sensory system Flashcards
What are the two types of receptors?
Nerve Cell
Specialized epithelial cell
What are the sensory pathways?
They describe the type and location of the sensory stimulus
Type: dependent on what type of receptor is activated
Location: each receptor has a specific location on the sensory map in the brain
What is dorsal root ganglion? What does it contain? What is mylelinated?
A collection of cell bodies of the afferent sensory fibers
The dorsal roots contain sensory fibers from the skin, subcutaneous and deep tissues, and viscera
Cutaneous, joint, and visceral afferents are composed of mylienated
Central nervous system perception? Sensory maps? Sensory integration?
Perception- the integration of sensory impressions into psychologically meaningful information
Sensory maps- the location of sensory receptors in the brain
Sensory integration- the ability to use information efficiently
What systems are involved in stable standing?
Somatosensory system (proprioception)
Vision
Vestibular system
What are the 3 different types of receptors?
- Mechanoreceptors- touch, pressure, vibratior, proprioception
- Thermoreceptors- heat and cold
- Nociceptors (non mylienated)- pain
What is the order of sensory system development? What is the first system to function in utero?
Touch - vestibular- smell- hearing- vision- taste- proprioception
Touch is first
Maturation of Sensory system during infancy and childhood
All sensory systems are ready to function at birth
Peripheral nerves are completely myelinated
Complete maturation occurs through increased nerve conduction velocity
Redistribution of axon branching
Increased synaptic efficiency
Proprioception at infancy and childhood?
Used very early at birth
Acuity for movements improves between age 5-12
Maturation of adolescence
Sensory system is keenest during late adolescence into early adulthood
Maturation of adulthood
Sensory function begins to decline in adulthood
Reaction time peaks in mid 20 then slows by 20% during middle adulthood
A loss up to 30% of sensory fibers innervating peripheral receptors leads to
Peripheral neuropathy
Arthritic changes affect ability to?
Of joint receptors to detect joint motion
Importance of the visual system?
Dominant sensory modality in humans
Vital to posture, locomotion, balance, and hand function
Visual system prenatal?
Derived from the thalamus in diancephalon
Most peripheral structure develops into the eyeball
4th week- eye forms
13th week- myelination begins
Visual acuity for newborns and what do they see? Best distance for fixation?
20/800
Initially see black and white
Best distance for fixation is 7-9 inches
Maturation for infancy and childhood at 2 months?
2 months: see 2 colors red and yellow and track vertically horizontally and circular path
4 months: binocular vision between 3-5 months, adult like happens at 2 years old
12 months: adult levels of visual acuity achieved 20/20
Children between 4-6 years old are highly dependent on visual feedback for
Upright postural control and balance
When do cataracts form?
Form in individuals over 30
What happens after age 40 in terms of vision?
Decline in ability to quickly adapt from light to dark
What happens at age 45 in terms of vision?
Far sightedness develops
Visual system in older adults?
More light required to see decreased ability to adapt from dark to light
Intrastate sensitivity decreases between 65-75 percent and
Vestibular system prenatal?
Vestibular structures begin as a thickening of the ECTODERM within the ear in the 4th week of gestation
As fetus in utero, vestibular apparatus provides information about that movement.
Is vestibular system completely myelinated at birth?
Yes
When is the normal vestibular ocular reflex present infancy and childhood?
2 months of age
Maturation of vestibular system adolescence? At 9-12 yrs old gain? At 12 yrs old gain?
Full maturity of vestibular system achieved between 10 and 14 yrs of age
9-12 yrs- gain in static balance
12 yrs- gains in dynamic balance
Maturation of adulthood vestibular system
Changes begin at 40 years old, decreased number of sensory cells and nerve fibers in the peripheral nervous system
Neural changes possible in vestibular nerve
Vestibular system in older adults, common issues at 50? Issues for over 70 yrs old?
Decline in function with aging
At 50: dizziness and vertigo
At 70: 40% reduction in hair cells and 36% reduction in peripheral nerve fibers
