Reflexes and Sensory Processing

sensory processing

1. sensation initiated at skin and and activates sensory neuron

2. impulse from activation enters spinal cord in AFFERENT neuron

3. Takes info from PNS and conveys to CNS

sensory receptors

nerve endings that transduce energy from one form to another (info conveyed to CNS for processing

motor control: activation

the EFFERENT process of muscle contraction

• voluntary (i.e cortical in nature)

• involuntary (i.e reflexive in nature)

reflexes

• below level of cerebrum

• hard-wired responses

below level of cerebrum

• spinal cord: spinal reflex arc

• brainstem: complex reflexive and motor patterns

hard wired responses

automated, involuntary responses to stimuli

• i.e knee jerk

• present in early postnasal period

activation vs. inhibition

muscles operate in opposition of other muscles

• agonists and antagonist (fine, graded movements)

• graded inhibition

• rigidity or spastic paralysis

agonist

contraction of muscle

antagonists

relaxes or graded inhibition

graded inhibition

modulated movements

rigidity or spastic paralysis

co-contraction of muscles in opposition

spinal reflex arc

most basic of reflexive systems in body

• receptor organ

• sensory neuron that conveys info

• interneuron

• motor neuron

muscle spindle

LENGTHEN AND PASSIVE

• sensory receptor in muscle fiber sensing muscle length

  • controls muscle tone

  • prevents injury of overstretching

  • found in all muscles

• purpose: provide sensory feedback to muscle that have been passively stretched

golgi tendon organs (GTO

TENSION AND ACTIVE

• sensors within the tendons that sense tension during muscle contraction

• two attachments

• purpose: responds to active muscle contraction

muscle spindle and golgi tendon organs

they work together (don’t stretch too far or contract too much)

• info passes by dorsal root fibers

  • afferent fibers

categories of sensory receptors

• somatosensory receptors: body sensations

• special sensors: vision, taste, hearing, olfaction

somatosensors

• exteroceptors: sensation of stimuli from outside the body

• interoceptors: sensation of internal body functions

exteroceptors

• mechanoreceptors: touch, pressure on skin, stretching, kinesthesia

• thermoreceptors: sensation of cold and heat

• chemoreceptors: presence of chemical stimulus, but are only taste and smell

special senses

• visual: photosensor (retinal cell in posterior eye)

• olfactory: chemoreceptors in mucous membrane of nasal cavity

• gustory: chemoreceptors found in papillae in lingual epithelia (taste receptors)

• audition

  • hearing: mechanoreceptor, the hair cell

  • vestibular: mechanoreceptor, crista ampullaris and otolith organs