Lecture 3 Flashcards
Sensory
What is the order in which the events in the sensory system occur?
receptors, sensory pathways, central nervous system, motor system
What are the two types of receptors?
1) Nerve cell
2) specialized epithelial cell
sensory pathways describe the _________ and _________ of the sensory stimulus
type and location in the brain (ex: spinoreticular tract)
What is a dorsal root ganglion?
a collection of cell bodies of the afferent sensory fibers
Which functions do the dorsal roots contain?
sensory fibers from the skin, subcutaneous and deep tissues, and viscera
cutaneous, joint, and visceral afferents are composed of ___________ (mylelinated/unmyelinated)
myelinated (conduction is faster)
What is perception?
the integration of sensory impressions into psychologically meaningful information
What is sensory integration?
The ability to use sensory information efficiently EX: combining several sensory inputs to produce a desired movement
What systems are involved in stable standing balance?
somatosensory system (proprioception), vision, and vestibular
What are the three types of receptors in the somatosensory system and what are they responsible for?
1) mechanoreceptors (touch, pressure, vibrator, proprioception)
2) thermoreceptors (hot and cold)
3) nociceptors (pain)
what is exteroception?
the cutaneous sensation of touch from specialized epithelial cells (somatosensory system)
interoception
perception of sensation from inside the body (heartrate, respiratory, and GI)
proprioception
perception of one’s body in space
what is the order of sensory system development in prenatal?
touch, vestibular, smell, hearing, vision, taste, proprioception
when does a fetus respond to touch around mouth?
7 weeks
When are the muscle spindles formed in a fetus?
12 weeks
when are golgi tendon organs formed?
16 weeks
When does cutaneous sensation spread to the entire body?
17 weeks
What maturational changes occur to the somatosensory system throughout childhood
- increased nerve conduction velocity
- redistribution of axon branching
- increased synaptic efficiency
Which reflex is an example of touch developing in infancy in childhood?
rooting reflex (used to find food)
when does specific touch localization occur in infancy / childhood?
12-16 months
when are infants/children able to identify objects by touch?
5 years
when does two-point discrimination develop in infants / children?
7 years
What is the earliest muscle spindles mature?
3 years old
what is an example of how proprioception is used in infants very early after birth?
imitation, reaching, and locomotion
When does proprioceptive acuity for movments improve in infants and children?
between age 5-12
when is the sensory system keenest?
late adolescence into early adulthood
What happens to sensory function in adulthood?
It begins to decline (specifically in middle age)
when does reaction time peak? When and by how much does it slow?
peaks in mid-20’s and slows by 20% during middle adulthood
There is a gradual decline in sensory function while aging characterized by….. (name 3 events)
- decrease in the number of sensory neurons
- decrease in functioning of remaining sensory neurons
- structural and physiological changes within the CNS
a loss of up to ______ of sensory fibers innervating peripheral receptors leads to peripheral neuropathy in aging
30%
Name 4 functional consequences of a age-related changes to the sensory system
- postural instability
- balance problems
- diminished fine motor coordination
What three things does vision provide individuals information about?
1) the external world
2) identification of external objects and determination of their movement
3) where the body is in space, the relationship of one’s body parts, and the motion of one’s body
How many extraocular muscles are there?
6 muscles
What are the 4 types of head movements controlled by the extraocular muscles?
saccades, slow pursuit or tracking, vestibulo-ocular reflect (VOR), vergence
sarcades definition
quick, simultaneous movement of both eyes in the SAME direction
slow pursuit / tracking
slow, smooth eye movements; the eyes closely follow a moving object (DUI test)
vestibulo-ocular reflex (VOR)
reflex eye movement that stabilizes images on retina; produces eye movement in opposite direction to head mvoement
vergence
simultaneous movement of both eyes in opposite directions; convergence = towards each other divergence = away from each other
When in prenatal does the eye form?
4th week
When does myelination of visual nerves begin during prenatal stages?
13th week
When in gestation is there reflexive eye blinking?
6 months
What is a newborns visual acuity?
20/800
What colors can a baby see at 2 months?
red and yellow
When does perception of form develop in infancy / childhood?
3 months
When is full color vision achieved in infants / children?
4 months
When is adult levels of visual acuity achieved?
12 months
development of eye-hand coordination and perception-action coupling occurs in what stage of life?
adolescence
when are adult levels of depth perception achieved?
12 years old
does vision increase/decrease/remain stable in your 20’s and 30’s?
increase
does vision increase/decrease/remain stable in your 40’s and 50’s?
remain stable
does vision increase/decrease/remain stable from 60-80?
rapid decline
cataracts begins to form in individuals over _______
30
When is there a decline in the ability to quickly adapt from light to dark environments?
After age 40
when does presbyopia develop?
45
what is presbyopia?
far-sighted
what does it mean to have an increased visual threshold? When does this occur?
more light is required to see; older age
what is the macula?
allows for retina to make adjustments
what does it mean if field of vision dimishes?
loss of depth perception
when does contrast sensitivity decrease?
between 65-75
Which organs detect linear accelerations?
otolith organs (crystals and cilia in head)
Which organs detect rotational accelerations?
semicircular canals
vestibular structures begin as a thickening of the _________ within the primitive ear in the ________ week of gestation
ectoderm; 4th week
when are the semicircular canals, utricle, and saccule completely formed?
10 weeks
When is the vestibular system completely myelinated?
At birth
When is the normal vestibular ocular reflex present?
by 2 months age
When is there full maturity of vestibular system?
Between 10 and 14 years of age
9-12 years: gains in ______ balance (dynamic /static)
12 yrs: gains in _________ balance (dynamic / static)
static ; dynamic
When doe age-related changes begin occurring in the vestibular system?
40’s
______% reduction in hair cells and _______% reduction in peripheral nerve fibers in adults over 70
40% and 36%
one age-related change is __________ (increased/ decreased) thresholds of excitation of vestibular nuclei
increased
