system (PNS) have their cell bodies in the dorsal root ganglion

ganglion = group of cell bodies

These cells have projections (like dendrites) that carry info f/ peripheral sensory receptors - peripheral nerve- & also projections (axons) that carry info into spinal cord - dorsal root

Question 21

Ventral root

Answer 21

the motor nerve exiting the spinal cord to innervate muscle fibers

Question 22

Fascicle

Answer 22

a bundle of neuronal axons surrounded by connective tissue
- a component of a nerve

Question 23

Spinal Reflex Pathway

Answer 23

neural pathway that controls a reflex action

As most sensory neurons synapse in spinal cord before going to cortex, spinal motor neurons can rapidly activate w/o waiting for signals to go to/come f/ brains 1st.

Sensory input is sent to brain while the reflex is being carried out

Question 24

Posterior Columns

Answer 24

A set of somatosensory white matter tracts in posterior spinal cord that carry info abt fine touch, vibration, pressure, & joint position f/ the spinal cord to thalamus (→ then to S1)

name turns into ‘medical lemniscus’ when tracts reach the brainstem (where dorsal root ganglion axons then synapse & cross to opposite side. -Organized somatotopically.

Question 25

Spinocerebellar tract

Answer 25

set of somatosensory white matter tracts in the POSTERIOR/ LATERAL spinal cord that carries info abt joint position & muscle fiber tension f/ spinal cord → cerebellum

• projections do NOT cross to opposite side
  -Organized somatotopically

Question 26

Anterior Spinothalamic tract

Answer 26

set of somatosensory white matter tracts in ANTERIOR spinal cord that carries info abt crude touch & pressure f/ spinal cord → thalamus

-dorsal root gang axons synapse & cross immediately to opposite side
- organized somatotopically

Question 27

Lateral Spinothalamic tract

Answer 27

a set of somatosensory white matter tracts in the lateral spinal cord that carries info abt pain & temp f/ spinal cord → thalamus

-dorsal root gang axons synapse & cross immediately to opposite side
- organized somatotopically

Question 28

Thalamus

Answer 28

Sensory ‘relay station’ in brain (located sub cortically) to which all sensory neuronal pathways project prior to entering cortex, EXCEPT those involved in olfaction

Question 29

Primary somatosensory cortex (S1)

Answer 29

a strip of cortex just posterior to central sulcus, where primary ctrl of sensation occurs

-S1 contains a somatotropin (body map) representation
- S2 = 2nd somatosensory area located just inferior & posterior to S1.

Question 30

Somatotopy

Answer 30

the pt-for-pt correspondence of an area of the body to a specific pt on the CNS

• somatotopic organization is present in both S1 & M1

Question 31

Pain matrix

Answer 31

a number of diff. areas of the brain involved in pain perception

Signal f/ nociceptors travel up the spinothalamic pathway & activate many of these areas.
-New research demonstrates that S1 & S2 are also directly involved in pain perception

Question 32

Tactile agnosia

Answer 32

a disorder characterized by inability to identify by touch an object (or characteristics of an object)

-possibly caused by damage to S1
-much like visual agnosia, but symptoms now apply to touch

• Specific tactile agnosia may rise f/ damage to higher-order regions of the somatosensory system, including inability to identify object’s weight/size (but still identify object w/ tactile info)

Question 33

Cotard syndrome

Answer 33

delusional belief that one is dead, DNE, is putrefying or has lost blood or internal organs (‘walking corpse syndrome’)

paradoxical delusions of immortality may also occur (‘I am dead already, so now I can’t be killed’)

Assoc. w/ depression, schizo., capers syndrome, bipolar disorder, migraine, herpes medication.

May arise f/ disconnection b/t high-order sensation/face perception (?) & emotional processing of limbic cortex

Treatments may include electro-convulsive shock therapy (ECT)

Question 34

Congenital analgesia

Answer 34

AKA congenial insensitivity to pain (CIP)

A set of rare conditions in which a person can’t feel (has never felt) physical pain.

Condition may be cause by
1. increased endorphins/natural opioids or
2. mutation in sodium channel in pain receptors

Cause high risk of serious injury, illness, & death

Question 35

Insensitivity to pain

Answer 35

painful stimulus not perceived
- patient can’t describe intensity/type of pain

Question 36

Indifference to pain

Answer 36

patient CAN perceive stimulus but LACKS approp. response
- dont flinch or withdraw when exposed to pain

Question 37

Chronic pain

Answer 37

pain that extends beyond expected period of ealing

-Affects 1/3 of all Americans
-major impacts on quality of life
-creates large economic burden on society

Patients severely underrated, yet it affects more ppl than heart disease, cancer, & diabetes COMBINED

Affective (mood) & emotional effects on pain perception exist but chronic pain is NOT ‘all in patient’s head’

Question 38

Phantom limb syndrome

Answer 38

disorder characterized by having sensations (usually pain) in a limb that is no linger attached to body

Mirror therapy or virtual reality may provide some relief

Although phantom pain can be debilitation, sensation of a phantom limb can improve a person’s ability to use a prosthetic.