Quizz for 11/21/13 Flashcards
respond to
- touch,
- pressure,
- vibration,
- stretch,
- and itch
STIMULUS TYPE
Mechanoreceptors
sensitive to changes in temperature
-within a range
STIMULUS TYPE
Thermoreceptors
Respond to light energy
-retina in the eye
STIMULUS TYPE
Photoreceptors
Respond to chemicals
- smell,
- taste,
- changes in blood chemistry
STIMULUS TYPE
Chemoreceptors
Sensitive to pain-causing stimuli
- extreme heat or cold
- excessive pressure
- inflammatory chemicals
STIMULUS TYPE
Nociceptors
- Respond to stimuli arising outside of body
- Found near the body surface (skin)
- -Sensitive to touch, pressure, pain and temperature
- –ex: Merkel disc, Pacinian Corpuscle, Free nerve endings
- Include the Special Sense Organs
- -eye, ear, nose, taste buds
LOCATION TYPE
Exteroceptors
- AKA: Enteroceptors, Visceroceptors
- Respond to stimuli arising WITHIN the body
- -Found in internal viscera and blood vessels
- Sensitive to chemical changes, smooth muscle stretch, and core temperature changes
- -ex: baroreceptors (blood pressure), and chemoreceptors (CO2 and H+)
LOCATION TYPE
Interoceptors
- Respond to degree of stretch of the associated structures
- -found in: skeletal muscles, tendons, joints, ligaments, connective tissue coverings of bones and muscles
- Continuously inform the brain of one’s movements and position in space
- -Ex: Muscle spindles; Golgi tendon organ
LOCATION TYPE
Proprioceptors
Receptors classified as either:
- Simple
- or Complex
STRUCTURAL COMPLEXITY
- General sensory receptors
- include encapsulated and nonencapsulated varieites
STRUCTURAL COMPLEXITY
Simple
Simple receptors with free dendritic endings, include
- Thermoreceptors
- Nociceptors
- Light touch receptors
ex: free nerve endings, Merkel discs, root hair plexus
STRUCTURAL COMPLEXITY
Simple - Nonencapsulated
(10º - 40º C), found in superficial dermis
STRUCTURAL COMPLEXITY
Cold Thermoreceptor (Simple Nonencapsulated)
(32º - 48º C); found in deeper dermis
STRUCTURAL COMPLEXITY
Heat Thermoreceptor (Simple Nonencapsulated)
Respond to
- pinching,
- inflammatory chemicals from damaged tissue,
- temperature changes outside the range of the thermoreceptors,
- Capsaicin
STRUCTURAL COMPLEXITY
Nociceptors (Simple Nonencapsulated)
Receptors include:
- Merkel discs (light pressure),
- Hair follicle receptors (light touch)
STRUCTURAL COMPLEXITY
Light Touch Receptors (Simple nonencapsulated)
Simple receptors that ALL respond as mechanoreceptors ex: Meissner corpuscles Pacinian corpuscles Ruffini Endings
Encapsulated - Simple
Structural Complexity
-discriminative touch
Meissner’s Corpuscles
Encapsulated - Simple
Structural Complexity
deep pressure and vibration
Pacinian (lamellated) corpuscles
Encapsulated - Simple
Structural Complexity
deep continuous pressure
Ruffini endings
Encapsulated - Simple
Structural Complexity
Muscle stretch
Muscle Spindles
Encapsulated - Simple
Structural Complexity
Muscle load
Golgi tendon Organs
Encapsulated - Simple
Structural Complexity
Stretch in synovial joint capsules
Joint kinesthetic receptors
Encapsulated - Simple
Structural Complexity
Special Sense organs have ___ complexity
- Organization is specific to special sense organ and is polysynaptic
- Involve with:
- -vision
- -hearing
- -equilibrium
- -smell
- -taste
Complex receptors
Complex receptors
Structural Complexity
- cornea
- aqueous humor
- lens
- vitreous humor
- neural layer of retina
- photoreceptors
Pathway of light entering the eye
majority of light refraction occurs at ____
cornea
but light refracts in these three places
- entering the cornea
- entering the lens
- exiting the lens
___ muscle alters lens curvature and shape to allow for fine focusing of an image
ciliary
ciliary body is attached to lens via ___
suspensory ligaments
light from a distance needs ___ refraction for proper focusing
very little
FOCUSING FOR DISTANCE VISION
the distance beyond which the lens does not need to change shape to focus
-is 20 feet in the emmetropic (normal) eye
Far Point of Vision
FOCUSING FOR DISTANCE VISION
normal eye
emmetropic
Distance vision requires (parasympathetic/sympathetic) input
sympathetic
FOCUSING FOR DISTANCE VISION
Ciliary muscles are (relaxed/taut), meaning the suspensory ligaments are (relaxed/taught) so the lens remains (flat/round) for DISTANCE vision
RELAXED ciliary muscle
TAUT suspensory ligaments
=flattened lens
FOCUSING FOR DISTANCE VISION
Light from a close object (converges/diverges) as it approaches the eye and requires active adjustments to place image at the fovea focal point
Diverges
FOCUSING FOR CLOSE VISION
=the closest point at which we can focus clearly. representing the maximum lens bulge achieveable
= Near point of vision
FOCUSING FOR CLOSE VISION
What is the near point of vision for an emmetropic eye?
4 inches
What are the three required simultaneous responses for close vision?
- Accommodation
- Constriction
- Convergence
FOCUSING FOR CLOSE VISION
=changing the lens shape by ciliary muscles; increases refraction
= Accommodation
FOCUSING FOR CLOSE VISION
Close vision requires (parasympathetic/sympathetic) input
Parasympathetic
FOCUSING FOR CLOSE VISION
- Ciliary muscles are (relaxed/taut), meaning the suspensory ligaments are (relaxed/taught) so the lens remains (flat/round) for CLOSE vision
Ciliary muscles taut
Suspensory ligaments loose
Lens becomes rounder
1. Accomodation
FOCUSING FOR CLOSE VISION
- =the pupillary reflex (constricts/relaxes) the pupils to prevent the most divergent light rays from entering the eyes for close vision
CONSTRICTS
=Constriction
FOCUSING FOR CLOSE VISION
- (Medial/Lateral) movement of the eyeballs toward the object being viewed for close vision
Convergence.
-Medial
FOCUSING FOR CLOSE VISION
-normal eyeball length and eye function with light focused properly
Emmetropic Eye
PROBLEMS OF REFRACTION
- the FOCAL POINT is in FRONT of the retina due to a longer than normal eyeball
- difficulty with distant vision
- corrected with CONCAVE lens
Myopia (Nearsightedness)
PROBLEMS OF REFRACTION
- The FOCAL POINT is BEHIND the retina due to a shorter than normal eyeball
- difficulty with close vision
- corrected with convex lens
Hyperopia (Farsightedness)
PROBLEMS OF REFRACTION
- caused by unequal curvatures in different parts of the cornea or lens
- corrected with cylindrically ground lenses, corneal implants, or laser procedures
Astigmatism
PROBLEMS OF REFRACTION
the awareness of changes in the internal and external environment
Sensation
The conscious interpretation of those stimuli
Perception
Input comes from exteroceptors, proprioceptors, and interoceptors
Sensory Integration
Input is relayed toward the brain but is processed along the way
-Known as ___
Ex: processing in the thalamus
Sensory Integration
Sensory integration involves processing at three levels
- Receptor
- Circuit level
- Perceptual level
sensory receptors
Receptor Sensory Integration
Ascending pathways
Circuit Level Sensory Integration
Neuronal Circuits in the Cerebral Cortex
Perceptual Level Sensory Integration
To be processed at the receptor level,
The receptor must have ___y for the stimulus energy
specificity
To be processed at the receptor level, The receptor’s ___ (area the receptor monitors) must be stimulated
receptive field
Stimulus energy must be converted into a graded potential=
Transduction
Processing at the Receptor Level
___ occurs when sensory receptors are subjected to a constant, unchanging stimulus
Adaptation (of Sensory Receptors)
Over time,
- Receptor membranes become less responsive
- Graded potentials decline in frequency or stop
Adaptation of Sensory Receptors
___ receptors signal the beginning or end of a stimulus, thus fast-adapting
Examples: receptors for pressure, touch and smell
Phasic receptors
___ receptors are slow-adapting or non-adapting
Tonic receptors
Slow-adapting examples of ___ receptors: Merkel discs, Ruffini endings and chemoreceptors
Tonic receptors
Non-adapting examples of ___ receptors: Pain receptors and proprioceptors
Tonic receptors
In general sense receptors, the ___ potential and ___ potential (AP generator) arethe same thing
receptor potential; graded potentials
Stimulus —> Receptor potential (graded potential –> ?
General Sense Receptors Action Potential (if threshold is reached)
In SPECIAL SENSE organs, there’s intermediate step involving release of neurotransmitter. This is example of ___
Polysynaptism
For Special Sense Organs,
- Stimulus
- Receptor Potential (in receptor cell)
- ??
- Release of Neurotransmitter
For Special Sense Organs,
- Release of Neurotransmitter
- ??
- Graded Potential
For Special Sense Organs,
- Graded Potential
- ???
- ACtion Potential (if threshold is reached)
Pathways of 3 neurons conduct sensory impulses upward to the appropriate brain regions
Processing at the Circuit Level
Conduct impulses from the receptor level to the second-order neurons in the CNS
First order neurons
Processing at the Circuit Level
Transmit impulses to the thalamus or cerebellum
Second order neurons
Processing at the Circuit Level
Conduct impulses from the thalamus to the somatosensory cortex
Third order neurons
Processing at the Circuit Level
- Sensation is detected in the primary cortex related to sensory pathway
Processing at the Perceptual Level (Cerebral cortex circuits)
-Perception (conscious interpretation) in the related association cortex
Processing at the Perceptual Level (Cerebral cortex circuits)
Identification of the sensation depends on the specific location of the target neurons in the appropriate ___ cortex
sensory
conscious interpretation
Perception
Perception occurs in the related association cortex and involves
1)
2)
3)
1) Perceptual detection
2) Magnitude estimation
3) Spatial discrimination
Ability to detect a stimulus (requires a summation of impulses)
Perceptual Detection
intensity is coded in the frequency of impulses
Magnitude estimation
Identifying the site or pattern of the stimulus (studied by the two-point discrimination test0
Spatial discrimination
warns of actual or impending tissue damage
Perception of Pain
stimulus intensity where pain is first sensed by the brain
Pain threshold
Stimuli include extreme pressure and temperature, inflammatory chemicals
Pain threshold
Most potent stimuli for this are: histamine, K+, ATP, acids and bradykinin
pain threshold
Impulses for pain travel on fibers that release neurotransmitters ___ & ___
Glutamate
Substance P
individual, highly variable
pain tolerance
Blocked by inhibitory endogenous opioids (endorphins and enkephalins)
Pain Modulation
is often difficult yet critical to positive post-injury / post-op outcomes
Effective Pain Management
-can occur secondary to intense or prolonged pain
Chronic Pain
-Due to spinal cord pain amplification; must reduce signals to prevent synapse enhancement
Chronic Pain
-When the stimuli at the end of the remaining stump travels up the afferent pathway and terminates in the region of the sensory cortex mapped from the original body part
Phantom Limb Pain
follows amputation
The body part is missing, but the pathway is the same, so the brain interprets the part as present
Phantom Limb Pain
Improved by using epidural anesthesia which blocks spinal cord transmission
Phantom Limb Pain
Pain stimuli arising from the viscera are perceived as somatic in origin
Referred Pain
Visceral pain afferents travel along the same pathways as somatic pain fibers
Referred Pain
70% of all the body’s sensory receptors are in the
eye
Almost half of the cerebral cortex is involved in processing
visual information
Most of the eye is protected by a cushion of ___ and the ___
fat;
bony orbit
- Eyebrows
- Eyelids (Palpebrae)
- Conjunctiva
- Lacrimal Apparatus
- Extrinsic Eye Muscle
Protect the eye
Aid in Eye Function
Accessory Structures of the Eye
Coarse hairs that overlie the supraorbital margins;
shade and stop perspiration
Eyebrows
Palpebrae
Eyelids
Protect the eye anteriorly
Palpebrae
separates eyelids
Palpebral fissure
Elevation at medial commissure;
contains oil and sweat glands
Lacrimal caruncle
Internal supporting connective tissue sheet for muscle attachment
Tarsal Plates:
This muscle closes the eye
Orbicularis oculi muscle
This muscle opens the eye
Levator Palpebrae Superioris
lubricating modified sebaceous glands
Tarsal Glands
initiate reflex blinking
Eyelashes