CMSD5280 Audition II - Physiology #1

<p>Walter Bradford Cannon (B)</p> Signup and view all the answers

<p>Regulating the body's internal environment (B)</p> Signup and view all the answers

<p>To prevent mechanical interference with sound detection (C)</p> Signup and view all the answers

<p>1849 (C)</p> Signup and view all the answers

<p>Assisting in the recycling of K+ ions (A)</p> Signup and view all the answers

<p>The blue vessels (B)</p> Signup and view all the answers

<p>Connexin 26 (B)</p> Signup and view all the answers

<p>From hair cells to supporting cells (D)</p> Signup and view all the answers

<p>Disturbance of ionic balance (A)</p> Signup and view all the answers

<p>Supporting cells (A)</p> Signup and view all the answers

<p>Disrupted potassium ion transport (A)</p> Signup and view all the answers

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

<p>Ionic balance maintenance (D)</p> Signup and view all the answers

<p>Disruptions in cochlear homeostasis and hearing loss (D)</p> Signup and view all the answers

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

<p>To maintain a constant state of balance (C)</p> Signup and view all the answers

<p>Through changes in endolymph and perilymph ion composition (C)</p> Signup and view all the answers

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

<p>It facilitates the recycling of potassium and ionic balance (B)</p> Signup and view all the answers

<p>Perilymph has high sodium and low potassium concentrations (D)</p> Signup and view all the answers

<p>Ionic balance maintained by transport mechanisms (A)</p> Signup and view all the answers

<p>They counteract changes to maintain set points (D)</p> Signup and view all the answers

<p>Sensorineural hearing loss (C)</p> Signup and view all the answers

<p>Endolymph in the scala media (D)</p> Signup and view all the answers

<p>Cochlear dysfunction and hearing loss (C)</p> Signup and view all the answers

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

<p>Endolymph has higher potassium levels than cerebrospinal fluid (C)</p> Signup and view all the answers

<p>It enables optimal cochlear function and hearing (C)</p> Signup and view all the answers

<p>Similar composition to cerebrospinal fluid with high sodium (B)</p> Signup and view all the answers

<p>To separate scala vestibuli from the cochlear duct (A)</p> Signup and view all the answers

<p>Stria vascularis (A)</p> Signup and view all the answers

<p>By exchanging nutrients and ions selectively (A)</p> Signup and view all the answers

<p>They release neurotransmitters onto the auditory nerve (B)</p> Signup and view all the answers

<p>Reissner’s membrane (A)</p> Signup and view all the answers

<p>Allow K+ ions to flow into hair cells (B)</p> Signup and view all the answers

<p>2-3 µm (B)</p> Signup and view all the answers

<p>A positive potential in the endolymphatic space (D)</p> Signup and view all the answers

<p>Pericytes, endothelial cells, and macrophages (C)</p> Signup and view all the answers

<p>Stria vascularis (A)</p> Signup and view all the answers

<p>Transport across the apex of the cochlea (A)</p> Signup and view all the answers

<p>They facilitate direct exchange of small molecules and ions (B)</p> Signup and view all the answers

<p>Stria vascularis as sources of fixed resistance (C)</p> Signup and view all the answers

<p>Hair cells have a significant variable resistance (D)</p> Signup and view all the answers

<p>Through active transport from fibrocytes to marginal cells (D)</p> Signup and view all the answers

<p>Ion transport mechanisms across the cochlea (D)</p> Signup and view all the answers

The maintenance of a stable internal environment in the body, essential for optimal functioning.

A mechanism that counteracts changes to bring systems back to their set point.

The cochlea, a spiral-shaped structure in the inner ear, contains three fluid-filled compartments.

Fluid in the scala media, high in potassium (K+) and low in sodium (Na+).

Fluid in the scala vestibuli and scala tympani, similar to cerebrospinal fluid (CSF), high in sodium (Na+) and low in potassium (K+).

The balance of different ions (like sodium and potassium) in the cochlear fluids is crucial for hearing.

Perilymph is believed to be derived from cerebrospinal fluid (CSF).

The connection between the scala vestibuli/tympani and the subarachnoid space via the perilymphatic duct within the cochlear aqueduct.

The process by which potassium ions (K+) are moved from the hair cells to the supporting cells and the stria vascularis, then back to the perilymph.

Special junctions between cells that allow the passage of ions like potassium (K+).

A type of hearing loss caused by mutations in the Cx26 gene, which disrupts the function of gap junctions in the cochlea.

Small channels formed by proteins called connexins, found between adjacent cells in the cochlea.

The specialized tissue in the cochlea responsible for producing and regulating the composition of endolymph.

The part of the cochlear duct located beneath the hair cells, where the perilymph surrounds them.

The cochlear artery supplies oxygen and nutrients to the inner ear structures, branching off from the labyrinthine artery.

Disruptions in blood flow to the cochlea can lead to hearing loss by affecting the function of the inner ear.

Endolymph, rich in potassium (K+), and perilymph, with a different ionic composition, maintain ionic balance in the cochlea.

The stria vascularis and gap junctions play crucial roles in recycling potassium (K+) and maintaining the endocochlear potential (EP).

The balance of cochlear fluids is essential for sound perception, supporting the electrochemical gradients needed for sensory transduction.

Mutations in genes like Cx26 can disrupt ionic balance, leading to deafness.

Pendred syndrome disrupts cochlear development and ion transport, illustrating how disruptions in cochlear homeostasis lead to hearing loss.

Pendred syndrome highlights the complex interplay between genetic factors and cochlear fluid regulation, impacting inner ear function.

The spiral modiolar artery is a key blood vessel supplying the delicate organ of Corti, the primary auditory neurons of the modiolus, and contributing to the vascularization of the spiral ligament and stria vascularis.

Despite the intricate network of blood vessels supplying the cochlea, there is no direct connection between these vessels and the organ of Corti to prevent interference with sound detection. Instead, the organ of Corti receives nourishment indirectly through diffusion from nearby vascularized structures like the basilar membrane and stria vascularis.

Walter Bradford Cannon, building on Claude Bernard's work, coined the term 'homeostasis' in the early 20th century to describe the body's ability to maintain a stable internal environment.

Homeostasis is the process by which living organisms maintain a stable internal environment (e.g., temperature, pH, fluid balance) despite external changes.

Claude Bernard, a French physiologist, introduced the idea of the body regulating its internal environment in 1849, laying the groundwork for the concept of homeostasis.

Joseph Barcroft, in 1932, extended the concept of homeostasis by emphasizing the importance of a stable internal environment for higher brain function, noting the crucial role of temperature and oxygen levels.

The unique ionic composition of endolymph and perilymph is crucial for proper hearing function. This difference in concentration of ions creates an electrical gradient that supports sound transduction.

The hair cells have an important role in maintaining the ionic balance. They control the movement of ions across their membranes, contributing to the electrical potential difference between endolymph and perilymph.

This model explains how the electrical potential differences in the cochlea are generated and maintained. It involves the stria vascularis as the energy source and other structures like the basilar membrane and the spiral ligament as resistance elements.

This is a simplified model that explains how the stria vascularis pumps potassium ions (K+) into the endolymph, contributing to the positive potential in this fluid.

Gap junctions allow direct communication between cells by exchanging ions and molecules. They are essential for synchronizing the activity of hair cells and ensuring efficient sound processing.

The maintenance and balance of ions in the cochlea is crucial for hearing. Any disruption in this ionic homeostasis can affect the electrical signals generated by hair cells and lead to hearing loss.

Endolymph is a fluid found in the inner ear. It's secreted by the stria vascularis, which is known as the "battery of the cochlea." The stria vascularis is located along the outer wall of the scala media, which is one of the compartments of the cochlea.

Perilymph is a fluid similar to cerebrospinal fluid, found in the scala vestibuli and scala tympani, two compartments of the cochlea. Endolymph is potassium-rich and has a higher electrical potential, while perilymph is sodium-rich and has a lower electrical potential.

Reissner's membrane is a thin structure that separates the scala vestibuli from the cochlear duct. It's crucial for preventing the mixing of perilymph and endolymph, which could disrupt the cochlea's function.

The blood-labyrinth barrier (BLB) is a specialized blood vessel network located in the stria vascularis. It acts as a filter, preventing harmful substances in the blood from reaching the inner ear while allowing essential nutrients and ions to pass through.

The BLB is a crucial component of maintaining cochlear homeostasis. It allows the stria vascularis to maintain the high potassium concentration within the endolymph, vital for the function of hair cells.

The hair cells in the cochlea are sensory receptors that convert sound vibrations into electrical signals. When sound vibrations cause the hair bundle to sway towards the tallest stereocilium, ion channels open, allowing potassium (K+) ions from the endolymph to flow into the hair cell. This influx of ions depolarizes the cell and triggers the release of neurotransmitters, transmitting information to the auditory nerve.

Maintaining the proper balance of ions and fluids is vital for the proper functioning of the cochlea. Imbalances in these environments can lead to hearing loss and balance problems.

The fluids and ionic environment surrounding the cochlea are crucial for the proper transmission of sound information from the ear to the brain.