Sensory Receptors and Afferents 2

Sensory Receptors and
Afferents 2
Classification of nerve fibers
Large myelinated A-beta fibers

transmit mechanical stimuli



Small myelinated A-delta fibers

cold receptors



Small unmyelinated C fibers

transmit pain and temperature




velocity of tansmission is directly proportional to the


Impulses travel by saltatory conduction in the myelinated
fibers. this is achieved via the nodes of ranvier


neighbourhood depolarization -


Classification of nerve fibers

Erlanger-Gasser Classification

Lloyd Roman Numeral System




The organization of sensory pathways



Sensory Receptors and Afferents 2 1

, First order neurons

sensory neurons that
deliver sensory
information to the CNS



Second order neurons

First order neurons
synapse on these in the
brain or spinal cord




Third order neurons

Found in the thalamus

Second order neurons synapse on these




🧠 only 1% of incoming sensory impulses actually reach the
cerebellum




sensation felt on the right goes to the left side of the brain

sensations felt on the left goes to the right side of the
brain

ie. to the contralateral cerebrum




Sensory Receptors and Afferents 2 2