Question

Internal ear is filled with (a) Perilymph (b) Endolymph (c) Lymph (d) Both (a) and (b)

Short answer

The correct answer is (d) Both (a) and (b).

Step-by-step solution

Analyze Options

First let's take a look at the answer choices provided. We have options: (a) Perilymph, (b) Endolymph, (c) Lymph, and (d) Both (a) and (b). The goal here is to pick the correct choice that describes what the internal ear is filled with.

Recall Knowledge

Next, recall your biology knowledge. Remember that the human ear is a complex structure with different sections. Two of these sections, the cochlea and the vestibular apparatus, are filled with two different types of fluid: the perilymph and the endolymph.

Choose Correct Answer

Given that the internal ear does contain both perilymph and endolymph, the correct answer to the question must be option (d): Both (a) and (b), meaning both Perilymph and Endolymph.

Key concepts

Perilymph

Perilymph is one of the key fluids found in the inner ear. It plays a crucial role in hearing as well as in maintaining balance. This fluid is similar in composition to cerebrospinal fluid, which surrounds the brain and spinal cord. The perilymph is located in the bony labyrinth, which is one of the two major parts within the inner ear.

Think of the bony labyrinth like a protective casing that houses the delicate structures responsible for hearing and balance. This casing is filled with perilymph, which acts as a cushion, protecting the delicate membranes of the inner ear from damage.

Moreover, the perilymph is involved in the transmission of sound vibrations. It receives these vibrations after they pass through the ear drum and the ossicles (tiny ear bones), and then it relays them to the cochlea where they can be converted into nerve signals.

• Location: Bony labyrinth
• Function: Cushioning and transmission of sound vibrations
• Composition: Similar to cerebrospinal fluid

Endolymph

Endolymph is another essential fluid within the inner ear, found in the membranous labyrinth. While it is chemically different from perilymph, both types of fluid work together to assist in auditory and balance functions. Endolymph is rich in potassium ions, which is crucial for converting mechanical signals into electrical signals in the sensory hair cells.

This fluid bathes the sensory hair cells, which are critical components for sensing both sound and head movement. When sound waves reach these cells, the endolymph's ionic composition allows for the generation of nerve impulses in response to the mechanical movement of the cells. These impulses are then sent to the brain as signals that are interpreted as sounds.

Furthermore, endolymph fills a specialized structure called the cochlear duct. It supports the complex function of detecting pitch and volume in sounds, contributing to a finely tuned hearing process.

• Location: Membranous labyrinth
• Function: Converts mechanical signals to electrical signals
• Composition: High potassium ion concentration

Inner Ear Structure

The inner ear is a vital component of the auditory system. It comprises several essential parts, each contributing to hearing and balance. The main structures are the cochlea, the vestibule, and the semicircular canals, housed in the labyrinth of the temporal bone.

The cochlea is the spiral-shaped organ responsible for detecting sound. This structure turns sound vibrations into electrical signals sent to the brain. Meanwhile, the vestibular system helps maintain balance and spatial orientation. This involves detecting changes in head position, which is crucial for day-to-day actions like walking or even sitting still.

The entire inner ear can be thought of as two intertwined labyrinths, the bony labyrinth, and the membranous labyrinth. The bony labyrinth contains the perilymph, while the membranous labyrinth is filled with endolymph. They work in harmony to control both equilibrium and auditory functions.

• Cochlea: For sound detection
• Vestibule and semicircular canals: For balance
• Labyrinths: Bony (perilymph) and membranous (endolymph)