Sensory Receptor and Pathways

Definitions

  • Receptors: Transducers that convert external or internal stimuli into electrical signals

  • Sensory Pathways: Neural pathways that carry information from the receptors to the central nervous system integrating centres

  • Sensation: Basic mechanisms by which we detect stimuli from internal and external environments

  • Perception: Interpretation of information by CNS, triggers response

    • Conscious

    • Subconscious

Sensory Receptors

Receptors ↓

Cell membrane or cytoplasmic receptor proteins

Specialized cells or structures for the transduction of various stimuli into electrical signals

↓

Central Receptors / Peripheral Receptors


Sensory Receptors can be classified by the stimulus to which they are most sensitive

Type of Receptor

Modality

Receptor

Location

Mechanoreceptor

(Pressure, displacement)

Touch

Hearing

Vestibular

Pacinian Corpuscle

Hair cell

Hair cell

Skin

Ear

Ear

Photoreceptor

Vision

Rods and cones

Retina

Chemoreceptors

Smell

Taste

Arterial PO2

pH of CSF

Olfactory receptor

Taste buds


Nose

Tounge

Carotid and aortic body

Medulla

Thermoreceptors

Temperature receptors

Cold/warm receptors

Skin

Nociceptors

Extremes of pain/temp

Thermal nociceptors

Polymodal nociceptors

skin

Skin

Sensory Receptor can be classified by their structure

  • Simple neural receptor → Free nerve endings

  • Complex neural receptor → Specific histological structures

  • Special senses receptor → Specific receptor cells

How does the brain interpret the sensory signal?

  • Location

    • Receptive field

      • Area w/in the receptor responds to a stimulus

      • Each sensory pathway projects to a region of the cerebral cortex dedicated to a specific receptive field

  • Modality/type of stimulus

    • The CNS recongnises the receptor type activated and therefore the nature of the stimulus

  • Intensity of stimulus

    • Determined from the number of activated receptors and frequency of action pot in afferent pathway