List the 5 sensory receptors
5 sensory receptors:
Mechanoreceptors
Thermoreceptors
Nociceptors
Electromagnetic receptors
Chemoreceptors
Function of Mechanoreceptors?
Function of Mechanoreceptors:
Detect mechanical compression or stretching of the receptor or of tissues adjacent to the receptor
Function of Thermoreceptors?
Function of Thermoreceptors:
Detect changes in temperature
*just cold and warm, not specific temperatures
Function of Nociceptors?
Function of Nociceptors:
Detect damage occurring in the tissues
Function of Electromagnetic receptors?
Electromagnetic receptors:
Detect light on the retina of the eye
Function of Chemoreceptors?
Function of Chemoreceptors:
Detect taste in the mouth, smell in the nose, oxygen level in the blood, osmolality of the body fluids, and carbon dioxide concentrations
Modality of senation refers to
Sight, touch, hearing, taste, and smell
Labeled Line Principle:
_____ of nerve fibers for transmitting _____ _____ modality of sensation
Each receptor type is _____ specific to one _____ of stimulus
_____ _____ to other types of sensory stimuli
Different modalities of sensation depend on the _____ _____ in the CNS when a nerve fiber is stimulated (e.g. pain, touch, sight, sound)
Labeled Line Principle:
Specificity** of nerve fibers for transmitting **only one modality of sensation
Each receptor type is highly specific to one type of stimulus
Non-responsive to other types of sensory stimuli
Different modalities of sensation depend on the termination point in the CNS when a nerve fiber is stimulated (e.g. pain, touch, sight, sound)
What are the Mechanisms of Receptor Potential?
Mechanisms of Receptor Potential:
Mechanical deformation
Application of a chemical to the membrane
Change of temperature of the membrane
Electromagnatic radiation
receptor potentials:
When receptor potentials rise above _____ in the nerve fiber attached to the receptor, then _____ _____ occur
The more the receptor potential rises above _____ level, the greater the action potential _____
receptor potentials:
When receptor potentials rise above threshold in the nerve fiber attached to the receptor, then action potentials occur
The more the receptor potential rises above threshold level, the greater the action potential frequency
*AP are not graded! Onlytheirfrequency changes!
Adaptation of Receptors:
Adapt partially or completely to a _____ stimulus over _____.
Rapid adaptation and _____ adaptation
Adaptation of Receptors:
Adapt partially or completely to a constant stimulus over time.
(Some sensory receptors adapt to a greater extent than others)
Rapid adaptation and slow adaptation
*Note on image there is a large initial response where it starts lowering right away.
Slow Adapting Fibers versus Fast Adapting Fibers:
Slow Adapting Receptors: detect _____ stimulus strength
Tonic receptors – transmit for many hours
Rapidly Adapting Receptors: detect _____ stimulus strength
Movement receptors
Slow Adapting Fibers versus Fast Adapting Fibers:
Slow Adapting Receptors: detect CONTINUOUS stimulus strength
Tonic receptors – transmit for many hours
Rapidly Adapting Receptors: detect CHANGE IN stimulus strength
Movement receptors
Spatial versus Temporal Summation:
Be able to recognize and understand the concepts
Spatial versus Temporal Summation:
Be able to recognize and understand the concepts
Which figure best represents the response of the most rapidly adapting receptor to the stimulus?
Which figure best represents the response of the most rapidly adapting receptor to the stimulus?
B
Which figure best represents the response of the most slowly adapting receptor to the stimulus?
Which figure best represents the response of the most slowly adapting receptor to the stimulus?
B
*Always keeps you aware of the stimulus
Which of the following statements best describes the receptor potential?
A. The receptor potential is always constant
B. The greater the intensity of the stimulus, the greater the change in receptor potential
C. Any change in the receptor potential will induce an action potential
D. Receptor excitation always involves depolarization of the receptor
Which of the following statements best describes the receptor potential?
B.
The greater the intensity of the stimulus, the greater the change in receptor potential
Which of the following statements concerning the mechanoreceptive potential are true?
A. An increase in stimulus energy results in an increase in receptor potential
B. When receptor potential rises above a certain threshold, action potentials will appear in the neuron attached to the receptor
C. The number of action potentials generated in the neuron attached to the receptor is proportional to the receptor potential
D. All of the above
Which of the following statements concerning the mechanoreceptive potential are true?
D.
All of the above
Which of the following is a characteristic of almost all sensory receptors?
A. The ability to perceive a mechanical force
B. The ability to be modulated by a change in temperature
C. The ability to be excited by the application of a chemical irritant
D. The ability to adapt to the stimulus
Which of the following is a characteristic of almost all sensory receptors?
D.
The ability to adapt to the stimulus
Name 3 Somatic senses:
Somatic senses:
Mechanoreceptive Somatic Sense
Thermoreceptive Sense
Pain Sense
Mechanoreceptive Somatic Sense:
_____ and _____ sensation stimulated by mechanical displacement of the tissue
Touch, pressure, vibration, “_____” senses, and _____ position and rate of movement
Mechanoreceptive Somatic Sense:
Tactile and position sensation stimulated by mechanical displacement of the tissue
Touch, pressure, vibration, “tickle” senses, and static position and rate of movement
Thermoreceptive Sense:
Detect _____ and _____
Thermoreceptive Sense:
Detect heat and cold
Pain Sense:
Activated by _____ _____ _____
Pain Sense:
Activated by damage to tissues
Tactile Receptors:
Understand the difference in the tactile receptors
*6 types we will need to know
(Free nerve endings, Meissner’s corpuscle, Expanded tip receptor, Tactile hair, Ruffini’s endings, Pacinian corpuscle)
Tactile Receptors:
Understand the difference in the tactile receptors
*6 types we will need to know
(Free nerve endings, Meissner’s corpuscle, Expanded tip receptor, Tactile hair, Ruffini’s endings, Pacinian corpuscle)
Free nerve endings
Free nerve endings:
found in skin and tissues
detect touch and pressure
Meissner’s corpuscle
Meissner’s corpuscle:
touch receptor
fingertips
lips
hairy skin
discern spatial locations of touch
Expanded tip receptor
Expanded tip receptor:
fingertips
responsible for steady-state signals
Tactile hair
Tactile hair:
detect slight movement of any hair
assists in detecting movement on surface of body
Ruffini’s endings
Ruffini’s endings:
deep layers of the skin
deep internal tissues
joint capsules (helps detect joint angulation)
signal continuous states of deformation
Pacinian corpuscle
Pacinian corpuscle:
beneath the skin
deep fascial tissues
detect tissue vibration** or **rapid changes in tissue
Sensory Pathways for Transmitting Somatic Signals into the CNS:
All sensory info enters the spinal cord through the _____ roots of the spinal nerves then follow one of two pathways:
What are the two pathways?
Sensory Pathways for Transmitting Somatic Signals into the CNS:
All sensory info enters the spinal cord through the dorsal roots of the spinal nerves then follow one of two pathways:
Dorsal column-medial lemniscal system
or
Anterolateral system
Dorsal column-medial lemniscal system:
Composed of _____ myelinated nerve fibers
Transmit signals to the brain at velocities of ___ - ___ m/sec
_____ _____ of spatial orientation
Dorsal column-medial lemniscal system:
Composed of large myelinated nerve fibers
Transmit signals to the brain at velocities of 30-110 m/sec
High degree of spatial orientation
*example is pain, when the signal needs to reach your brain immediately
Anterolateral system:
Composed of _____ myelinated nerve fibers
Transmit signals to the brain at velocities of ___ - ___ m/sec
_____ _____ of spatial orientation
Anterolateral system:
Composed of smaller myelinated nerve fibers
Transmit signals to the brain at velocities of 2-40 m/sec
Lower degree of spatial orientation
*Example is if your hand remains in the fire, your brain needs a constant reminder!
Dorsal column-medial lemniscal system: has _____ myelinated fibers, a _____ velocity, and a _____ degree of spatial orientation
vs
Anterolateral system: which has _____ myelinated fibers, a _____ velocity, and a _____ degree of spatial orientation
Dorsal column-medial lemniscal system: has large myelinated fibers, a faster velocity, and a high degree of spatial orientation
vs
Anterolateral system: which has smaller myelinated fibers, a slower velocity, and a lower degree of spatial orientation
Dorsal column-medial lemniscal system:
Touch sensations requiring a _____ degree of localization of the stimulus
Touch sensations requiring transmission of _____ gradations of intensity
Phasic sensations, such _____ sensations
Sensations that signal _____ against the skin
_____ sensations from the joints
Dorsal column-medial lemniscal system:
Touch sensations requiring a high degree** of **localization of the stimulus
Touch sensations requiring transmission of fine gradations of intensity
Phasic sensations, such vibratory (change in intensity) sensations
Sensations that signal movement against the skin
Position sensations from the joints
Anterolateral system:
Pain
Thermal sensations, _____ and _____
_____ touch and pressure sensations
Tickle and _____ sensations
S____ sensations
Anterolateral system:
Pain
Thermal sensations, warmth and cold
Crude (non-specific) touch and pressure sensations
Tickle and itch sensations
Sexual sensations
Be aware of the basic locations where different body areas are represented in the somatosensory area
Be aware of the basic locations where different body areas are represented in the somatosensory area
Be aware of the basic differences of the somatosensory area size in realtion to the receptor quantity
Be aware of the basic differences of the somatosensory area size in realtion to the receptor quantity
2 point discrimination
2 point discrimination:
the length required to activate 2 receptors with stimuli
Lateral Inhibition
Lateral Inhibition:
One receptors axons branches into 2 synapses
1) Normal excitatory synapse → excitation
2) an 2nd excitatory synapse releases a different neurotransmitter that inhibits other nearby synapses (preventing their excitation from the initial stimuli)
***allows spacial orientation of stimuli***
Tactile Receptors:
All involved in detection of _____
Different receptors detect different _____ of _____
Pacinian corpuscles detect ?
Meissner’s corpuscles detect ?
_____ signals transmitted only in the dorsal column pathway
Tactile Receptors:
All involved in detection of vibration
Different receptors detect different frequencies of vibration
Pacinian corpuscles detect high-frequency vibrations* from 30 to 800 cycles per second
Meissner’s corpuscles detect low-frequency vibrations* from 2 up to 80 cycles per second
Vibration signals transmitted only in the dorsal column pathway
*All detect vibration, but the frequency activates the specific receptors
Proprioception senses include:
Part of which pathway?
Static _____ senses (_____ adapting)
_____ of _____ senses (dynamic proprioception; _____ adapting)
Proprioception senses include:
Dorsal column-medial lemniscus pathway
Static position senses (slow adapting)
Rate of movement senses (dynamic proprioception; rapid adapting)
Mechanosensitive proprioceptors:
Part of which pathway?
Muscle spindles (muscle _____ receptors)
Golgi tendon organs (measure muscle_____)
Ruffini, Golgi, Pacini, Free nerve endings (_____)
Mechanosensitive proprioceptors:
Dorsal column-medial lemniscus pathway
Muscle spindles (muscle stretch receptors)*
Golgi tendon organs (measure muscle tension)*
Ruffini, Golgi, Pacini, Free nerve endings (joint)**
*Golgi and spindles static as long as strecth or tension is present; slow adapting
**Found in specific joints; rapid adapting; for rate of movement
Understand somatosensory projections, tracts, and receptors for the:
Dorsal column-medial lemniscus pathway (_____ceptors or _____ceptors)
and the
Anterolateral pathway (_____ceptors or _____ceptors)
Understand somatosensory projections, tracts, and receptors for the:
Dorsal column-medial lemniscus pathway (Proprioceptors or mechanoreceptors)
and the
Anterolateral pathway (Nociceptors or thermoreceptors)
Thermoreceptors:
Receptors located in _____ _____
Receptors specific to ?
_____ receptors begin firing above ?
_____ receptors begin firing below ?
Thermoreceptors:
Receptors located in the skin
Receptors specific to either hot or cold
Warm receptors begin firing above 30 degrees Celsius (86 F)
Cold receptors begin firing below 24 degrees Celsius (75.2 f)
Tickle and Itch Detection:
Part of which pathway?
_____ nerve ______ found in the _____ _____ of the skin
Tickle and Itch Detection:
Anterolateral pathway
Free nerve endings found in the superficial layers of the skin
Pain:
Part of which pathway?
Fast pain: is felt within _____ after a pain stimulus is applied and can be described as _____, _____, _____, _____ pain
vs.
Slow pain: felt _____ and then increases _____ over time and is associated with _____ _____. Can be described as _____ _____, _____, _____, _____ pain and _____ pain
Pain:
Anterolateral pathway
Fast pain: is felt within 0.1 second after a pain stimulus is applied
Sharp, pricking, acute, electric pain
vs.
Slow pain: felt after 1 second or more and then increases slowly over time and is associated with tissue destruction. Can be described as slow slow burning, aching, throbbing, nauseous pain and chronic pain
Nociceptors (pain receptors):
Part of which pathway?
_____ nerve endings
Widespread in the _____ layers of the skin
Widespread in _____ tissues
_____ tissues are sparsely supplied
_____ adapting
Nociceptor (pain receptors):
Anterolateral pathway
Free nerve endings
Widespread in the superficial layers of the skin
Widespread in internal tissues
Deep tissues are sparsely supplied
Non-adapting! As long as there is stimulus they will let you know there is pain!
Stimulus of Nociceptor (pain receptors):
Name 3 ways Nociceptors are stimulated
Stimulus of Nociceptor (pain receptors):
Mechanical, Thermal, Chemical
Mechanical and Thermal are more specific* to fast pain
Chemical is more specific* to slow pain
*(all 3 can can be either)
Fast pain: (*know fiber, velocity, and NT!*)
Signals are transmitted by fast fibers (_____ fibers)
Velocity between ___ and ___ m/sec
Enter the _____ tract
Can be _____ when _____ receptors and _____ receptors are simultaneously stimulated
_____ as main NT
Fast pain: (*know fiber, velocity, and NT!*)
Signals are transmitted by fast fibers (Aδ fibers)
Velocity between 6 and 30 m/sec
Enter the neospinothalamic tract
Can be localized** when **pain receptors and tactile receptors are simultaneously stimulated
Glutamate as main NT
Slow-chronic pain: (*know fiber, velocity, and NT!*)
Signals are transmitted by _____ _____ fibers
Velocity between ___ and ___ m/sec
Enter the _____ pathway
_____ localization
Neurotransmiters; _____ as main NT
Slow-chronic pain: (*know fiber, velocity, and NT!*)
Signals are transmitted by type C fibers
Velocity between 0.5 and 2 m/sec
Enter the paleospinothalamic pathway
Poor localization
Glutamate and Substance P; Substance P as main NT
Fast pain vs. Slow pain key points:
Fast pain uses _____ fibers, has a _____ velocity (___-___ m/sec), enters the _____ tract, _____ _____ localized, and uses _____ as the main neurotransmitter.
vs.
Slow pain uses _____ fibers, has a _____ velocity (___-___ m/sec), enters the _____ pathway, _____ _____ localized, and uses _____ as the main neurotransmitter.
Fast pain vs. Slow pain key points:
Fast pain uses fast Aδ fibers, has a faster velocity (6-30 m/sec), enters the neospinothalamic tract, can be localized, and uses glutamate as the main neurotransmitter.
vs.
Slow pain uses type C fibers, has a slower velocity (0.5-2 m/sec), enters the paleospinothalamic pathway, is poorly localized, and uses Substance P as the main neurotransmitter.
Pain:
Double pain sensation: First a fast-_____ pain followed by a slow pain
***Think; What is main NT for the first fast pain? the second slow pain?***
Referred pain: Usually through _____spinothalamic pathway
Pain:
Double pain sensation: First a fast-sharp pain followed by a slow pain
***Glutamate is the main NT for the first fast pain! Substance P for the second slow pain!***
Referred pain: Usually through paleospinothalamic pathway
Pain Modification:
2 ways to modify pain?
Pain Modification:
1) Massage or rubbing;
Massaging and rubbing activates mechanoreceptors.
Pain evoked by the nociceptors (A δ and C fibers) can be reduced by simultaneous activity of the mechanoreceptors
2) endorphins
Inhibit nociceptors*!
*(inhibits the pre-synaptic release of Sub P.)
Clinical Case example:
An individual was brought into the ED following a motor vehicle collision. This individual is conscious and reports no loss of consciousness during the accident. There is no physical evidence of any head trauma. However, upon examination of this individual, the following sensory deficits are noted: loss of fine touch and vibration sense in both the left arm and leg including the hand and foot, loss of pain and temperature sense in the right arm and leg including the hand and foot.
Clinical Case example:
Use this case as an example to think about the nerve tracts used, area of the somatosensory cortex used, pain localization principles, main neurotransmitters respoible for the pain recepters, and location of the tactile receptors learned in this lecture.
The loss of fine touch and vibration sense involves which of the following nerve tracts?
A. Anterolateral system
B. Dorsal-column system
C. Corticospinal tract
D. Medial forebrain bundle
The loss of fine touch and vibration sense involves which of the following nerve tracts?
B.
Dorsal-column system
The loss of pain and temperature sense involves which of the following nerve tracts?
A. Corticospinal tract
B. Pontocerebellar tract
C. Dorsal-column tract
D. Anterolateral system
The loss of pain and temperature sense involves which of the following nerve tracts?
D.
Anterolateral system
Which of the following areas of the body has the greatest representation in the primary somatosensory cortex?
A. Tongue
B. Head
C. Shoulder
D. Wrist
Which of the following areas of the body has the greatest representation in the primary somatosensory cortex?
A.
Tongue
The highest degree of pain localization comes from?
A. Simultaneous stimulation of free nerve endings and tactile fibers
B. Stimulation of free nerve endings by bradykinin
C. Nerve fibers traveling via the paleospinothalamic system
D. Stimulation of the A δ fibers
The highest degree of pain localization comes from?
A.
Simultaneous stimulation of free nerve endings and tactile fibers
*localized when pain receptors and tactile receptors are simultaneously stimulated; Stimulation of the A δ fibers is what causes the pain and localization signal to travel quickly, but it is not where pain localization “comes from”
Which substance is responsible for activating pain receptors?
A. Bradykinin
B. Glutamate
C. Substance P
D. Endorphines
Which substance is responsible for activating pain receptors?
A.
Bradykinin
*B & C are NT! D inhibits the pre-synaptic release of Sub P.
Second pain is initiated by?
A. C fibers and is a sharp, highly localized sensation
B. C fibers and is a dull, poorly localized sensation
C. Aδ fibers and is a sharp, highly localized sensation
D. Aδ fibers and is a dull, poorly localized sensation
Second pain is initiated by?
B.
C fibers and is a dull, poorly localized sensation
Pacinian corpuscles are located?
A. Superficially in the dermis and detect rapid changes
B. Deep in the dermis and detect rapid changes
C. Superficially in the dermis and detect slow changes
D. Deep in the dermis and detect slow changes
Pacinian corpuscles are located?
B.
Deep in the dermis and detect rapid changes
