Block 2 Exam: Somatosensory Information Flashcards
Describe Mechanoreception in organs.
- artery distension.
- stretch in digestive organs
- bladder
Pacinian Corpusles
Rapidly Adapting (large receptive fields) Deep in skin
Functions: VIBRATION through mechanically gated ion channels. Also signals dynamic CHANGES
Meissner’s Corpusles
Rapidly Adapting
Superficial (shallow) layers of skin
Functions: Stroking, fine movements, grip control, where 2 point discrimination is best developed
Ruffini Endings
Slowly Adapting (enlarged nerve endings) Deep in skin
Signal presence of Stretch or tension.
Merkel’s Disks
Slowly adapting (enlarged nerve endings) Shallow in skin
Steady pressure on skin. Also texture and edges. Fire AP which stimulus present to keep TRP channels going. Directly related to pressure intensity
A-alpha fibers
PROPRIOCEPTORS of skeletal muscle: where your body is in space.
Intrafusial fibers
A-beta fibers
General Touch/MECHANORECEPTORS
Hair follicle, Meissner Corpusle, Merkel
Adelta/C fibers
Free nerve endings
Though pain heat and itch are slower, reflex mechanisms will let you withdraw.
Outer layer of skin=
Inner layer of skin=
Epidermis
Dermis
A-delta are ____ nociceptors, whereas C are ____ nociceptors.
Mechanical
Polymodal
Spinal Lesions in Cervical areas could cause dermatomes…
Neck, upper back, arms and hands
Spinal Lesions in Thoracic areas could cause dermatomes…
Middle back, breast/chest and stomach, small part of arm
Spinal Lesions in Lumbar areas could cause dermatomes…
Lower back, front legs down to toes
Spinal Lesions on Sacral areas could cause dermatomes…
Genitalia/buttocks, back of legs down to outer foot.
Homunculus
The idea that in the somatosensory cortex, places with more fine sensory info (ex: hands) take up more room.
2-point Discrimination
Why discriminate points closure on fingers than lower back. Within back, few receptors in large receptive fields.
3 Factors
- Higher density of mechanoreceptors
- Small receptive fields
- More cortical tissue devoted to finer areas.
That fact that surrounding areas invade cortical areas that lose innervation is known as
Cortical Map Plasticity
Proprioception is on the _____ side and has info go through Dorsal _____.
Ipsilateral
Dorsal Columns
Nociception (pain) is on the _____ side and has info go through Dorsal ____.
Contralateral
Dorsal Horn
Proprioception:
Upper (thoracic/cervical)–>
Lower (sacral/Lumbar)–>
Upper (thoracic/cervical)–> Lateral (cuneate Fasiscle)
Lower (sacral/Lumbar)–> Medial (gracile fascicle)
Pain:
Upper (thoracic/cervical)–>
Lower (sacral/Lumbar)–>
Upper (thoracic/cervical)–> Medial (gracile Fascicle)
Lower (sacral/Lumbar)–> Lateral (cuneate Fascicle)
Review of Dorsal Column Medial Lemniscal Pathway:
Primary neurons –> Secondary neurons in dorsal column nuclei –> Crosses at medial leminsus –> VPL of thalamus –> Somatosensory cortex (postcentral gyrus/posterior paracenteral gyrus)
Name the four types of nociception
Pain=
- Mechanical-strong pressure (crude touch)
- Thermal- extreme temperature
- Chemical- histamines/chemicals
- Polymodal
Pain=tissue damage
After injury, pain receptors exhibit increased sensitivity after injury. They have a lower threshold and are more responsive (AP). What is this called?
Hyperalgesia
