GDES1B26 — FW2010 — 14

Your sense of touch is found all over your body because it originates in the bottom layer of your skin known as the dermis. The dermis is made up of many tiny nerve endings that carry information about things to come into contact with your body to the spinal cord, which signifies the brain where the feeling is registered.

The nerve receptors detects temperature, pain, pressure or touch and sends the message to your brain. Without it, you would not be able to tell if something hurts!

Some parts of your body (such as the tongue), are more sensitive than others because they have more nerve endings. The sides of your tongue is very sensitive to pain but not so much hot or cold, which is why it is easy to burn your mouth when you eat something very hot. Fingertips are also very sensitive; blind people use it to read Braille. There are about 100 touch receptors in each of your fingertips. Other sensitive areas of your body include lips, face, neck, feet and hands. The least sensitive part of your body is the middle of your back.

http://en.wikipedia.org/wiki/Sense

http://library.thinkquest.org/3750/touch/touch.html

ESP

ESP is the acronym and commonly spoken form for ExtraSensory Perception. This refers to a phenomenon in which a person receives sensory input directly to the mind, without utilizing the traditional five senses. ESP can include multiple phenomena including telepathy (mind-reading), precognition (future sight), clairvoyance (viewing a distant location), retrocogniton (seeing past events one did not witness) and non-ocular vision (seeing covered objects and/or with eyes closed). Scientific authority currently rejects the existence of ESP, though research into it is ongoing in several fields. As such, there is no conclusive evidence that ESP or any phenomena related to it actually exists, as claims are often based on anecdotal evidence and controlled tests most often fail to document any indication of ESP and are nigh impossible to accurately reproduce. Since the existence of the sense has not been proven, no theories or models exist on how it might work. However, if ESP does exist, the logical method for it to work would be for the brain or some unclassified sensory organ to receive some form of outside input that cannot be detected by the other five senses or any of our current technology. The fact that only a small number of people claim to possess ESP indicates that if it is real, the sense could be recessive, the result of rare mutation, a learned or born ability or any number of other things. The field of parapsychology is devoted to the study of paranormal psychic phenomena, ESP among them. Individuals who claim to possess and use ESP are often referred to as Telepaths, Psychics, Mentalists, Fortune-Tellers or Clairvoyants

• Not only does the nose allow you to smell, it is also largely responsible for why you are able to taste things; as well, it is the main opening to your respiratory system
• Parts of the nose include: the nostrils and the nasal passages, which are separated by the septum (a wall, close to your skull, made up of thin pieces of bone); cartilage (material that is firmer than skin or muscle, but still quite flexible); and the nasal cavity (a space behind your nose, in the middle of your face that connects with the back of your throat and is separated from your mouth by the palate)
• Your nose allows for both inhalation and exhalation
• When inhaling, air enters the nasal passages, travels into the nasal cavity, down the back of your throat into the trachea (windpipe) and into the lungs; exhaling is the process in reverse
• The nose is also required to warm, moisten, and filter air before it progresses towards the lungs
• To warm up and moisten the air that is inhaled, a mucous membrane (a moist, thin layer of tissue) lines the inside of the nose and produces mucus; although gross, mucus traps germs, dust, and small particles that would otherwise irritate your lungs.
• The hair that is inside the nose traps larger particles such as dirt and pollen
• Sneezing occurs when your body wants to get rid of these unwelcome particles; they can be spent speeding out of your nose at approximately 100 mph with a single sneeze
• There are microscopic hairs that exist farther back in the nose and air passages called cilia; cilia move back and forth to carry mucus away from the sinuses, back of the throat, and out of the lungs
• The olfactory epithelium, located on the roof of the nasal cavity contains special receptors that are sensitive to odour molecules travelling through the air we breathe in
• There are at least 10 million infinitesimal receptors in your nose and hundreds of different kinds to detect certain odours and odour molecules; the brain is responsible for interpreting a combination of receptors to distinguish one from about 10,000 other smells
• The olfactory bulb, underneath the front of your brain (see diagram), receives signals that travel along the olfactory nerve when smell receptors are stimulated; in turn, these signals travel to other parts of the brain to be interpreted into a recognizable smell
• The process of identifying smells is the way the brain tells you about your environment (e.g. burning toast; your nose interprets the smell and you know you need to check on your toast)
• Taste is very closely linked to smell; it’s extremely difficult to fully experience taste without help from the nose

Citation

http://kidshealth.org/kid/htbw/nose.html#

http://www.revisionrhinoplasty.com/anatomy.html

http://www.britannica.com/EBchecked/topic/420420/nose

Clinical Anatomy of the Nose, Nasal Cavity, and Paranasal Sinuses, Johannes Lang

HEARING

How the ear works (video)

The ear is an extraordinary organ; it picks up the sound and translates it into nerve impulse – the type of signal that the brain can understand.  The peculiar thing about hearing is that it is a completely mechanical process. Other senses such as vision, taste, and smell involve chemical reactions. Hearing, however, is based solely on physical movement.

First of all, the sound travels as a vibration of air compressions. Pinna is a part of the outer ear which catches the sound; it has a number of curves which help to determine where the sound comes from. To find out the horizontal position of the sound one’s brain compare the signals that come from both ears.

When the sound waves travels into the ear canal and hit the ear drum (a tightly stretched membrane), the pressure they create is converted into vibrations of the same frequency. The ear drum is positioned between the ear canal (outer ear) and middle ear; it is also connected to the throat via Eustachian tube which allows maintaining the same atmospheric pleasure in the middle ear as in the outer ear.

Ossicles are a group of small bones in the middle ear designed to transmit the sound signal from ear drum to the fluid in the cochlea. Ossicles also amplify the signal so it can go through the liquid in the inner ear and be translated to the nerve impulses (more about the system of amplification).

The function of the cochlea, which is considered to be an inner ear, is to transform the mechanical sound signal into nerve impulses. The cochlea is filled with fluid, through which the vibration passes, and is lined with hair-like nerve cells which vary in length and degree of resilience so that the different cells will be sensitive to specific frequencies. These hear cells transform the vibrations into nerve signals  which are then sent to the brain by the auditory nerve (More about how hair cells work – video).

For more information see:

http://health.howstuffworks.com/human-body/systems/ear/hearing.htm

http://www.avatar.com.au/courses/PPofM/index.html

http://www.unmc.edu/physiology/Mann/mann8.html

http://www.physicsclassroom.com/class/sound/u11l2d.cfm

http://www.ndt-ed.org/EducationResources/HighSchool/Sound/hs_sound_index.htm

Images:

http://www.freedomscope.com/wireless_stethoscope_for_the_hearing_impaired.htm

http://health.allrefer.com/pictures-images/ear-anatomy.html

http://www.cartoonstock.com/directory/s/selective_hearing.asp

In the first class, your Project One group developed a mental 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. Be prepared to briefly present your post next week.

Exercise Two is due at 12:00 on Friday, January 21.