Intro + Sensory Receptors

The Peripheral nervous system PNS consist of

all neural structures outside of the brain and spinal cord

• Sensory receptors

• Peripheral nerves (axons and dendrites) and ganglia (cell bodies)

• Motor nerves

Division of PNS

PNS

• Sensory afferent division

• Motor efferent division

  • Somatic nervous system

  • Autonomic nervous system (ANS)

    • Sympathetic

    • Parasympathetic

Sensory receptors

detect and respond to stimuli (changes in environment)

When sensory receptors are activated

they create a graded potential → if strong enough action potential

What are the 5 stimulus type classifications of sensory receptors

Mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, nociceptors

Mechanoreceptors

responds to touch, pressure, vibration, itch

Thermoreceptors

detect temperature changes

Photoreceptor

Detects light (ex: retinas)

Chemoreceptors

detects chemicals like smell taste and changes in blood chemistry

Nociceptors

Detects pain (extreme cold and heat, excessive pressure, inflammatory chemicals)

What are the three classification of sensory receptors by location

exteroceptor, interoceptor, proprioceptor

Exteroceptors

respond to external environments (ex: touch smell vision, etc)

Interoceptors (visceralceptors)

Respond to internal stimulis from organs (ex: blood pressure or organs stretching)

Proprioceptors

detect and respond to body’s position and movement (ex: knowing where your arm is without looking or touching your nose)

your muscles joints tendons

What are the 2 structural complexity classification of sensory receptors

General and special senses

General senses

Simple receptors like touch pain and temp

Special senses

complex organs

vision, hearing, smell, taste

Sensation and where does it happen

awareness of stimulus ( change in internal and external environment )

input comes from sensory receptors and the it gets sent to the brain where we become aware of the stimulus

Perception and where does it happen

conscious interpretation of stimulus

in the brain

What are the three levels of sensory integration

Receptor level, circuit level, perceptual level

Receptor level of sensory integration

sensory receptor detects the stimulus

Circuit level of sensory integration

signal travels up ascending pathway of spinal cord and brainstem

integration

Perceptual level of sensory integration

Cerebral cortex interprets → final understanding

Adaptation of sensory receptor

receptors become less sensitive over time if the stimulus is constant

Phasic receptors

fast adapting → fire a lot at first but stops/slows down if stimulus is constant

detects change

ex: pressure, touch, smell (clothing)

Tonic receptors

Slow adapting receptors or doesnt adapt at all → keeps firing if stimulus continues

ex: nociceptors (pain) and most proprioceptors