LESSON 30 EAR pr cortas

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Questions and Answers

Describe the composition of the tympanic membrane and the orientation of collagen fibers within it.

The tympanic membrane is made up of three thin layers of connective tissue, with collagen fibers oriented radially in the peripheral layers and concentrically in the central layer.

What are the components of the middle ear, and what type of epithelium lines the middle ear chamber?

The middle ear contains a chain of small ossicles called the malleus, incus, and stapes, which are articulated with each other and associated with muscle tissues. The middle ear chamber is lined with a simple squamous or ciliated columnar pseudostratified epithelium.

What is the function of the cochlear duct, and how is it protected within the cochlea?

The cochlear duct, a spiral structure housing the sensory organ for hearing, is protected by two perilymph-filled ramps or scales, the scala vestibuli and scala tympani, which communicate through a bony opening called the helicotrema.

Describe the lining of the cochlea and the structure involved in the production and metabolism of endolymph within the cochlea.

The cochlea is lined by a simple squamous epithelium and contains the stria vascularis, a stratified epithelium involved in the production and metabolism of endolymph. Signup and view all the answers

What is the function of the organ of Corti, and what types of cells are included within it?

The organ of Corti, located on the floor of the cochlear duct, is an epithelial complex made up of neuroepithelial cells and supporting cells. The supporting cells include five types: cells of Hensen, Deiter, outer phalangeal cells, inner phalangeal cells, pillar cells, and marginal cells. Signup and view all the answers

How are the neuroepithelial cells categorized within the organ of Corti?

The neuroepithelial cells are of two types: outer hair cells in three rows and inner hair cells in a single row. Signup and view all the answers

What are the differences in the auditory canal structure between dogs and pigs?

Dogs have a longer auditory canal structure, while pigs have a more uniform one. Signup and view all the answers

What connects the external and middle ear internally?

The tympanic membrane connects the external and middle ear internally. Signup and view all the answers

Where is the middle ear located within the body, and what fills the bony chamber of the middle ear?

The middle ear is located in a bony chamber, filled with air from the nasopharynx. Signup and view all the answers

What is the composition and function of the ossicles within the middle ear?

The middle ear contains a chain of small ossicles called the malleus, incus, and stapes, which are articulated with each other and associated with muscle tissues. Signup and view all the answers

What is the function of the inner ear, and what are its components?

The inner ear is the portion where auditory and spatial sensations are collected, and is composed of the osseous labyrinth and membranous labyrinth. Signup and view all the answers

What is the role of the helicotrema within the cochlea?

The scala vestibuli and scala tympani within the cochlea communicate through a bony opening called the helicotrema. Signup and view all the answers

Describe the structural features of pillar cells and their role within the cochlea.

Pillar cells are triangular cells with a wide base on the basement membrane and a thin conical body. They configure the inner tunnel and the outer pillar cells are attached to hair cells, providing structural support within the cochlea. Signup and view all the answers

Explain the composition and function of the tectorial membrane.

The tectorial membrane is formed from interdental cells and consists of homogeneous, medium-density keratinized layers. It is associated with stereocilia and connected to the bone tissues of the modiolus. Its function includes coupling to hair cells and aiding in the transmission of sound waves. Signup and view all the answers

What are the distinguishing characteristics of the vestibule, and what structures does it contain?

The vestibule is a hollowed area in the petrous temporal bone that houses the utricle and saccule. It contains maculae, which are specialized receptors, and gelatinous cupulas. Signup and view all the answers

Describe the orientation and composition of the utricle and saccule within the inner ear.

The utricle is a membranous diverticulum with a hook-shaped orientation and contains the macula saculi. The saccule is also a membranous diverticulum with a kidney-shaped orientation and contains the macula sacculi. Both structures are covered with neuroepithelial cells. Signup and view all the answers

Explain the role and composition of the otoliths within the inner ear.

Otoliths are polyhedral concretions of calcium carbonate located in the apical area of the cupula, beneath the hair cells. They play a role in the detection of linear acceleration and gravity. Signup and view all the answers

What are the functions of the semicircular canals, and what structures do they contain?

The semicircular canals originate from the vestibule and host membranous semicircular canals. They contain cristae ampullares and are filled with cerebrospinal fluid. Their functions include sensing rotational movements and aiding in the maintenance of balance. Signup and view all the answers

Explain the arrangement and characteristics of cilia and stereocilia within the inner ear.

Cilia and stereocilia are arranged in the cupula, with type I cells being globose and having highly developed 92+2 cilia and stereocilia. Type II cells are columnar and have large proportions of 92+2 cilia and stereocilia. Signup and view all the answers

What are the primary functions of the hair cells within the cochlea, and how are they associated with the tectorial membrane?

The primary functions of the hair cells include responding to acoustic waves and transmitting vibrations to the chain of ossicles in the middle ear and to the round window in the cochlea. They are associated with the tectorial membrane, which aids in the detection and transmission of sound waves. Signup and view all the answers

Describe the composition and role of the Hensen's cells within the cochlea.

Hensen's cells are tall columnar cells with few organelles that define the outer tunnel. They rest on the basement membrane, have basal nuclei and abundant cytoplasmic organoids. Their role includes contributing to the structural integrity of the cochlear tunnel. Signup and view all the answers

Explain the function and composition of the organ of Corti within the cochlea.

The organ of Corti consists of neuroepithelial cells known as hair cells, transformed neurons, and elongated columnar cells with acidophilic cytoplasm and euchromatic nuclei. It also contains stereocilia in the apical portion and is embedded in phalangeal cells. Its function includes transducing sound vibrations into electrical signals. Signup and view all the answers

What are the specialized receptors within the maculae, and what structures do they contain?

The maculae contain specialized receptors known as neuroepithelial cells, supporting cells, gelatinous cupulas, and otoliths. These structures play a role in detecting linear acceleration and gravity. Signup and view all the answers

Explain the functions of the inner ear, including its role in balance, orientation, and response to acoustic waves.

The inner ear functions to sense balance and orientation, respond to acoustic waves, and transmit vibrations to the chain of ossicles in the middle ear and to the round window in the cochlea. Signup and view all the answers

Study Notes

The length of the auditory canal and the sinuosity of light vary between animal species, with dogs having a longer structure and pigs having a more uniform one.
The auditory canal is closed internally by the tympanic membrane, which connects the external and middle ear.
The tympanic membrane is made up of three thin layers of connective tissue, with collagen fibers oriented radially in the peripheral layers and concentrically in the central layer.
The middle ear is located in a bony chamber, filled with air from the nasopharynx and lined with a simple squamous or ciliated columnar pseudostratified epithelium.
The middle ear contains a chain of small ossicles called the malleus, incus, and stapes, which are articulated with each other and associated with muscle tissues.
The inner ear is the portion where auditory and spatial sensations are collected, and is composed of the osseous labyrinth and membranous labyrinth.
The cochlea, which is part of the inner ear, contains the cochlear duct, a spiral structure housing the sensory organ for hearing.
The cochlear duct is protected by two perilymph-filled ramps or scales, the scala vestibuli and scala tympani, which communicate through a bony opening called the helicotrema.
The cochlea is lined by a simple squamous epithelium and contains the stria vascularis, a stratified epithelium involved in the production and metabolism of endolymph.
The organ of Corti, located on the floor of the cochlear duct, is an epithelial complex made up of neuroepithelial cells and supporting cells.
The supporting cells include five types: cells of Hensen, Deiter, outer phalangeal cells, inner phalangeal cells, pillar cells, and marginal cells.
The neuroepithelial cells are of two types: outer hair cells in three rows and inner hair cells in a single row.
Hensen's cells: tall columnar cells with few organelles, rest on basement membrane, define the outer tunnel, have basal nuclei and abundant cytoplasmic organoids.
Outer phalangeal cells (Dieter cells): very elongated, basal nucleus, abundant cytoplasmic organoids, excavation in apical area for corresponding hair cells.
Inner phalangeal cells: similar to outer phalangeal cells, house inner hair cells in apical area.
Pillar cells: triangular cells, wide base on basement membrane, thin conical body, configure inner tunnel, outer pillar cells attached to hair cells.
Marginal cells: columnar cells, form a row on tympanic lip of limbus.
Organ of Corti: neuroepithelial cells are hair cells, transformed neurons, elongated columnar cells, euchromatic nucleus, acidophilic cytoplasm, stereocilia in apical portion, embedded in phalangeal cells.
Structural features of hair cells: stereocilia in W pattern for outer hair cells, V pattern for inner hair cells, coupled to tectorial membrane, surrounded by mitochondria and smooth endoplasmic reticulum.
Basement membrane associated with presynaptic bulbs, formed by ganglion cells in fibers of the acoustic nerve, located below hair cells.
Tectorial membrane: formed from interdental cells, homogeneous, medium-density keratinized layers, associated with stereocilia, connected to bone tissues of modiolus.
Vestibule: hollowed area in petrous temporal bone, houses utricle and saccule, contains maculae, specialized receptors, and gelatinous cupulas.
Utricle: membranous diverticulum, contains macula saculi, hook-shaped, oriented vertically, covered with neuroepithelial cells.
Saccule: membranous diverticulum, contains macula sacculi, kidney-shaped, oriented horizontally, covers neuroepithelial cells.
Maculae: specialized receptors, contain neuroepithelial cells, supporting cells, gelatinous cupulas, and otoliths.
Cilia and stereocilia: arranged in cupula, type I cells are globose with highly developed type 92+2 cilia and stereocilia, Type II cells are columnar with large proportions of 92 +2 cilia and stereocilia.
Semicircular canals: originate from vestibule, host membranous semicircular canals, contain cristae ampullares, and are filled with cerebrospinal fluid.
Crystals (otoliths): polyhedral concretions of calcium carbonate, located in apical area of cupula, beneath hair cells.
Functions: sense balance and orientation, respond to acoustic waves, transmit vibrations to the chain of ossicles in the middle ear, and to the round window in the cochlea.

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Description

Explore the anatomy and functions of the ear, including the reception, transmission, and transformation of acoustic waves. Learn about the specific structures integrated in the external, middle, and internal ear.