Sensory Functions and Hearing Overview
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Questions and Answers

What is the primary function of the middle ear?

  • Match low-impedance airborne sounds to higher-impedance fluid sounds (correct)
  • Convert sound waves into neural impulses
  • Amplify sound waves to improve their quality
  • Transmit sound waves directly to the auditory cortex

How does the middle ear protect the inner ear from loud sounds?

  • By amplifying sound waves before they reach the cochlea
  • By increasing the stiffness of the ossicles during loud noises
  • By dampening low-frequency sounds before they enter the inner ear
  • By using the tensor tympani and stapedius muscles to attenuate sound energy (correct)

In which part of the ear do sound waves get converted into neural impulses?

  • Middle ear
  • Auditory meatus
  • Outer ear
  • Cochlea of the inner ear (correct)

What range of sound frequencies can humans generally detect?

<p>20 Hz to 20000 Hz (C)</p> Signup and view all the answers

What mechanism does the middle ear utilize to amplify sound vibrations?

<p>Lever action of the ossicles (A)</p> Signup and view all the answers

What happens to sound waves at the tympanic membrane?

<p>They create vibrations that are sent to the middle ear (C)</p> Signup and view all the answers

Which of the following is a function of the cochlea?

<p>Analyzing and transforming sound energy into neural activity (A)</p> Signup and view all the answers

What would happen if sound exceeded 150 dB?

<p>It could lead to eardrum rupture (B)</p> Signup and view all the answers

What is the function of the cochlear partition in the cochlea?

<p>It supports the movement of the basilar membrane. (C)</p> Signup and view all the answers

What determines the point of maximum displacement in the cochlea's basilar membrane?

<p>The frequency of the stimulus. (B)</p> Signup and view all the answers

Which type of wave propagates from the base to the apex of the cochlear structure?

<p>Traveling wave. (A)</p> Signup and view all the answers

What is the role of stereocilia in hair cells?

<p>They initiate sensory transduction by bending and causing voltage changes. (A)</p> Signup and view all the answers

How many rows of outer hair cells are present in the cochlea of humans?

<p>Three rows. (B)</p> Signup and view all the answers

What role do otoconia play in the functioning of the otolithic membrane?

<p>They enhance the sensitivity of the otolithic membrane to gravity and linear motion. (B)</p> Signup and view all the answers

What is the relationship between the basilar membrane and the tectorial membrane during the traveling wave?

<p>They are anchored at different positions, creating a shearing motion. (A)</p> Signup and view all the answers

What type of axons terminate on the outer hair cells in the cochlea?

<p>Efferent axons from the superior olivary complex. (B)</p> Signup and view all the answers

What happens to vestibular hair cells when stereocilia are bent towards the kinocilium?

<p>They become depolarized and excited. (C)</p> Signup and view all the answers

Which structure in the vestibular system is responsible for detecting angular acceleration?

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

Which structure connects the scala vestibuli to the scala tympani?

<p>Helicotrema. (C)</p> Signup and view all the answers

How do the utricle and saccule contribute to balance?

<p>By sensing linear acceleration and head position in relation to gravity. (D)</p> Signup and view all the answers

What is the primary function of the ampulla found in the semicircular canals?

<p>To house sensory hair cells. (B)</p> Signup and view all the answers

What ionic difference is critical for the mechanoelectrical transduction in vestibular hair cells?

<p>High potassium (K+) concentration in endolymph. (C)</p> Signup and view all the answers

What effect does bending of stereocilia away from the kinocilium have on hair cells?

<p>It causes hyperpolarization. (C)</p> Signup and view all the answers

What happens to hair cells when they are deflected toward the kinocilium?

<p>Depolarization occurs and neurotransmitter release increases. (B)</p> Signup and view all the answers

Which component of the vestibular system helps synchronize movements with balance and spatial orientation?

<p>Neural pathways (C)</p> Signup and view all the answers

What role does the endolymph flow play during head rotation?

<p>It flows opposite to head rotation to displace the cupula. (D)</p> Signup and view all the answers

Which sensory system is responsible for registering information from inside the body?

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

How is signal integration for balance achieved in the sensory systems?

<p>By combining vestibular input with visual and somatosensory information. (D)</p> Signup and view all the answers

What does Weber’s Law indicate about the perception of changes in stimuli?

<p>The increment threshold to background intensity remains constant. (A)</p> Signup and view all the answers

Which part of the vestibular apparatus ensures stabilization of gaze during head movements?

<p>Vestibulo-Ocular Reflex (VOR) (C)</p> Signup and view all the answers

What characteristic of hair cell activation correlates with head movement?

<p>The speed and direction of head movement. (B)</p> Signup and view all the answers

What is the purpose of the signals sent by hair cells to the vestibular nerve?

<p>To inform the brainstem's vestibular nuclei for balance control. (D)</p> Signup and view all the answers

What type of mechanoreceptors are primarily responsible for detecting touch and texture perception?

<p>Merkel receptors (C)</p> Signup and view all the answers

Which pathway is responsible for relaying sound signals?

<p>Medial geniculate nucleus pathway (C)</p> Signup and view all the answers

Which mechanosensitive ion channel is primarily found in non-neuronal tissues?

<p>Piezo1 (C)</p> Signup and view all the answers

What is the role of the Golgi tendon organ in proprioception?

<p>Detects muscle force (B)</p> Signup and view all the answers

How is accurate two-point discrimination achieved?

<p>Through the activation of distinct receptive fields and lateral inhibition (D)</p> Signup and view all the answers

Which of the following best describes the function of the Dorsal column-medial lemniscus pathway?

<p>Transmits signals related to fine touch and vibration (A)</p> Signup and view all the answers

What influences the processing of sensory input based on alertness?

<p>Sleep-Wake Cycles (A)</p> Signup and view all the answers

Which receptor type is primarily responsible for detecting distant events through transmitted vibration?

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

What role does interphotoreceptor retinoid-binding protein (IRBP) play in the transport of visual pigments?

<p>It transports all-trans-retinol to the retinal pigment epithelium (RPE). (B)</p> Signup and view all the answers

What happens to 11-cis-retinal in the photoreceptor cells?

<p>It binds to opsin to form rhodopsin. (C)</p> Signup and view all the answers

Why do cones synapse to one bipolar cell while many rods synapse to one bipolar cell?

<p>Cones are specialized for spatial resolution. (C)</p> Signup and view all the answers

How do on-center and off-center ganglion cells respond to light?

<p>On-center cells are excited by light in the center, off-center cells are excited by light in the surround. (A)</p> Signup and view all the answers

What is the primary function of the receptive field in ganglion cells?

<p>To process light stimuli that influence ganglion cell activity. (A)</p> Signup and view all the answers

What characterizes the central processing of visual input from ganglion cells?

<p>It processes information in both eyes and combines signals. (D)</p> Signup and view all the answers

What is the significance of ocular dominance in visual processing?

<p>It ensures equal processing of visual stimuli from both eyes. (D)</p> Signup and view all the answers

What process initiates the differentiation of objects against their background?

<p>The identification of edges in the visual field. (C)</p> Signup and view all the answers

Flashcards

Sound

The movement of sound waves through the air, characterized by frequency (pitch) and amplitude (loudness).

Pitch

The perceived highness or lowness of a sound, determined by the frequency of sound waves.

Loudness

The perceived intensity of a sound, determined by the amplitude of sound waves.

Outer ear

The outer part of the ear, responsible for collecting and directing sound waves towards the middle ear.

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Middle ear

The air-filled cavity located within the temporal bone, which contains the three ossicles.

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Ossicles

The three tiny bones (malleus, incus, and stapes) in the middle ear that transmit vibrations from the eardrum to the inner ear.

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Inner ear

The innermost part of the ear, containing the cochlea, responsible for converting sound waves into electrical signals.

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Cochlea

The fluid-filled, spiral-shaped structure in the inner ear responsible for transforming sound waves into neural impulses.

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What is the vestibular system?

The vestibular system is a part of the inner ear that helps maintain balance, posture, and spatial orientation by detecting changes in motion and head position.

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What are semicircular canals?

The semicircular canals are three fluid-filled tubes in the inner ear that detect rotational movements.

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What is the ampulla?

The ampulla is a bulge at the end of each semicircular canal that houses sensory hair cells embedded in a gelatinous structure called the cupula.

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What are the otolith organs?

The otolith organs, the utricle and saccule, detect linear acceleration and head position relative to gravity.

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What are otoconia?

Otoconia are tiny calcium carbonate crystals that weigh down the otolithic membrane, increasing its sensitivity to gravity and linear motion.

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Cochlear partition

A flexible structure within the cochlea that supports the basilar membrane and the tectorial membrane.

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Scala vestibuli

The fluid-filled chamber located above the cochlear partition.

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What are vestibular hair cells?

Vestibular hair cells are found in the semicircular canals and otolith organs, and they detect changes in motion.

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Scala tympani

The fluid-filled chamber located below the cochlear partition.

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What is endolymph?

Endolymph is a fluid located in the semicircular canals and otolith organs and surrounds the hair cells. It helps to transmit movement signals.

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Scala media

A channel within the cochlear partition, filled with a different fluid than the scala vestibuli and tympani.

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What is perilymph?

Perilymph is a fluid located in the inner ear that surrounds the base of the hair cells. It plays a role in maintaining the stability of the inner ear.

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Point of maximum displacement

The point on the basilar membrane where the traveling wave reaches its maximum displacement, determined by the frequency of the sound.

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Sensory hair cells

The sensory hair cells located on the basilar membrane that are responsible for converting mechanical vibrations into electrical signals.

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Stereocilia

The hair-like processes that protrude from hair cells and bend in response to the shearing motion between the basilar and tectorial membranes.

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Hair cell receptor potential

The bending of stereocilia in the hair cells leads to voltage changes across the cell membrane, triggering a signal.

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DCML Pathway

Signals related to fine touch and vibration are transmitted through the dorsal column-medial lemniscus pathway (DCML). This pathway carries information from both the lower and upper body, allowing for precise sensory perception.

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Two-Point Discrimination

The two-point discrimination threshold is the smallest distance between two points that can be perceived as separate. It varies across the body, being smaller in areas with higher sensory density.

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Mechanoreceptors

Mechanoreceptors are specialized sensory neurons that convert mechanical stimuli into electrical signals. They play a crucial role in touch, pressure, and proprioception.

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Piezo Channels

Piezo channels are mechanosensitive ion channels that are essential for converting mechanical stimuli into electrical signals in the nervous system.

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Proprioception

Proprioception is the sense of our body's position and movement in space. It involves specialized receptors within muscles and joints that provide information about muscle length, tension, and joint angle.

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Golgi Tendon Organ

The Golgi tendon organ is a sensory receptor located in the tendons that detects muscle force. It plays a role in fine-tuning muscle contraction and protective reflexes.

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Cerebellum Role

The cerebellum is a brain structure that plays a vital role in coordinating movement, balance, and motor learning. It receives proprioceptive input allowing it to fine-tune muscle activity.

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Divergent Neural Connections

A single neuron can transmit its signal to multiple locations, allowing for the integration of information from different parts of the nervous system.

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Interphotoreceptor Retinoid-Binding Protein (IRBP)

A protein that transports all-trans-retinol from photoreceptors to the RPE and back.

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Rhodopsin

The pigment in photoreceptor cells that absorbs light and initiates the visual process.

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Visual Cycle

The conversion of all-trans-retinol to 11-cis-retinal, which is necessary for rhodopsin to function.

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Photopsin

The pigment that absorbs light in cones, responsible for color vision.

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Bipolar Cells

Specialized cells in the retina that receive input from photoreceptor cells (rods and cones).

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Receptive Field

The area of the retina where light stimuli influence a ganglion cell's activity.

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On-center Ganglion Cell

A type of ganglion cell excited by light in the center of its receptive field and inhibited by light in the surrounding area.

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Off-center Ganglion Cell

A type of ganglion cell inhibited by light in the center of its receptive field and excited by light in the surrounding area.

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How does head rotation activate the vestibular system?

When the head rotates, the endolymph inside the semicircular canals lags behind due to its viscosity, displacing the cupula and bending the hair cells.

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How do hair cell deflections affect neural signals?

Deflection of hair cells towards the kinocilium causes depolarization, increasing neurotransmitter release and firing rate of the vestibular nerve. Deflection away from the kinocilium causes hyperpolarization, reducing neurotransmitter release.

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What is the relationship between endolymph flow and head movements?

The flow of endolymph is opposite to the direction of head rotation, creating the force to displace the cupula. The extent of hair cell activation reflects the speed and direction of head movement.

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How is information from the vestibular system processed?

The vestibular nerve carries signals from hair cells to the vestibular nuclei in the brainstem, where they are integrated with visual and somatosensory inputs for a cohesive sense of balance.

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What is the vestibulo-ocular reflex (VOR) and its function?

The vestibulo-ocular reflex (VOR) generates compensatory eye movements in the opposite direction of head rotation, stabilizing gaze during head movements.

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What are exteroception, interoception, and proprioception?

Exteroception: information from outside the body (e.g., touch, sight). Interoception: information from inside the body (e.g., hunger, pain). Proprioception: information about self (e.g., body position).

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What is the role of the stimulus threshold in sensory perception?

Only sensory signals that surpass a stimulus threshold are transmitted to the brain, filtering out unimportant details.

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What is Weber's Law and how does it relate to sensory perception?

Weber's Law states that the ratio of the increment threshold to the background intensity is constant. The equation is P = Kia (where P is perceived intensity, K is a constant, I is background intensity, and a is the exponent).

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Study Notes

Sensory Functions

  • Describe different types of specialized sensory cells/receptors for various sensory modalities (touch, proprioception, pain, vision, hearing, balance/spatial orientation, taste, and smell). Includes anatomical and histological organization.
  • Explain how sensory cells/receptors transduce stimuli into electrical signals for different sensory modalities.
  • Define the central pathways that convey sensory information from different body parts.
  • Explain how sensory information is processed in specific brain regions for different sensory modalities.
  • Explain how different sensory stimuli are perceived and how they can be modulated.

Hearing

  • Sound is characterized by frequency (pitch) and amplitude (loudness, measured in decibels).
  • A 150 dB sound can rupture the eardrum.
  • The audible frequency range is 20 Hz to 20,000 Hz.
  • Outer ear directs sound (consists of the pinna, concha, and auditory meatus).
  • Middle ear transmits vibrations from the tympanic membrane to the inner ear (cavity filled with air in the temporal bone, matching relatively low impedance airborne sounds to the higher impedance of the inner ear fluid through: amplification mechanism & attenuation mechanism).
  • Inner ear: comprises hearing and vestibular functions (cochlea, auditory nerve, oval window, round window, vestibular nerve).

Inner Ear (cont.)

  • The inner ear contains a membrane labyrinth including endolymphatic duct, ampullae, Scarpa's ganglion, semicircular canals, superior, posterior and horizontal, and vestibular part of cranial nerve VIII (facial and auditory).
  • The cochlea converts sound energy into neural impulses; this organ comprises the scala vestibuli, scala media, scala tympani, Reissner's membrane, the organ of Corti, and the basilar membrane.
  • The traveling wave in the cochlea results in the displacement of the basilar membrane, determining the stimulated frequencies. High frequencies are processed at the base of the membrane, while low frequencies are processed at the apex.
  • Hair cells convert the mechanical vibrations into electrical signals. Bending of stereocilia towards the kinocilium causes depolarization, and bending away causes hyperpolarization. (this leads to adaptation in vestibular hairs and allows for continued signaling despite large forces of gravity).
  • Endolymph is high in potassium, and perilymph is similar to extracellular fluid.
  • The vestibular system detects head movements, enabling balance, posture, spatial orientation, and coordination of eye movements.

Vestibular System

  • Hair cells in the semicircular canals, utricle, and saccule convert rotational/rotational movements into neural signals.
  • The semicircular canals detect angular acceleration and vestibular hair cells in utricle and saccule detect linear acceleration/head position relative to gravity.
  • Otoconia (calcium carbonate crystals) in the otolithic membrane enhance the system's sensitivity to gravity and linear motion.
  • Displacement of otoconia bends stereocilia on hair cells, initiating neural signals, and the flow of endolymph is opposite to the direction of head rotation.
  • This system integrates information from multiple sensory systems (visual and proprioceptive) for balance and spatial awareness.
  • Vestibular pathway transmits sensory information to the brainstem (vestibular nuclei), cranial nerve nuclei (e.g., VOR), spinal cord, and cortex; influencing posture, balance, and spatial awareness.

Sensory Systems

  • Classify sensory information into exteroception (external), interoception (internal), and proprioception (self).
  • Specialized receptors with specific thresholds filter irrelevant sensory information for the brain.
  • Sensory modalities include mechanoreception, chemoreception, photoreception, and thermoreception.
  • The brain interprets the signals from these systems, considering factors including intensity, location, quality, and duration.

Vision

  • Discuss hyperalgesia (increased pain) and allodynia (pain evoked by non-painful stimuli) and analgesic drugs.

Anatomy

  • Describe the anatomy of the eye and ear, including muscles, structures, and layers.

Other (Sensory Processes)

  • Explain how signals are processed in the central nervous system (eg, thalamus, cortex) for all senses, including the types of pathways and connections.
  • Sensory receptor types; explain how they convert stimuli into electrical signals.

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Description

This quiz covers the various specialized sensory receptors for modalities such as touch, hearing, and vision. It explores how these receptors transduce stimuli into electrical signals and how sensory information is processed in the brain. Test your knowledge on sound characteristics, ear anatomy, and more!

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