Videoaula 8 Sistema auditivo e vestibular - AUDIÇÃO E EQUILÍBRIO

Summary

This video script explores the complex sensory systems of the human body, focusing on the auditory and vestibular systems. It delves into the anatomy of the ear, explaining how sound is perceived, starting from the outer ear to the cochlea, where sensory receptors, called hair cells, convert sound vibrations into electrical signals. The script also covers the vestibular system's role in maintaining balance and spatial orientation through the detection of head movements and position. It highlights the interconnectivity of these systems in processing auditory and spatial information, and how the brain integrates these signals for balance and perception.

Takeaways

• 😀 The human ear is divided into three parts: the outer ear (auricle and auditory canal), middle ear (three small bones: hammer, anvil, stirrup), and inner ear (vestibular apparatus and cochlea).
• 😀 The auditory system's sensory transduction involves the detection of sound waves, which are mechanical vibrations propagated through air, water, or solids.
• 😀 Sound waves can be described by their frequency (measured in Hertz) and amplitude (measured in decibels), which influence the pitch and volume of the sound.
• 😀 In the cochlea, sound waves cause vibrations that lead to the depolarization of hair cells, which then send electrical signals to the brain via the auditory nerve.
• 😀 Potassium influx is key to the depolarization of hair cells in the cochlea, as the endolymph in the cochlear duct has high potassium concentrations.
• 😀 The auditory pathway includes the cochlear nerve, brainstem cochlear nuclei, superior olive, midbrain, thalamus, and ultimately the primary auditory cortex.
• 😀 The cochlea is tonotopically organized, meaning different parts respond to different frequencies, and this organization is reflected in the auditory cortex.
• 😀 The vestibular system detects head position and movement, and plays a crucial role in maintaining balance by activating specific muscles in response to changes in head orientation.
• 😀 The vestibular apparatus contains structures like the sac and utricle, which use hair cells to detect the effects of gravity and movement on the body.
• 😀 The semicircular canals in the vestibular system detect head movements and use fluid inertia to trigger sensory responses that maintain balance and eye stabilization.
• 😀 Information from the vestibular system can be processed in areas like the cerebellum and thalamus to adjust body posture and balance in response to movement or changes in orientation.

Q & A

What is the basic structure of the human ear?

The human ear is divided into three parts: the outer ear (auricle or pinna), the middle ear (containing the hammer, anvil, and stirrup bones), and the inner ear (comprising the vestibular apparatus and cochlea).

How does sound travel through the auditory system?

Sound waves captured by the outer ear vibrate the tympanic membrane. These vibrations are transmitted through the middle ear bones, amplified by the stapes, and then transferred to the fluid in the cochlea. This causes the basilar membrane to vibrate, stimulating hair cells that convert the mechanical vibrations into electrical signals.

What is the role of hair cells in the auditory system?

Hair cells in the cochlea act as sensory receptors. They detect vibrations and have stereocilia that, when deformed, open mechanical channels to allow potassium ions to enter the cells, leading to depolarization and the generation of action potentials.

What causes depolarization in hair cells in the cochlea?

Depolarization occurs when the stereocilia of hair cells are deformed by vibrations, causing mechanical channels to open and allowing potassium ions to enter the cells. The high potassium concentration in the endolymph contributes to this effect.

How do sound wave frequencies correlate with the perception of pitch?

Higher frequency sound waves, with shorter wavelengths, are perceived as higher-pitched sounds. Lower frequency waves, with longer wavelengths, are perceived as lower-pitched sounds. The cochlea's tonotopic map processes these frequencies based on their location within the cochlea.

How does the auditory system localize sound?

Sound localization is achieved by comparing the time it takes for a sound to reach each ear. If the sound reaches the left ear later than the right ear, the brain processes this difference to determine the direction of the sound source.

What is the role of the vestibular system?

The vestibular system detects the position and movement of the head, which is crucial for maintaining balance. It uses sensory receptors located in the vestibular apparatus, including the sac and utricle, to detect changes in head orientation and movement.

Why is the vestibular system important for balance?

The vestibular system helps maintain balance by detecting head position and movement. It activates specific muscles in response to changes in head orientation, preventing falls by adjusting body posture accordingly.

How does the vestibular system detect head movement?

The semicircular canals in the vestibular system detect head movement. The canals contain a gelatinous substance with embedded crystals called otoliths. When the head moves, the otoliths shift, causing the deformation of hair cells, which generates electrical signals that send information to the brain.

What happens when a person spins and then stops?

When a person spins and then stops, the fluid in the semicircular canals continues to move due to inertia, causing a sensation of movement. This conflicting information leads to dizziness and balance disturbances as the body tries to adjust.