Sensory Systems Flashcards
Dorsal root ganglion
Collection of cell bodies of the afferent sensory fibers
Dorsal root contains
Sensory fibers from the skin subcutaneous and deep tissue and viscera
Afferent nerves
Sensory nerves
Efferent nerves
Motor nerves
Cutaneous joint and visceral afferent nerves are
Myelinated
Perception
The integration of sensory impressions into psychologically meaningful information
Sensory integration
The ability to use sensory information efficiently
Combining several sensory inputs to produce a desired movement
Mechano receptors
Touch pressure vibration proprioception
Thermoreceptors
Heat and cold
Nociceptors
Pain receptors
Somatosensory system
Provides sensory info about the body
Interoception
Perception of sensation from inside the body
Proprioception
Perception of one’s body in space
Order of sensory system development
Touch->vestibular->smell->hearing->vision->taste->proprioception
What system develops in utero
Touch
Muscle spindles and golgi tendons (proprioception receptors) are developed when ?
Are developed by mid fetal life
At 7 weeks in utero
Fetus responds to touch around mouth
At 12 weeks in utero
Muscle spindles formed
At 16 weeks in utero
Golgi tendons organs are formed
At 17 weeks in utero
Cutaneous sensations spreads to entire body
Sensory system maturation
Inc. Nerve conduction velocity
Redistribution of axon branching
Increased synaptic efficiency
At what age do muscle spindles mature
3 years of age
Between what ages do proprioception abilities mature ?
5-12 yrs
When is the sensory system the keenest
Adolescence to early adulthood
Reaction time peaks in mid 20s and slows down
20% during middle adulthood
Why do the cutaneous receptors become less precise when we age ?
Because the skin becomes dry and less elastic
Aging on the somatosensory system
Dec. In number of sensory neurons
Dec. In function of remaining sensors
Arthritic changes affect the ability of joint receptors to detect motion
What percentage of innervation to the peripheral nerves would be classified as peripheral neuropathy ?
30%
Saccades
Quick simultaneous movement of both eyes in the same direction
Slow pursuit of tracking
Slow smooth eye movements
Allow the eyes to closely follow moving objects
Vestibular ocular reflex
Reflex eye movements that stabilize images on the retina
Produces eye movement in opposite direction to head movement
Convergence
Eyes rotate towards each other
Divergence
Eyes rotate away from each other
Prenatal visual system
4th week the eye forms
13th week myelination begins
6th month of gestation reflexive eye blinking
Visual development occurs
After birth
Newborns vision
Initially see in black and white
Have 20/800 vision
At what distance do babies see best and what pattern preference do they have
7-9 in away and their favorite pattern preference is human face
Binocular vision matures between what months ?
3-5 months
Adult like binocular vision occurs by when ?
2 yrs
20/20 vision is achieved by when ?
12 months of age
Between what ages are highly dependent in visual feedback for upright postural control and balance
4-6 yrs
At what age does adult level depth perception occur ?
12 yrs
Visual system adolescence
Eye hand coordination and perception action coupling
Most rapid decline of vision occurs between what ages ?
60-80 yrs
At what age does presbyopia develop ?
45 yrs
What percent of adults over 65 have develop cataracs
60 %
What percent of adults have macular degeneration over 75 ?
28%
Otolith organs
Perceived linear acceleration both horizontally and vertically
Semicircular canals
Detect angular acceleration in three dimensional space
The vestibular system develops from what type of gestational cell ?
Ectoderm
Vestibular system infancy and childhood
Vestibular system completely myelinated at birth
Rocking and spinning contribute to dev of vestibular system
At what month does the vestibular ocular reflex occur
By 2 months of age
Full maturity of the vestibular system is achieved between what ages ?
10-14 yrs
Vestibular visual and somatosensory system coordinate to control what ?
Balance
By what age do we develop static balance ?
9-12yrs
By what age do we develop dynamic balance
12 yrs
When do age related changes to the vestibular system occur ?
40 yrs
