The Ear (Audition) by Gretchen Romin, Kyla Blair and Andrea Cata Ro and Garrett Tonge

The Ear (Audition, sense of sound)


When an object makes some kind of noise, it produces vibrations (also known as waves) that travel throughout the air. These vibrations enter to the ear and move to the middle ear to hit the eardrum, causing it to vibrate and develop a series of vibrations to the smallest bones, There are three bones of the ear. The three bones are the incus, malleus and the stapes. They are part of the middle ear and are infact the smallest bones in the human body. The purpose of the three bones is to connect to the hinges and the levers that carry vibrations from the eardrum to the inner ear in the body: the hammer, the anvil and the stirrup. After the vibrations hit the stirrup, they move through cochlea (the inner ear). The cochlea is fluid-filled and contains small nerve endings (known as cilia). When the vibrations reach the cochlea, it makes the fluids move and so do the cilia. The cilia change the vibrations into messages that are sent to the brain. The brain processes the message and recognizes what sound is the vibration acquired. It recognizes what has been stored in the memory, making you identify the sound.

When asked to explain how the ear works, much information was missed during our groups efforts, though main ideas were recognized. In our attempt we were able to identify that when a sound is made vibrations are produced and travel through a canal and encounter three small bones and the eardrum. We were also able to identify the fact that signals are then transferred to the brain where they are processed and then recognized. However, our group was not aware of such details as the inner, outer and middle ear, the names of the three small bones, or how to correctly identify the exact order of the process in which sound travels through the ear.

Sources:
http://library.thinkquest.org
http://en.wikipedia.org/wiki/Ear

The Sense of Smell - Anthea, Hayley & Nicole

The Sense of Smell

Initial Deductions
Our initial beliefs were that our nose detects odor molecules that travel through the air, and little feelers in our nose detect these odors and the molecule fit into little smell centers within our nose. These smell centers then send a message to our brain, which processes the resulting information to the sensation of smell. Our initial deduction is correct, although it is a very simplified version of the process that occurs during the sense of smell.

Detailed Description
The sense of smell depends on tiny sensory receptors called chemoreceptors within the nose that respond to odor molecules. These chemoreceptors are located in a patch of tissue high in the nasal cavity called the olfactory epithelium. This patch of tissue is made up of three types of cells: sensory neurons, basal cells and supporting cells between them.

There are millions of sensory neurons, each of which have tiny filaments (cilia) extending from a handle. This handle is located at the tip of the olfactory neuron and the cilia project from the handle directly into the atmosphere. This is the only part of the brain that projects into the atmosphere. The cilia contain olfactory receptors, which are specialized proteins that bind odor molecules. A large multi-gene family encode for these olfactory receptors. Each receptor has a pocket that is just the right shape to bind either a specific molecule or a group of structurally similar molecules. The interaction of the right molecule with the right receptor causes the receptor to change its shape. This change provides an electrical signal that goes first to the olfactory bulb and then to the areas of the brain that convert the electrical signal into a smell.


Interesting Facts

• The sense of smell plays a vital role in our sense of well-being and quality of life.
• Everyone has his or her own unique odor-identity or “smell fingerprint.
• No two people smell the same odor the same way. In other words, a rose may smell sweeter to some people than to others.
• The average human being is able to recognize approximately 10,000 different odors.
• Our sense of taste is greatly influenced by our sense of smell.
• A larger portion of the brains of animals and fish are devoted to the sense of smell than that of humans.
• Your nose can smell directionally, telling you where an odor originates.
• Your sense of smell is least acute in the morning; our ability to perceive odors increases as the day wears on.
• A woman’s sense of smell is keener than a man’s.

Resources
http://www.senseofsmell.org/feature/smell101/lesson1/01.php
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/O/Olfaction.html

The Somatosensory System (Touch) by Andrea, Katie, Kaitlynd, and Christian

The Sense of Touch

Initial Deductions

Although our initial deductions of the sense of touch were not incorrect, neither were they flushed out or with strong basis. We believed the sense of touch to be the result of a relation between nerves and the brain, which although true, is involved in a more complex system then we had previously thought. The relation between the nerves, receptors, somatic pathway and the brain was where we chose to focus our investigation.

The Somatosensory system 

The somatosensory system comprises the somatic system, or in colloquial terms, touch. It is formed from the skin, skeletal muscles, organs, cardiovascular system and bones. The skin plays the largest role in the somatic system, namely the dermis which is the bottom layer of skin where small nerve endings relay information to the spinal system (nervous) and then to the brain. Heat, cold, pain and pressure are the most common of the twenty nerve endings, or receptors, in our dermis.

The information gathered from the receptors is relayed via sensory nerves and it is known as the somatosensory pathway. It is comprised of two long neuron pathways with three major points. The first is the dorsal root ganglion located at the base of the spine. The transmission then reaches the brainstem and the root of the thalamus. The last point for the somatosensory pathway transmission is located in the postcentral gyrus of the parietal lobe (end of the thalamus gland).Locations in the brain are associated with each receptor, and as such the distinguishment of pain, pressure, heat, cold, etc are finalized in the brain.

Interesting facts

• The middle back is the least sensitive
• Most sensitive areas: hands, lip, face, neck, tongue, fingers, feet
• You shiver to warm up
• 100 touch receptors in each fingertip
• Young animals that have been touched more: grow faster, develop stronger immune   responses, more playful, less fear, tolerate stress better, greater resistance to physical harm
• Children that have been cradled or held more: gain weight, grow faster, start crawling, walking and grabbing earlier, more alert and active and sleep more soundly, develop stronger immune systems and have high IQ’s

Resources

• http://whalonlab.msu.edu/Student_Webpages/Babies/The%20Sense%20of%20Touch.htm
• http://library.thinkquest.org/3750/touch/touch.html
• http://en.wikipedia.org/wiki/Touch
  

The Sense of Sight by Karan, Steph, Lesley, Wendy & Jeannie

THE INCORRECT INFORMATION
Our initial thought was that for sight to occur, it mainly depended on the cornea, which was located at the back of the eye and responsible for processing the image we see. It flipped the image upside-down, and then passed it along to the brain. In fact, it is the retina, partnered with the optic nerve, that does this function. We had also excluded the important role of light during the act of seeing, as well as neglected various parts of the eye.

DETAILED DESCRIPTION OF SIGHT
Eyes are often compared to have the same functionality as a camera would. The camera as we know it, uses lens and film to produce an image taken within its visual field. The same concept can be applied to the eye. Light first enters through the cornea, a clear tissue in the front of our eyes, which then passes through our pupils. The pupils are similar to the lens or the shutter of a camera in that it directs how much light enters our eyes. The pupils would widen when it is dark to allow more light in and shrinks when there is an excess of light. Surrounding the pupil is a coloured ring called the iris, which is a muscle fibre that helps the pupil change size. When we look at an object, the light enters through the pupil which is then focused on the retina (back of the eye) via the pupil and the cornea. The retina is referred to as the film of the camera. This retina is what captures the image in our visual field. The retina is usually lined with photoreceptors , which change light rays into electrical impulses which are then sent to the brain through the optic nerve.

The optic nerves are connected to the optic chiasma where the inner (nasal) half of each retina crosses to the opposite side, and the outer (temporal) half stays on the same. Like other sensory and motor projection systems in the body, each side of the body is represented by the opposite side of the brain. The optic chiasma leads to the visual cortex where there is a projection area in each hemisphere containing a "map" of visual space. What the retina reads will be mapped on the projection area, and thus vision occurs. In other words, the images we see are flipped upside down and are then flipped right side up when it is received in our brain.

BIBLIOGRAPHY

• Diagram I courtesy of MedlinePlus
• Diagram II courtesy of Karan Patel
• http://www.accessscience.com
• http://www.aoa.org/
• http://health.yahoo.com/vision-videos
• http://www.howstuffworks.com/eye.htm
• http://www.pasadenaeye.com/
• http://www.sightsavers.org
• Steve Parker, The Human Body, Eyes and Vision: The Sequence of Vision, First American Edition, 2007, 92-93.

Exercise 2: The Five Sense, Taste

The Sense of Taste

By: rebeca, margarita, claudia, annika

One theory was provided as to how our sense of taste can identify different tastes. For example, how is it possible that we are to differentiate between a piece of candy versus lemonade? The theory states that different taste buds include a possible way of separating bitter, sweet, sour, and salty. However, a recent experimentation has found a new discovery and has added a fifth sensation to the grouped taste buds. It is known to be called Umami. Umami was found out by a Japanese scientist and the taste is found in many of the savory content of seaweed. Glutamic acid was isolated as a fifth tastebud. 

The bitter taste in our mouth is known to be present due to  TAS2R38 (our taste receptors in type 2) couple to a G-protein. The genetics of the dominance of bitter taste can be studied by two substances: phyenylthiocarbamide (PTC) nd 6-n-propylthioracil (PROP) which determines the strength of bitterness due to a human's genetics. Sweetness is due to G protein taste receptors which are coupled with G protein gustducin. Moreover, there must be two sweet receptors to be activated in order for the brain to recognize a sweet sensation. When sodium ions are received in the mouth, this is particularly why we taste a saltiness in the mouth. Lastly, sourness is due to hydrogen ions.

Taste is a part of the central nervous system. Taste buds are also known as receptor cells which allows one to be able to distinguish a specific taste. Inside each taste bud is a gustatory receptor cell where approximately 50 receptor cells make up one taste bud. Inside each gustatory receptor cell includes something called gustatory hairs which reach through to the outside of the tongue by the taste pore. These hairs interact with a mixture of saliva and molecules, allowing humans to be able to taste. Then a stimulus activates a gustatory impulse. Next, the receptor cells synapse with neurons and transmit these signals to the section of the brain which interpret the specific taste. 

The Senses System Model

Exercise Two: Perception and Cognition Research

In the first class, your Project One group developed a system model for one of the senses, to the best of your knowledge. Expand your knowledge by researching the sense in question, and post the results of your research to the blog.

Make your post succinct. It should no more than three paragraphs, and should make use of images where appropriate. Specifically identify any misconceptions in the mental model developed in class and correct them. Informally cite any sources employed.

Only one post per group is necessary. Please include the name of all of your group members in the title of your post.

Exercise Two is due at 08:30 on Wednesday, January 14th.