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Midterm

PSYC 211 Study Guide - Midterm Guide: Bulbous Corpuscle, Transient Receptor Potential Cation Channel, Member A1, Subcutaneous Tissue


Department
Psychology
Course Code
PSYC 211
Professor
Yogita Chudasama
Study Guide
Midterm

Page:
of 2
Echolocation&works&like&a&sonar;&the&bat&navigates&by&the&echoes&that&it&hears&&
A&bat&with&a&40cm&wingspan&can&navigate&through&opening&in&a&14&x&14&cm&mesh&made&from&very&
fine&nylon&thread&while&flying&in&total&darkness&&
&
Somatosenses:&provide&information&about&what&is&happening&on&the&surface&of&the&skin&and&inside&it&&
There&are&three&interacting&somatosensory&systems:&&
The&exteroceptive&system&senses&external&stimuli&applied&to&the&skin&(e.g.&touch)&&
The&proprioceptive&system&monitors&information&about&the&position&of&the&body&and&its&posture&
(e.g.&kinesthesia)&&
The&interoceptive&system&provides&information&about&conditions&within&the&body&(e.g.&blood&
pressure)&&
Organic&sense:&A&sense&modality&that&arises&from&receptors&located&within&the&inner&organs&of&the&body&&
&
The&stimulus&
The&cutaneous&senses&(skin&senses)&respond&to&different&types&of&stimuli:&&
Vibrations&occur&when&we&move&our&fingers&across&a&rough&surface&&
Pressure&is&cause&by&mechanical&deformation&of&the&skin&&
Temperature&is&produced&by&objects&that&heat&or&cool&the&skin,&free'nerve'endings&&
o It&is&relative&not&absolute,&although&there&is&a&point&of&neutrality&which&depends&on&prior&
history&of&thermal&stimulation&of&that&area.&&
o Increases&in&temperature&lower&the&sensitivity&of&warmth&receptors&and&raise&the&
sensitivity&of&cold&receptors.&&
o Decreases&in&temperature&increase&the&sensitivity&of&warmth&receptors&and&decrease&the&
sensitivity&of&cold&receptors&&
o Two&categories&of&thermal&receptors:&&
Those&that&respond&to&coolness,&located&just&beneath&the&epidermis,&conveyed&
to&the&CNS&by&thinly&myelinated&Aδ&
Those&that&respond&to&warmth,&located&more&deeply&in&the&skin,&conveyed&to&
CNS&by&unmyelinated&C&fibers&&
Pain&is&caused&by&events&that&cause&tissue&damage&&
o Three&types&of&pain&receptors:&&
High&threshold&mechanoreceptors&are&free'nerve'endings&that&respond&to&
intense&pressure,&which&might&be&caused&by&something&striking,&stretching&or&
pinching&the&skin.&&
Second&type&of&free&nerve&ending&(TRPV1)&responds&to&extremes&of&heat,&to&
acids&and&to&the&presence&of&capsaicin&(chile&peppers)&&
TRPA1&receptors&provide&information&about&the&presence&of&chemicals&that&
produce&inflammation&&
Itch:&all&we&know&is&that&there&are&two&different&types&of&neurons&&
Pain&and&itch&are&mutually&inhibitory&
&
Anatomy&of&the&Skin:&&
Ruffini&Corpuscles:&sensitive&to&light&touch,&skin&stretch&and&kinesthetic&sense&of&finger&position&
and&movement&&
Merkel’s&disks:&respond&to&skin&indentations&
Glabrous&skin:&hairless&skin&(e.g.&fingertips,&foot&soles,&etc.)&&
The&dermis&and&epidermis&make&up&two&layers&of&subcutaneous&tissue.&Receptors&are&scattered&
throughout&these&layers&&
Meissner’s&corpuscles:&respond&to&low&frequency&vibrations&(e.g.&taps&on&the&skin)&&
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Pacinian&Corpuscles:&respond&to&skin&vibrations.&They&consist&of&a&concentric&layer&wrapped&
around&dendrite&of&a&single&axon&&
&
Mechanoreceptor:&a&sensory&neuron&that&responds&to&mechanical&stimuli&
When&dendrites&of&mechanoreceptors&bend,&ion&channels&open,&producing&receptor&potential.&&
&
From&the&Skin&to&the&Primary&Somatosensory&Cortex:&The&Somatosensory&Pathway&&
Axons&from&the&skin,&muscles&and&internal&organs&enter&the&CNS&via&the&spinal&nerves&(e.g.&dorsal&root&
ganglia)&&
1. Localized&information&(e.g.&fine&touch)&ascends&through&the&dorsal&column&of&the&white&matter&of&
the&spinal&cord&and&enter&the&medial&lemniscus&via&the&medulla&&
2. The&axons&ascend&to&the&ventral&posterior&nucleus&of&the&thalamus&and&project&to&the&primary&
somatosensory&cortex&&
3. Nonlocalized&information&(pain&or&temperature)&enter&the&spinal&cord,&cross&to&the&other&side&
and&ascend&through&the&spinothalamic&tract&&
4. Organic&Sensibility&reaches&the&CNS&by&means&of&axons&that&travel&through&nerves&of&the&
autonomic&nervous&systems.&&
The&somatosensory&cortex&has&a&columnar&arrangement&where&neurons&respond&to&particular&type&of&
stimulus&applied&to&a&particular&part&of&the&body.&&
The&primary&and&secondary&somatosensory&cortical&areas&are&divided&into&at&least&five&different&
maps&of&the&body&surface,&cells&respond&to&a&particular&submodality&of&somatosensory&receptors&&
o Slowly&adapting&cutaneous&receptors&
o Rapidly&adapting&cutaneous&receptors&&
o Receptors&that&detect&changes&in&muscles&length&&
o Receptors&located&in&the&joints&
o Pacinian&corpuscles&&
&
The&Somatosensory&Homunculus:&&
Penfield&applied&electrical&stimulation&to&various&sites&on&the&somatosensory&cortical&surface&&
Patients&reported&somatosensory&sensations&in&various&parts&of&their&bodies&&
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