CHAPTER 6 - Vision and Chemoreception

Light

A form of electromagnetic radiation, that can be conceptualized as a stream of tiny, massless packets of energy called photons

We see a continuum from________ to_______

• 400nm (purple)

• 700 nm (red)

Cornea

The clear, dome-shaped outer layer of the eye that covers the iris and pupil

Pupil

The opening at the center of the iris through which light passes

Lens

A clear, transparent, biconvex structure located behind the iris and pupil that focuses light rays onto the retina, enabling us to see clearly.

Retina

A clear, transparent, biconvex structure located behind the iris and pupil that focuses light rays onto the retina, enabling us to see clearly.

Ganglion cells

The projection neurons of the vertebrate retina, conveying information from other retinal neurons to the rest of the brain

Intermediate cells

Also known as bipolar or amacrine cells to process and transmit signals from photoreceptors (rods and cones) to ganglion cells

Photoreceptor cells

Specialized light-detecting cells (rods and cones) that convert light into electrical signals that the brain uses to form images.

Photopic (daytime) vision

• Cones

• Fovea

Cones

Photoreceptor cells in the retina that are responsible for color perception and high visual acuity in bright light conditions

Fovea

Where the human eye is able to best distinguish visual details.

Scotopic (night) vision

• Rods

• Retina Periphery

Rods

Photoreceptor cells in the retina that are highly sensitive to light and responsible for low-light vision

Retina Periphery

the area of the retina responsible for encompassing everything outside the central macula, including the edges of your vision.

Myopia

Also known as nearsightedness is a common eye condition where distant objects appear blurry while close objects remain clear due to the eyeball being too long or the cornea (the clear front cover of the eye) is too curved.

What kinds of lens is used for Myopia?

Biconcave lens used to correct

Hyperopia

Also known as Farsightedness is a common eye condition where close object appear blurry due to the Eyeball being too short or cornea being flatter than normal

What kinds of lens is used for Hyperopia?

Biconvex lens used to correct

Trichromatic theory

• States that we perceive colors because we have three types of photoreceptor cells cones that each have photopigments sensitive to different wavelengths of light.

  • Blue (short)

  • Green (medium)

  • Red (long)

    

Opponent process theory

Ganglion cells in the retina and cells in the thalamus send different color signals depending on if they are excited or inhibited.

• R+G– sends a signal for red when excited and green when inhibited.

• R–G+ sends a signal for green when excited and red when inhibited.

• Y+B– sends a signal for yellow when excited and blue when inhibited.

• Y–B+ sends a signal for blue when excited and yellow when inhibited.

Visual Pathway

• Axons from ganglion cells make up the optic nerve., which then travels to the LGN of the thalamus.

  

Primary visual cortex

The first area of the brain's visual cortex to receive and process visual information, relayed from the retinas.

Simple Cells

Sensitive to lines of specific orientation on their receptive fields

Complex cells

Sensitive to lines of specific orientation moving in a specific direction

Hypercomplex cells

Sensitive to lengths and angles of lines

Figure 6.14: Visual Pathways

Inferior Temporal Lobe

Part of the brain involved in complex visual processing, including recognition of objects and faces.

Primary Cells

Respond to simple shapes like squares, spots, and circles.

Elaborate Cells

Respond to complex shapes, textures, and shapes with specific colors. Damage to these cells can result in agnosia.

Face-Selective Cells

Respond to faces, faces of specific orientations, and specific people’s faces. Damage to these cells can lead to prosopagnosia (inability to recognize faces).

Figure 6.19: Olfactory System

Taste Sensation and Perception (_______)

Gustatory

Tastants

Chemicals associated with different flavors

• Sweet, salty, sour, bitter, umami (taste of glutamate)

Taste Papillae

Bumps on the tongue that contain taste buds

Explain taste

1. Trenches around papillae collect saliva and tastants.

2. Papillae contain taste receptor cells where transduction takes place.

Supertasters have more…

more papillae and are more sensitive to bitter flavors.

According to the video describing features of the Human Genome Project, findings from this project have helped in the prevention of some diseases.

1. True

2. False

1. True

Genetically modified organisms only include food products.

1. True

2. False

2. False

Which of the following is NOT one of Darwin’s Postulates?

1. Over reproduction

2. Advantage

3. Nature vs nurture

4. Variation within the population

5. Modification through descent

6. Competition

3. Nature vs nurture

1. Where is the blind spot located within the eye?

   1. Fovea

   2. Lens

   3. Optic nerve

   4. Iris

3. Optic nerve

1. The fovea is where the most rods are located and supports peripheral vision.

   1. True

   2. False

2. False