Somatosensory system & Special Senses Flashcards
Cell bodies location
Cell bodies are located in two regions:
- adjacent to the spinal cord dorsal root ganglia, DRG
- base of skull -trigeminal, TG (CNV)
Wilder Penfield
Cortical Homunculus
Mechanorepectors Channel type
Involves Transient Receptor Potential (TRP) channels
Proprioceptors axon types
A alpha fibers (myelianted)
Hapsis axon type
A beta fibers (myelianted)
itch/tickle axon type
C fibers (unmyelianted)
thermoreceptors axon type
C fibers (unmyelinated) & A delta fibers (myelinated)
nociceptors axon type
Fast- A delta (myelinated)
Slow - C fibers (unmyelinated)
Referred Pain (Dermatomes)
Heart localized to the neck, left shoulder & arm
Stomach localized above umbilicus
Colon localized below umbilicus
ex: shingles -> tiny bumps form on skin when nerves are damaged
Cranial Headache (Meningitis)
inflammation of meninges
Cranial Headache (migraine)
vasospasm then vasodilation
Cranial Headache (hangover)
irritation of meninges by alcohol biproducts
Extracranial Headache (Tension)
emotional tension of muscles of neck/scalp
Extracranial Headache (Sinus Headache)
irritation of nasal structures
Extracranial Headache (eye strain)
excessive contraction of ciliary muscles (for focusing) or of facial muscles
Somesthesia
“Somesthesia is the perception of bodily sensations that include the skin, muscles, joints, and tendons. Such sensations would encompass the perception of pain, temperature, light touch, deep touch, vibration, proprioception (recognition of the relative position of a body part), and kinesthesia (awareness of movement of a limb or joint
Sensory systems, unlike somatosensory systems do not involve
- dorsal root ganglions or trigeminal ganglions instead they are located in the cranial sensory ganglia
- somatosensory conveys information in series but sensory conveys in a nerve bundle
Dysgeusia
reduced sense of taste
causes: : Diabetes Mellitus, hypothyroidism, some meds, throat or tongue infections, chronic smoking, viral load
ageusia
complete loss of taste
Hyposmia
reduced sense of smell
Underlying causes: head trauma, Parkinson’s, Alzheimer’s, some meds, chronic smoking, viral load
Anosmia
temporary loss of smell
Deuteranomaly
(green shifted towards red)
Deuteranopia
(absence of green cones)
Protanomaly
(red shifted towards green)
Protananopia
(absence of red cones)
tritanomaly
reduced sensitivity to blue light
tritanopia
absence of blue cones
illusion
- An illusion occurs when physical stimulus and visual perception do not correspond
- Complex perceptual phenomena
- Link between sensory stimulus and cognitive processing poorly understood
- How the brain perceives the same visual image in different ways is also not known
Synesthesia
Stimulation of one sensory pathway results in automatic stimulation of different sensory pathway
Auditory Cortex and Association Areas
- Arranged by tonotopic maps
- High frequency sounds at one end of map; low frequency sounds at other end of the map
- Discrimination of sound patterns is lost when auditory cortex destroyed
cataracts
- Impairments in Vision
- Clouding of lens
glaucoma
Damage to optic nerve
Impairments in Vision
age-related macula degeneration
Damage to retina
Impairments in Vision
scotoma or blind spot
lesion of retina
Impairments in Vision
Diabetic retinopathy
damage to retinal vessels
impairment in vision
Myopia/Hyperopia
Changing shape of eye (decreased visual acuity)
impairment in vision
Nerve deafness
impairment of the cochlea or the auditory nerve
Conduction deafness
impairment of tympanic membrane or ossicles
-Congenital deafness
occurs from birth whereas adventitious deafness occurs after birth (usually noise related)
