Question

The light stricking the retina generates nerve impulse. Which of the following options correctly describes the path of light? (a) Photosensory celis \(\rightarrow\) Bipolar neurons \(\rightarrow\) Ganglionic cells \(\rightarrow\) Sensory nerves (b) Sensory nerves \(\rightarrow\) Bipolar neurons \(\rightarrow\) Ganglionic cells \(\rightarrow\) Photosensory cells (c) Sensory nerves \(\rightarrow\) Ganglionic cells \(\rightarrow\) Bipolar neurons \(\rightarrow\) Photosensory cells (d) Photosensory cells \(\rightarrow\) Ganglionic cells \(\rightarrow\) Bipolar neurons \(\rightarrow\) Sensory nerves

Short answer

The correct pathway of light-induced signals is option (a): Photosensory cells \(\rightarrow\) Bipolar neurons \(\rightarrow\) Ganglionic cells \(\rightarrow\) Sensory nerves.

Step-by-step solution

Understanding Retinal Signal Processing

The process of sight begins when photons of light enter the eye and are detected by photosensitive cells in the retina called photoreceptors. These cells then transmit the signal in a specific pathway through other neural components before reaching the brain. Understanding the correct sequence is essential for answering this question.

Analyzing the Options

Each option provides a sequence of cells or neural structures through which light-induced signals could travel. To find the correct path, we must recall the actual sequence of nerve signal transmission from the photoreceptors in the retina to the brain.

Recalling the Correct Pathway

The correct pathway of light-induced signals in the retina is: Photoreceptors (Photosensory cells) capture the light and convert it into a neural signal. This signal is then processed by Bipolar cells followed by Ganglion cells. Finally, the axons of the Ganglion cells form the optic nerve (Sensory nerves) that carries the signal to the brain.

Determining the Correct Option

From the given options, the one that matches the correct sequence is (a) Photosensory cells \(\rightarrow\) Bipolar neurons \(\rightarrow\) Ganglionic cells \(\rightarrow\) Sensory nerves. This is the accurate path that the light-induced signal takes to reach the brain after hitting the photoreceptors.

Key concepts

Photoreceptors

The human eye is a complex organ capable of converting light into a signal the brain can understand. At the heart of this process are specialized cells known as photoreceptors. Think of these as the eye's camera sensors, capturing light's presence, intensity, and color.

There are two primary types of photoreceptors in the retina: rods and cones. Rods are incredibly sensitive to light and are crucial for vision in low-light conditions, but they cannot detect color. Cones, on the other hand, are less sensitive to light but allow us to appreciate the full spectrum of colors in well-lit conditions.

The journey of visual perception starts here, as photoreceptors convert light photons into electrical signals. It's a sophisticated procedure involving the transformation of physical energy (light) into a form of energy the nervous system can process (neural signals).

Neural Signal Transmission

Once the photoreceptors have done their job, the baton is handed off to the next set of players in this relay race of vision—the neural signal must be transmitted to the brain. But first, it needs to be meticulously processed.

The signal undergoes an intricate voyage. After being generated in the photoreceptors, it passes through several types of neurons within the retina. Bipolar cells are the first to receive the signal. They act as direct messengers, passing the signal on to the ganglion cells, which could be seen as the eye's output units.

Information Sharpening

On its way, the signal is 'sharpened' by horizontal and amacrine cells. These cells fine-tune the visual information, enhancing contrast and helping us see edges more distinctly. This processing is essential to transform a simple snapshot of light into a detailed image our brain can understand.

Optic Nerve

The final leg of the journey to visual perception involves the optic nerve. After the retinal ganglion cells process the incoming signal, their axons come together to form this crucial cable of neural fibers. Think of the optic nerve as the high-speed internet connection transmitting data packets (in this case, visual information) between your eye and your brain.

These fibers extend from the back of each eye, and remarkably, they partially cross paths at a juncture known as the optic chiasm. This crosslink allows visual information from both eyes to be combined and interpreted, giving us the ability to perceive depth and enjoy a three-dimensional understanding of our world.

The work of the optic nerve doesn't stop at mere transportation. It's part of a sophisticated network that constantly communicates with the brain to adjust the brightness, focus, and field of vision, enabling us to see the world in all its vivid detail and motion.