PSY 102 Grand Canyon Week 2 Discussion 2

Select a sense organ, and trace a stimulus’s path from outside the body to the brain. What did you learn about the sensory organ you selected that you did not know before? Additionally, complete the “Try It” activity on page 87 of the text. Were you surprised by the results? Why or why not?

 

ADDITIONAL INFORMATION 

Sensory organs and stimuli paths

Introduction

The senses of taste, smell and touch are the most well-known. But there is another sense that we don’t usually think about: vision. The visual system in our brain is made up of many different parts that work together to allow us to see the world around us. We will explore these components and their functions in this article:

Visual Stimuli

Visual stimuli are light waves that stimulate the retina, a part of the eye responsible for detecting light. The retina contains photoreceptor cells, which convert photons into electrical signals that can be transmitted through the optic nerve to the brain, where they are interpreted as visual images.

The photoreceptor cell, also known as rod or cone cells (depending on what color it’s detecting), detects polarized light—light with one side brighter than another. Rods detect blue and green wavelengths; cones detect red/green/yellow colors; there are also two types of cones: long wavelength sensitive (LWCS) and short wavelength sensitive (SWS).

Photo receptor cells (cones and rods)

Cones are responsible for color vision, while rods are responsible for black and white vision. Rods can detect motion better than cones, which makes them useful for night vision and tracking moving objects.

When you look at something with your eyes open, the light entering your eye has to pass through two layers of cells: the outermost layer (the cornea) is transparent to light; then it passes through a layer that reflects some of it back out into space. This is why we see so much glare in bright conditions—reflective surfaces like sand or water cause lots of reflections on this first layer before they reach our eyes!

Bipolar Cells

Bipolar cells are found in the retina, and they transmit information from rods and cones to ganglion cells. The bipolar cells are more sensitive than rods and cones, so they can detect contrast and movement. They also help us see colors by sending signals through their axons to other parts of our brain where we interpret colors based on what we see with our eyes (such as blue vs red).

Retinal Ganglion Cells

• Retinal Ganglion Cells

• Transmit signals to the brain.

• Receive signals from the retina.

• The brain interprets these signals as vision

Optic Nerve

The optic nerve is a bundle of nerve fibers that carries information from the eye to the brain. Information from your retina is carried by axons of retinal ganglion cells (RGCs) towards your optic nerve, which then passes it on to other parts of your brain. This process allows you to see things like colors, shapes and movement in front of you!

• How do RGCs send information?

RGCs are small cells found in our eyes that send signals back and forth between them and other parts of our nervous system such as muscles or glands; this helps us see things clearly because we can tell where objects are located based off how bright they look when viewed through an optical device like glasses or contact lenses (if needed).

Optic Chiasm

The optic chiasm is a structure in the brain that separates the left and right sides of your brain. It’s responsible for processing visual information, so it’s at the center of all your visual experiences.

The optic chiasm is located in your brainstem—the part of your nervous system below your skull and above your spinal cord. The optic chiasm helps you see things by separating light from dark or color from gray.

Left and Right Lateral Geniculate Nuclei

The optic tract carries visual information from the retina to the lateral geniculate nucleus. The lateral geniculate nucleus is located in the thalamus, a relay station for sensory information between the cerebral cortex and brainstem. It receives signals from photoreceptors in your eye and sends them along to your visual cortex where you can see them as images.

Cranial nerves III, IV, VI

Cranial nerves III, IV, and VI are sensory nerves that travel through the brainstem to the cerebellum. These cranial nerves affect muscle tone.

Cranial nerve III is involved with eye movement. It carries information from the visual cortex of your brain to your eyes (which have no muscles). This information allows you to see things that are moving or blinking at you—like when someone is blinking their eyes rapidly or slowly moving past you on a train platform!

Cranial nerve IV sends signals about smell back up towards your nose so that we can smell things like food cooking in our homes or pungent odors from toxic waste sites.* The part of this nerve responsible for sensing smells might actually be located near where we taste foods on our tongues instead of just detecting them through taste buds alone; therefore some scientists think it makes sense for us humans not only have two sets each consisting of one pair per side but also two different kinds – one type being “wet” while other type “dry” based upon whether liquid reaches mouth first before solid object enters mouth then later travels further down throat before reaching lungs where gases produced during breathing process exit via mouth cavity again.*

Takeaway:

The visual system is a complex system that allows us to see. It has three major pathways, each with multiple parts:

• The first pathway begins at the eye and ends in the brain, where it’s processed by visual cortex. This pathway is important for processing simple images like faces and letters; it allows us to recognize objects we’ve seen before but not recognize new ones.

• The second pathway connects directly from your eye’s photoreceptors (light-sensitive cells) to your optic nerve fibers—these nerves carry information about what you’re seeing straight into your brain where it can be processed further by other areas of cortex.* Visual stimuli are processed in these two parts of cortex before they’re sent through specific parts of striate cortex responsible for recognizing objects like faces or houses.* Finally, some messages may reach other parts of parietal lobe (behind eyeball) if needed–for example when object appears close enough so it’ll overlap part way into field where vision occurs; however this area isn’t necessary for normal functioning since most things will always appear relatively stationary regardless whether moving closer or farther away from viewer

Conclusion

In this article we have seen the many different sensory organs in the head and their functions. We have also learned about how these different parts of the brain work together to give us information on our environment. The next step is to use this knowledge to solve problems, think creatively, and make decisions based on what we see and hear around us every day!