Class Notes (811,485)
Canada (494,756)
Physiology (634)
PSL300H1 (220)
Lecture 8

Lecture 8 - Somatosensory Receptors

6 Pages
Unlock Document

Michelle French

PSL300H1F Lecture 8, Sept 28 range so need the CP to discriminate fine textiles Somatosensory receptors Type: mechanoreceptor Cutaneous receptors: detect skin pressure and stress Proprioceptors: detect forces in muscles and joints Cutaneous receptors Sensory axons classified by conduction velocity A-: large diameter; only mechanoreceptive (50 m/s) A: small diameter, myelinated; mechano-, thermo-, and nociceptors (10 m/s) C: small diameter, unmyelinated (1 m/s) N axon terminal in centre w lamellae around it Ic inner core modified schwann cells, commuicate w axon by synapses, release gaba (common inhibitory) onto the terminals so opens cl channels so depolarizing and cancels depolarizing receptor pot so rapidly-adapting since depolarization doesnt stick around Most in dermis (deep layer) Pacinian corpuscle in sub-dermis All axons associated w other cells that capsulate the terminals (developed from glial cells, have to shape the response pattern whether slowly or rapidly adapting in a specific afferent) Merkel is the tiniest of the exiliary cells, associated w terminals of merkel afferents Pacinian corpuscle A alpha largest cutaneous receptor so biggest axon and fastest conduction velocity Continuous chain of act pots in PC huge receptive field ex. In palm so huge Minute vibrations from rubbing ridges in fingers located deep in dermal layers; hands, feet Need PCs to discriminate fine textures and rapidly-adapting so responds to changes; discriminate btwn vibrations responds best to skin vibration at 200-250 Hz Might get spike when release pressure Partially due to inhibitory gaba transmitter from very sensitive (threshold about 0.5 micro m) inner core lamellae are modified Schwann cells surrounding lamellae in PC with GABAergic synapses on axon corpuscle actively shapes the response needed for fine texture discrimination; fingerprints amplify skin vibrations (~250 Hz) as finger rubbed on object surface, ridges on fingertips finger print - vibrations in the freqwhere sweat glands attached), maybe because its right underneath the ridge so most transmission of process through the ridge and not the valley respond as long as pressure applied to skin receptive field spread across a number of ridges due to afferent branching and terminating under a number of ridges red circles = receptive fields of indiv afferents in the smooth skin dots = sweat pores the smaller the finger higher density of merkels, small receptive fields Pacinian in subdermis deep layer, any stimulant in the receptive field of the afferent can activate ie. Females have smaller fingers so smaller it w vibration receptor fields higher discrimination ability to Meisser- higher up in dermis, rapid acting, not tactile detail than the larger receptor field as sensitive, pressure pulses w spikes at onsets, 1-2mm across, gets larger when away from fingertips (ex. 1-2cm on your back) Merkel Cell Hair Follicle Receptors slowly adapting; in fingers, cluster around sweat In hairy skin, there are no Pacinian corpuscles, gland ducts but there are other rapidly adapting receptors: all others found in hairy skin replaced by rapidly Merkel cell or dis
More Less

Related notes for PSL300H1

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.