Sensory Receptors and Afferents 1

Sensory Receptors and
Afferents 1
Objectives

sensory receptors

classification of receptors

mechanism of generation of AP in sense organ

explain why receptors respond to specific stimuli and how
the organization of a receptor affects its sensitivity

identify major sensory pathways

explain how we distinguish among sensations that originate
in different areas of the body

functions of laminae

dermatomes



Sensory receptors

these are structures which have the ability to convert one
energy form into an electrical form. i.e. action potential




🧠 action potential moves while electrical potential does
not move




Functions:

transduction - conversion of stimulus energy into membrane
potential

amplification - receives the stimulus and amplifies it so
that the CNS can detect it



Sensory Receptors and Afferents 1 1

, transmission - conducting impulses to CNS

integration - processing the information via the summation
of graded potentials



Different sensory modalities perceived by the human brain

special senses: vision, smell, hearing, rotational and
linear acceleration and taste

general senses: touch, pressure, cold, warmth, pain, joint
position and movement

senses that does not reach to consciousness: muscle length
and tension, arterial blood pressure, inflation of lungs



Classification of receptors
By location

exteroceptors

interoceptors

proprioceptors (muscle spindles, golgi tendon organs, joint
capsules)



By modality

mechanoreceptors

thermoreceptors

chemoreceptors

photoreceptors

nociceptors



By structure

unencapsulated: free nerve endings, merkel discs, hair
follicle receptors




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