The Five Senses

Sight
Smell
Hearing
Taste
Touch

Sight

The eye is the sense organ associated with sight,
and it detects light that is converted to electro-chemical
impulses in neurons.

Section of the Brain, and Nerves

Occipital Lobe
Once the information passes from the optic nerve to the rest of the brain,it is sent to the occipital lobe, where sight is processed.
The occipital lobe is located in the back of the brain, above the cerebellum, and forms the center of the visual perception system, according to the Centre for Neuro Skills.
Each hemisphere has its own occipital lobe; therefore, each occipital lobe processes the information sent to that specific hemisphere.
The occipital lobe controls how a person perceives sight, so damage to this brain section can result in visual field cuts, and problems identifying color or movement of an object.

Optic Nerve
When light reaches the retina in the eye and an image is created, it moves to the rest of the brain through the optic nerve.
The optic nerve is the second cranial nerve, and is the connection between the brain and eyes.
Damage to the optic nerve prevents any information from being sent from the eyes to the rest of the brain.
The Canadian Institutes of Health Research states that information from the left eye goes to the right hemisphere and vice versa; this is because the optic nerve crosses at the optic chiasm, causing the optic nerve from each eye to send its information to the opposite side of the brain.

Visual Cortex
The last part of the brain involved in sight is the visual cortex, where sensory and motor information is integrated with vision.
The Canadian Institutes of Health Research states that multiple visual pathways are involved.
For example, the ventral visual pathway controls how a person identifies objects, while the dorsal visual pathway controls a person's visual-motor response to objects.
In other words, the visual cortex allows you to realize that you're looking at a plate, for example, and then allows you to pick it up.

Major parts involved with sight

Parts	Functions
Cornea	It functions like a window that controls and focuses the entry of light into the eye.
Iris	It controls light levels inside the eye similar to the aperture on a camera.
Retina	It receives light that the lens has focused, convert the light into neural signals, and send these signals on to the brain for visual recognition.
Lens	It focuses light onto the retina and to help the eye focus on objects at various distances.
Pupil	It regulates the amount of light that enters the eye.
Rods	Photoreceptors in the retina of the eye, turning visible light into neuronal signals, which are sent to the brain.
Cones	Responsible for color vision and function best in relatively bright light, as opposed to rod cells, which work better in dim light.

Interesting Facts with Sight

The average blink lasts for about 1/10th of a second.
It only takes about 48 hours for the eye to repair a corneal scratch.
Sight requires about half of the brain to get involved.
Doctors have yet to find a way to transplant an eyeball. The optic nerve that connects the eye to the brain is too sensitive to reconstruct successfully.
You blink about 12 times every minute.
Even if no one in the past few generations of your family had blue or green eyes, these recessive traits can still appear in later generations.
Out of all the muscles in your body, the muscles that control your eyes are the most active.
80% of vision problems worldwide are avoidable or even curable.

Smell

The nose is a sense organ associated with smell,
it helps with detecting different smells,
and determines with the smell is good or bad

Section of the Brain, and Nerves

Olfactory bulb
The olfactory bulb is one of the structures of the limbic system and a very ancient part of the brain.
As mentioned in the previous description of the olfactory process,
the information captured by the sense of smell goes from the olfactory bulb to other structures of the limbic system.

Olfactory neuronOnce the neurons detect the molecules, they send messages to your brain, which identifies the smell.
There are more smells in the environment than there are receptors, and any given molecule may stimulate a combination of receptors,
creating a unique representation in the brain.These representations are registered by the brain as a particular smell.

Parts	Functions
Nasal Cavity	Serves to lighten the skull, to produce mucus, to warm and moisturize air breathed in.
Sinuses	It produces a mucus that moisturizes the inside of the nose.
Olfactory Bulb	Receives neural input about odours detected by cells in the nasal cavity.

Interesting Facts with Smell

People can detect at least one trillion distinct scents.
Scent cells are renewed every 30 to 60 days.
You can smell fear and disgust.
Smell is the oldest sense.
Women have a better sense of smell than men.
Age-related loss of smell is linked to race.
Dogs have nearly 44 times more scent cells than humans.
Loss of smell may signal future illnesses.
Each human has their own distinct odor.

Hearing

The ear is associated with hearing, it isn’t just the hearing organ. It is a complex system of parts that not only allows humans to hear, but also makes it possible for humans to walk.

Acoustic Nerve
known as the cochlear nerve -- acts as a busy highway, transmitting electrical data from the inner ear to the brain stem, where the signals are relayed to other parts of the brain.

Auditory Cortex
located in the temporal lobes of the brain, which are situated above the ears -- gives meaning to the large amount of information sent to it by the inner ear and cochlear nucleus. It is the language center of the brain and its role is to interpret sounds so they are understood.

Parts	Functions
Ex Auditory Meatus	the passage leading inward through the tympanic portion of the temporal bone, from the auricle to the tympanic membrane.
Tympanic Membrane Malleus	it is a thin membrane that separates the external ear from the middle ear.
Incus	receives vibrations from the malleus, to which it is connected laterally, and transmits these to the stapes, medially.
Stapes	transmits sound vibrations from the incus, another little bone in the middle ear, to the oval window adjacent to the inner ear.
Cochlea	It converts vibrations into neural messages.
Basilar Membrane	separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani.

Interesting Facts with Hearing

The smallest bones are the ossicles in the middle ear
The inner ear is no larger than a pencil eraser in circumference.
Your sense of hearing is dependent upon tiny hairs deep inside your ear. If you lose these hairs, you lose your hearing.
You do not need to clean wax out of your ears unless you have an abnormal condition. Ears push excess wax out as needed.
The majority of individuals suffering from hearing loss are under the age of 65.
The number one cause of hearing loss is exposure to excessively loud sounds (85 decibels or higher).
Your hearing can be damaged permanently even after a single incident of exposure to extremely loud noise (shotgun blast, explosion, etc.).
Your ears never stop hearing, even when you sleep. Your brain just ignores incoming sounds.
Your ears are more than just necessary for hearing; they also help you keep your balance.
Not all living creatures hear with ears. Snakes use jawbones, fish respond to pressure changes, and male mosquitoes use antennae.

Taste

The tongue is associated with the sense of tasteand allow you to experience tastes that are sweet, salty, sour, and bitter.

Parietal Lobe
either of the paired lobes of the brain at the top of the head, including areas concerned with the reception and correlation of sensory information.

Parts	Functions
Papillae	A small rounded protuberance on a part or organ of the body.
Taste Bud	Any of the clusters of bulbous nerve endings on the tongue and in the lining of the mouth that provide the sense of taste.
Region (Bitter)	Are way in the back.
Region (Sour)	Are behind salt taste buds.
Region (Salty)	Are on either side of the front of the tongue.
Region (Sweet)	Are on the tip of the tongue.
Region (Umami)	Was discovered later after basic roadmap of the tongue.

Interesting Facts with Taste

Everyone has a different number of taste buds.
You taste with your brain.
You can't taste well if you can't smell.
You can tweak your taste buds.
Sugar cravings have a biological basis

Touch

The skin is associated with the sense of touchThe primary function of the skin is to act as a barrier. The skin provides protection from: mechanical impacts and pressure, variations in temperature, micro-organisms, radiation and chemicals.

Touch receptors.
Touch receptors are a type of mechanoreceptor because they are activated by mechanical perturbation of the cell membrane.

Axon
located in either shallow or deep skin, and may be encapsulated by specialized membranes that amplify pressure. When the appropriate type of pressure is applied to the skin, these membranes pinch the axon, causing it to fire.

Parts	Functions
Mechanoreceptors	Are receptors in the skin and on other organs that detect sensations of touch.
Nociceptors	A sensory nerve cell that responds to damaging or potentially damaging stimuli by sending signals to the spinal cord and brain.
Thermoreceptors	Are specialized nerve cells that are able to detect differences in temperature.
Hair Follicle	Act as a sensitive touch receptor.
Papillary Muscle	Contract to prevent inversion or prolapse of these valves on systole.

Interesting Facts with Touch

The sense of touch is the first to develop in humans at about 8 weeks into the gestation period.
Touch stimulates the brain to release endorphins.
Blood pressure and heart rate can be reduced by a touch.
The skin is your body’s largest organ and contains more than 4 million sensory receptors.
Being touched can reduce stress, by lowering levels of hormones like cortisol.
Pain is the body’s warning system, and it’s thorough: People have more receptors for pain than for any other sensation.