Exam #5 Chapter 16 Flashcards
- a unique type of sensation
- a neuron can only carry info of one modality
sensory modality
-2 general senses:
somatic and visceral
-tactile, thermal, pain, and proprioception are ______ senses
somatic
-pressure, stretch, chemicals, nausea, hunger, and temp are _______ senses
visceral senses
-small, taste, vision, hearing, equilibrium, and balance are ______ senses
special senses
- stimulation of sensory receptor
- transduction of the stimulus
- generation of nerve impulses
- integration of sensory input
-steps of the ______
process of sensation
-sensory receptor converts the energy in the stimulus into a graded potential, a process called ______
transduction
-there are 3 different classification methods used to describe sensory receptors:
structure, location, and stimulus type
- bare dendrites associated with pain, thermal, tickle, itch, and some touch sensations
- nonencapaulated structure
free nerve ending
-dendrites encloses in a connective tissue capsule for pressure, vibration, and some touch sensation
encapsulated nerve endings (structure)
- receptor cells synapse with first-order sensory neurons
- located in retina of eye, inner ear, and taste buds
separate cells (structure)
- located at or near body surface
- sensitive to stimuli originating outside the body, provide information about external environment
- convey visual, smell, taste, touch, pressure, vibration, thermal, and pain
exteroceptors
- located in blood vessels, visceral organs, and nervous system
- provide information about the internal environment
- impulses usually are not consciously perceived but occasionally may be felt as pain or pressure
interceptors
- located in muscles, tendons, joints, and inner ear
- provide information about body position, muscle length and tension, position and motion of joints, and equilibrium
proprioceptors
- detect mechanical stimuli, provide sensations of touch, pressure, vibration, perception, and hearing and equilibrium
- also monitor stretching of blood vessels and internal organs
mechanoreceptors
- detect changes in temperature
- free nerve endings in skin and mucous membranes of mouth, vagina, and anus
- have warm and cold receptors
- adaptation is initially rapid, then slow
thermoreceptors
- respond to painful stimuli resulting from physical or chemical damage to tissue
- found in every tissue except for the brain
- free nerve ending
- slow adaptation rate
- fast and slow pain
nociceptors
-detect light and strikes the reruns of the eye
photoreceptors
-detect chemicals in mouth, nose, and body fluids
chemoreceptors
-sense osmotic pressure of body fluids
osmoreceptors
-include touch, pressure, vibration, itch, and tickle, these are ______ sensations
tactile
- type I cutaneous mechanoreceptors (tactile disc)
- meissner’s (corpuscles of touch)
- type II cutaneous mechanoreceptors (ruffini corpuscle)
- hair root plexus
- lamellated corpuscle (pacinian)
tactile sensations
- capsule surrounds mass of dendrites in dermal papillae of hairless skin
- onset of touch and low frequency vibrations
- rapid adaptation rate
corpuscles of touch (Meissner corpuscles)
- free nerve endings wrapped around hair follicles in skin
- movements of skin surface that disturb hairs
- rapid adaptation rate
hair root plexus
- saucer shaped free nerve endings make contact with tactile epithelial cells in epidermis
- continuous touch and pressure
- slow adaptation rate
type I cutaneous mechanoreceptors (tactile disc)
- elongated capsule surrounds dendrites deep in dermis and ligaments and tendons
- skin stretching and pressure
- slow adaptation rate
type II cutaneous mechanoreceptors (Ruffini corpuscles)
- oval layered capsule surrounds dendrites
- present in dermis and subcutaneous layer, submucosal tissues, joints, periosteum, and some viscera
- high frequency vibrations
- rapid adaptation rate
lamellated corpuscles (pacinian)
- free nerve endings in skin and mucous membranes
- itching and tickling
- slow and rapid adaptation rate
itch and tickle receptors
-muscle spindles, tendon organs, joint kinesthetic receptors are _______
proprioceptors
- sensory nerve endings wrap around central area of encapsulated intrafusal muscle fibers within most skeletal muscles
- muscle length sensations
- slow adaptation rate
muscle spindles
- capsule encloses connective tissue wrapped in sensory nerve endings at junction of tendon and muscle
- muscle tension sensation
- slow adaptation
tendon organs
- lamellated corpuscles, type II cutaneous mechanoreceptors, tendons organs and free nerve endings
- joint position and movement sensation
- rapid adaptation
joint kinesthetic receptors
-the frequency of impulses decreases during a constant maintained stimulus
adaptation
-felt within 0.1 sec, acute, sharp, not felt in deeper tissues
fast pain
-felt after a second or more, burning, chronic, throbbing
slow pain
-pain is felt in or just deep to the skin that overlies the stimulated organ, or in a surface area far from the stimulated organ
referred pain
- these pathways relay info from sensory receptors to the somatosensory area of the cerebrum and to the cerebellum
- has thousands of sets of 3 neurons, the first, second, and third order
somatic sensory pathways
- are sensory neurons that conduct impulses from somatic sensory receptors into the brain stem or spinal cord
- brings info to CNS
first order neurons
- conduct impulses from the brain stem or spinal cord to the thalamus
- axons decussate in the spinal cord or brain stem
second order neurons
-from thalamus to the somatosensory area on the same side
third order neurons
- touch, pressure, vibration, proprioception from limbs, trunk, neck, and posterior head
- has two tracts: gracile fasiculus and cuneate fasiculus, each tract has its nucleus in the medulla
- has medial lemniscus
posterior column medial lemnicus pathway
-tract of the lower trunk and limbs
gracile fasiculus
-track of the upper limbs and trunk, neck, and head
cuneate fasiculus
- surrounding muscle spindles are ordinary (normal) skeletal muscle fibers called ______
- supplied by ______
extrafusal muscle fibers
alpha motor neurons
-wrapped in sensory neurons and detect the tension of the muscle
infrafusal fibers
-during contraction the _______ causes the intrafusal fibers to contract as well, maintaining their tension
gamma motor neuron
- axons of the second order neurons cross to the opposite side of the medulla and enter the _______
- thin projection from medulla to thalamus
medial lemniscus
- pain, temp, itch, and tickle from the limbs, trunk, neck and posterior head
- 2 spinal cord tracts: anterior and posterior
- 2nd order neurons are decussating in the spinal cord instead of the brain stem
anterolateral (spinothalamic) pathway
-the 3 pathways for nerve impulses entering the spinal cord:
•ascend on the same side
•cross the spinal cord and then ascend, or exit via the reflex arc
*in the _____, the 2nd order neurons are decussating in the spinal cord instead of the brain stem
anterolateral (spinothalamic) pathway
- most somatic sensations (tactile, thermal, pain) in the face, nasal/oral cavities, and teeth ascend via this pathway
- some incoming first order neurons actually descend to the medulla before synapsing with the second order neurons and crossing over
trigeminothalamic pathway
- convey nerve impulses from proprioceptors in trunk and lower limb of one side of the body to same side of cerebellum
- proprioceptive input informs cerebellum of actual movements, allowing it to coordinate, smooth, and refined skilled movements and maintain posture and balance
- posterior column-medial lemniscus pathway=conscious proprioception (cerebrum)
- spinocerebellar pathways=not consciously perceived (cerebellum)
anterior and posterior spinocerebellar pathways (spinocerebellar tracts )
-neurons that exit the brain stem and spinal cord to inner age skeletal muscles
lower motor neurons (LMN)
- can refer to those from brain stem or cerebral cortex
- those from the brain stem regulate posture, balance, muscle tone, reflexes
upper motor neurons (UMN)
-initiate and terminate movements, prevents unwanted movements
basal nuclei
-evaluate the difference between intended and performed actions
cerebellum
-3 direct pyramidal pathways are:
lateral cortical spinal
anterior cortical spinal
corticobulbar pathway
- descend through internal capsule in the brain and the cerebral peduncle of the midbrain
- voluntary movements
- 90% decussate in the pyramids of the medulla
direct pyramidal motor pathway/lateral corticospinal payhway
- controls incredibly precise movements in the distal parts of the limbs
- like typing, fine movement
- innervates skeletal muscles
lateral corticalspinal pathway
- the remaining 10% of UMN’s that descend through the capsule and peduncle do not decussate until reaching the spinal cord, in the anterior white commissure
- controls the trunk and proximal parts of the limbs
- gross movements
anterior corticospinal pathway
- descend through internal capsule in the brain and the cerebral peduncle of the midbrain
- axons terminate on 9 of 12 cranial nerves (I, II, VIII are sensory ONLY)
- controls all the voluntary movements of the face, eyes, tongue, neck (head)
- goes through mid brain
corticobulbur pathway
-all motor tracts other than corticospinal and corticobulbular are _____
indirect extrapyramidal motor pathways
- rubrospinal
- tectospinal
- vestibulospinal
- lateral reticulospinal
- medial reticulospinal
indirect extrapyramidal motor pathways
- induct AP to cause involuntary movements that regulate posture, balance, muscle tone, and reflexive movements of the head and trunk
indirect motor pathways
-conveys nerve impulses from red nucleus (which receives input from cerebral cortex and cerebellum) to contralateral skeletal muscles that govern precise, voluntary movements of distal parts of upper limbs
rubrospinal pathway
-conveys nerve impulses from superior colliculus to contralateral skeletal muscles that reflexively move head, eyes, and trunk in response to visual or auditory stimuli
tectospinal pathway
-conveys nerve impulses from vestibular nucleus (which receives input about head movements from inner ear) to ipsilateral skeletal muscle of trunk and proximal parts of limbs for maintaining posture and balance in response to head movements
vestibulospinal pathway
-conveys nerve impulses from reticular formation to ipsilateral skeletal muscles of trunk and proximal parts of limbs for maintaining posture and regulating muscle tone in response to ongoing body movements
lateral and medial reticulospinal pathways
