Somatosensation
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Questions and Answers

What type of tactile receptor is known for responding best to indentation?

  • SA1 - Merkel cells (correct)
  • SA 2
  • FA 2 - Pacinian corpuscles
  • FA 1 - Meissner corpuscles

Which receptor would be best suited for perceiving fine textures through transmitted vibration?

  • SA 2 receptors
  • FA1 - Meissner corpuscles
  • SA1 - Merkel cells
  • FA2 - Pacinian corpuscles (correct)

Which of the following statements about spatial resolution is correct?

  • Spatial resolution is irrelevant to tactile sensations.
  • Higher thresholds equate to better spatial awareness.
  • The thigh has a high resolution due to a low threshold.
  • Fingers can discriminate two points due to high receptor density. (correct)

What type of mechanoreceptor is identified as responding predominantly to skin stretch?

<p>SA 2 receptors (D)</p> Signup and view all the answers

How do slowly adapting (SA) tactile receptors differ from rapidly adapting (FA) receptors?

<p>SA receptors maintain response for the duration of the stimulus. (A)</p> Signup and view all the answers

Which tactile receptor is primarily responsible for maintaining grip control?

<p>FA1 - Meissner corpuscles (B)</p> Signup and view all the answers

Pacinian corpuscles have a small receptive field and are sensitive to pressure.

<p>False (B)</p> Signup and view all the answers

What is the role of Merkel cells in somatosensation?

<p>They respond best to indentation and help perceive pattern, texture, and shape.</p> Signup and view all the answers

The ______ sensation provides information about the external environment through tactile receptors located in the skin.

<p>touch</p> Signup and view all the answers

Match the following tactile receptors with their primary characteristic:

<p>Merkel cells = Respond best to indentation Meissner corpuscles = High sensitivity to temporal variations Pacinian corpuscles = Respond best to vibration SA 2 receptors = Low sensitivity to temporal variations</p> Signup and view all the answers

What is the primary function of proprioceptors in the body?

<p>To signal dynamic changes in muscle length (A), To maintain the optimal operating length of muscle spindles (B)</p> Signup and view all the answers

Which statement best describes a characteristic of joint receptors?

<p>They are primarily activated at the limits of joint motion. (D)</p> Signup and view all the answers

Which type of neuron innervates Golgi tendon organs?

<p>Type 1b afferent neurons (D)</p> Signup and view all the answers

What does the term 'touch physiology' primarily refer to?

<p>The journey of tactile information from skin to brain (A)</p> Signup and view all the answers

What role does tactile spatial attention play in sensory processing?

<p>It influences the expectation and processing of touch-related information. (B)</p> Signup and view all the answers

What is the primary function of nociceptors in the skin?

<p>To detect acute pain and harmful stimuli (D)</p> Signup and view all the answers

What type of fibers are classified as C-fibers?

<p>Narrow, unmyelinated fibers that transmit pain slowly (B)</p> Signup and view all the answers

Which receptor is activated by menthol, providing a cold sensation?

<p>Trpm8 (B)</p> Signup and view all the answers

What role does proprioception play in the sensory system?

<p>It provides information about body parts' positions and movements (A)</p> Signup and view all the answers

Which sensation is described as resulting from an inflammatory response that makes a site of damage more sensitive?

<p>Hyperalgesia (D)</p> Signup and view all the answers

What condition was suffered by 'Miss C', who was born with insensitivity to pain?

<p>Inability to react with reflexes such as sneezing or blinking (C)</p> Signup and view all the answers

What is kinaesthesia often used interchangeably with?

<p>Proprioception (B)</p> Signup and view all the answers

What aspect of haptic perception involves knowing the location of objects using touch?

<p>The 'Where' system (D)</p> Signup and view all the answers

What is the primary function of proprioceptors?

<p>Provide information about the position and movement of the body (B)</p> Signup and view all the answers

Egocenter refers to the center of a reference frame that is not relative to the body's position.

<p>False (B)</p> Signup and view all the answers

What is the primary role of the Golgi tendon organs?

<p>To sense tension (force) in the muscle fibers.</p> Signup and view all the answers

The __________ experience demonstrates how touch can change one's body image perception.

<p>rubber-hand</p> Signup and view all the answers

Match the following proprioceptors with their primary functions:

<p>Muscle spindles = Signal changes in muscle length Golgi tendon organs = Sense tension in muscle fibers Joint receptors = Signal limits of joint motion Fusimotor system = Maintain optimal spindle length</p> Signup and view all the answers

Which type of fibers is responsible for sensing acute pain in response to harmful stimuli?

<p>C-fibers (B), A-delta fibers (D)</p> Signup and view all the answers

Proprioception refers to the body's ability to detect changes in external temperature.

<p>False (B)</p> Signup and view all the answers

What type of pain results from damage to the nervous system?

<p>Neuropathic pain</p> Signup and view all the answers

The sensation of cold can be activated by the chemical __________.

<p>menthol</p> Signup and view all the answers

Match the type of receptor with its corresponding sensation:

<p>C-fibers = Slow pain sensation A-delta fibers = Fast pain sensation Trpm8 = Cold sensation Trpv1 = Warm sensation</p> Signup and view all the answers

What is the main function of thermoreceptors in the skin?

<p>Sense temperature changes (C)</p> Signup and view all the answers

Individuals with insensitivity to pain do not experience injury.

<p>False (B)</p> Signup and view all the answers

What is the primary system that plays a role in the perception of movement of our limbs?

<p>Kinaesthesia</p> Signup and view all the answers

Which pathway carries signals from pain and thermoreceptors?

<p>Spinothalamic pathway (A)</p> Signup and view all the answers

The primary somatosensory cortex is located in the frontal lobe.

<p>False (B)</p> Signup and view all the answers

What is the role of the dorsal root ganglion?

<p>Contains the cell body of primary afferent neurons.</p> Signup and view all the answers

The somatosensory map in the primary somatosensory cortex is not proportional to the ________ of the skin innervated.

<p>area</p> Signup and view all the answers

Match the following components with their respective functions:

<p>Thalamus = Relays sensory information to the cortex Primary Somatosensory Cortex = Processes tactile sensory input Dorsal Column = Carries signals from tactile receptors Ventral Pathway = Involved in integrating sensory information with memory</p> Signup and view all the answers

The spinothalamic pathway is primarily responsible for transmitting information about fine touch and vibration.

<p>False (B)</p> Signup and view all the answers

What type of sensory receptors are located at the interface between the extrafusal muscle fibers and the tendon?

<p>Golgi tendon organs</p> Signup and view all the answers

The ______ system is responsible for maintaining the optimal length of muscle spindles during muscle contraction.

<p>fusimotor</p> Signup and view all the answers

Match the following types of receptors with their respective functions:

<p>Muscle spindles = Sense muscle length changes Type 1b afferent neurons = Innervate Golgi tendon organs Joint receptors = Signal limits of joint motion SA1 receptors = Provide information on braille encoding</p> Signup and view all the answers

Which pathway is involved in carrying information about pain, temperature, and crude touch?

<p>Spinothalamic Pathway (C)</p> Signup and view all the answers

Tactile agnosia refers to the difficulty in identifying objects through vision.

<p>False (B)</p> Signup and view all the answers

What term is used to describe the representation of the body in relation to the area of skin and the cortex that represents it?

<p>Homonculus</p> Signup and view all the answers

Flashcards

Tactile Receptors

Specialized nerve endings in the skin that detect mechanical stimuli like pressure and vibration.

Merkel Cells

Tactile receptors that respond to indentation and provide high spatial resolution for perceiving details like texture and shape.

SA 2 Receptors

Tactile receptors that respond to skin stretch and provide information about the overall shape and position of the hand.

Meissner Corpuscles

Tactile receptors specialized for detecting changes in skin contact, important for grip control and motion detection.

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2-point discrimination

Ability to distinguish two nearby touch stimuli as separate, depending on receptor density/location.

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What does transduction mean in touch?

Transduction in touch refers to the process of converting mechanical energy like pressure or vibration into electrical signals that the brain can understand.

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What are the two main types of adaptation for tactile receptors?

Tactile receptors can adapt either slowly (SA) or fast/rapidly (FA). SA receptors fire continuously as long as the stimulus is present, while FA receptors only fire at the beginning and end of the stimulus.

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What is the difference between spatial and temporal resolution?

Spatial resolution refers to how well you can distinguish between two points of touch, while temporal resolution refers to how well you can distinguish between two events in time.

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What do Pacinian Corpuscles do?

Pacinian corpuscles are fast-adapting (FA) receptors with a large receptive field. They are highly sensitive to vibration and help us perceive fine textures through transmitted vibrations.

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What is the relationship between receptor density and 2-point discrimination?

The higher the density of receptors in an area of skin, the better the 2-point discrimination, meaning you can distinguish between two nearby points of touch more easily.

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Frame of Reference (Touch)

A coordinate system used to pinpoint locations in space relative to your body, like a personal map for touch.

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Egocenter

The central point of a touch reference frame, usually located at the center of your body. It's like a touchy 'you' at the heart of your touch map.

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Body Image

How your brain perceives and understands the shape, size, and position of your body in space. It's not just about seeing yourself, but feeling your body.

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Rubber-Hand Illusion

A fascinating phenomenon showing how easily our body image can be tricked. It's like our brain can be convinced a fake hand is really ours, by combining touch and sight.

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Tactile Spatial Attention

Our ability to focus our touch attention on specific areas of our body, like a spotlight shining on a particular area of our skin.

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Thermoreceptors

Specialized nerve endings in the skin that detect temperature changes. They respond to different temperature ranges, with warm fibers firing more at higher temperatures and cold fibers firing more at lower temperatures.

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What are the two main types of sensory fibers for pain?

Pain signals are carried by two types of fibers: A-delta fibers, which are faster and myelinated, and C-fibers, which are slower and unmyelinated. A-delta fibers transmit sharp, initial pain, while C-fibers transmit throbbing, long-lasting pain.

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What is hyperalgesia?

Increased sensitivity to pain at the site of an injury, often caused by inflammation.

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What is neuropathic pain?

Pain caused by damage to or dysfunction of the nervous system. This pain can be chronic and difficult to treat.

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What is proprioception?

The sense of body position and movement. It allows us to know where our limbs are in space without looking at them.

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What is the difference between interoception and proprioception?

Interoception is the awareness of our internal bodily states (e.g., hunger, thirst, heart rate), while proprioception is the awareness of our body position and movement.

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What is haptics?

The sense of touch, specifically the ability to perceive objects in the environment using touch.

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What is Kinaesthesia?

The sense of movement of the limbs, often used interchangeably with proprioception.

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Warm fibers

Thermoreceptors that increase firing rate as skin temperature rises, signaling a feeling of warmth.

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Cold fibers

Thermoreceptors that increase firing rate as skin temperature drops, signaling a feeling of coldness.

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Nociception

The sense of pain, signaling potential harm to the body.

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C-fibers

Unmyelinated nerve fibers that transmit slow, throbbing pain signals from nociceptors in the skin.

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A-delta fibers

Lightly myelinated nerve fibers that transmit fast, sharp pain signals from nociceptors in the skin.

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Proprioception

The sense of body position and where each body part is in relation to others and space.

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Kinaesthesia

The perception of movement of our limbs, often used interchangeably with proprioception.

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What is a frame of reference (touch)?

A coordinate system for locating objects in space relative to your body, like a personal touch map.

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What is egocenter (touch)?

The central point of a touch frame, typically located at the center of your body, like a touchy 'you'.

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What is body image (touch)?

How your brain perceives and understands the shape, size, and position of your body in space.

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What are proprioceptors?

Specialized sensory receptors in muscles, tendons, and joints that provide information about body position and movement.

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How do muscle spindles work?

They sense the length and stretching of muscles, with type 1a fibers signaling dynamic changes and type 2 fibers signaling static length.

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Spinal Cord Structure

The spinal cord has a central gray matter region containing cell bodies and an outer white matter region containing axons. The ventral part controls motor functions, while the dorsal part handles sensory information.

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Dorsal Column-Medial Lemniscal Pathway

This pathway carries signals from tactile receptors and proprioceptors up the spinal cord to the brain. It makes its first synapse in the medulla.

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Spinothalamic Pathway

This pathway carries signals from pain and temperature receptors, synapsing immediately upon entering the spinal cord and then ascending to the brain.

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Somatosensory Cortex Map

The primary somatosensory cortex (S1) is organized topographically, with each section representing a specific area of the body. This representation is not proportional to the skin's area, leading to a distorted 'homunculus' map.

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Dorsal and Ventral Pathways

The dorsal pathway from S1 connects to the posterior parietal cortex and PMC (motor control), while the ventral pathway goes to S2, PFC (higher cognition), and hippocampus (memory).

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Haptic Perception

Knowledge of the world gained through touch receptors in skin, muscles, tendons, and joints. This usually involves actively exploring objects with our hands.

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Perception for Action

Using somatosensation to control our movement, like grasping objects, maintaining posture, and keeping balance. It allows us to interact with the world through touch.

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Exploratory Procedure

A specific hand movement used to touch an object and determine its properties, like smooth, rough, round, etc.

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Haptic Search

Using touch to find a specific characteristic of an object, like finding a raised dot in braille.

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Tactile Agnosia

Inability to recognize objects by touch due to damage to the parietal lobe.

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Muscle Spindles

Sensory receptors in muscles that sense muscle length and changes in length. They help with precise movements and posture.

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Golgi Tendon Organs

Sensory receptors in tendons that sense tension or force in the muscle fibers. They protect muscles from being overloaded.

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Joint Receptors

Sensory receptors in joint capsules that sense the limits of a joint's range of motion. They help protect joints from injury.

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Study Notes

Somatosensation: Body Sensation

  • Somatosensation is the sense of the body. Touch is a component of somatosensation.
  • Touch is the process of converting mechanical energy into signals in the skin. This is called transduction.
  • Exteroception is the sense of the external world.

Tactile Receptors

  • Tactile receptors are located in the skin.
  • Mechanoreceptors are located in the dermis (beneath the epidermis)
  • Tactile receptors are classified based on:
    • Type of stimuli they respond to
    • Size of their receptive field
    • How quickly they adapt (rapidly or slowly).
  • Some receptors fire continuously while the stimulus is present (slow adaptation). Others only fire at the start and end of the stimulus (fast adaptation). Fast adapting receptors are good at detecting changes in touch.
  • Mechanoreceptors respond to pressure, vibration, and movement.

Mechanoreceptor Types

  • Merkel cells (SA 1)

    • Respond best to indentation
    • Small receptive field
    • High spatial resolution (good at discerning fine details), low temporal resolution (not good at detecting rapid changes).
    • Close to the skin surface.
    • Used to perceive pattern, texture, and shape.

  • Ruffini endings (SA 2)

    • Respond best to stretch.
    • Large receptive field
    • Low spatial resolution, low sensitivity to temporal variations.
    • Deeper in the dermis than Merkel cells.
    • Used to perceive skin stretch and hand conformation.

  • Meissner corpuscles (FA 1)

    • Respond best to skin movement.
    • Small receptive field
    • High spatial resolution, medium temporal resolution.
    • Close to the skin surface.
    • Used to perceive slip, and maintain grip control.

  • Pacinian corpuscles (FA 2)

    • Respond best to vibration.
    • Large receptive field
    • Low spatial resolution, high temporal resolution.
    • Deeper in the dermis.
    • Used to perceive fine textures through vibrations.

Spatial and Temporal Resolution

  • Spatial Threshold: The ability to distinguish two separate points of touch.
    • This ability depends on the density of receptors and their location.
    • Fingers have a low threshold (high spatial resolution) and thighs have a high threshold (low spatial resolution).
  • Temporal Resolution: How quickly the system can detect changes in touch.
    • Touch has a relatively fast temporal resolution (5 milliseconds).
    • Vision has a slower temporal resolution (25 milliseconds).

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Description

Explore the fascinating world of somatosensation, focusing on how our body perceives touch through various tactile receptors. Learn about the different types of mechanoreceptors and their functions in detecting changes in our environment. This quiz delves into the intricacies of body sensation and the mechanisms behind our sense of touch.

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