THE FIVE SENSESTHE FIVE SENSES

RECEPTORS

Cells specialized in catching stimuli. We classify them according to the kind of stimulus

they are sensible to:– Mechanoreceptors: sensible to mechanical pressure or distortion. Example: Periodontal

ligament

– Nocireceptors: sensible to pain, either it’s external or internal. Example: Neurons in any area of the body.

– Chemoreceptors: sensible to chemical changes. Example: increase in concentration of CO2 in blood, our body respons by increasing the breathing.

– Photoreceptors: sensible to light, mainly located in the retina.

– Propireceptors: sensible to our position & the way our body is in the space.

– Thermoreceptors: sensible to absolute & relative changes in temperature. Example: skinny hair.

But,what stimulus do they detecte and where are they?

The SENSE OF TOUCHIt’s located all over the body. The less sensitive parts of the body are in the middle of the back and at the end of the elbow.

As you can see in the image the nocireceptors involved in this sense are in the upper layer of the skin, the epidermis.

The thermoreceptors are located in a underlayer of the skin, the Dermis. In the upper surface of the Dermis the mechanoreceptors related with a light pressure are located as long as the receptors sensible to an strong pressure are in a lower surface of the skin.

All of the receptors are connected to nerves that send signals to the brain and the spinal cord.

The SENSE OF SIGHT

http://www.youtube.com/watch?v=15P8q35vNHw&feature=player_detailpage&list=FLeuNPhk0_VLYR7xbCVGsdqQ

The SENSE OF HEARING

There are three parts to the ear: the outer, the middle and the inner.

The outer earSounds travel in waves through the air and into our ears. Inside the ears, the sound waves move along short tunnels which are about 25 millimetres long. There is wax in the tunnels which helps keep the ear clean. The sound waves reach a thin layer of skin called the eardrum and it vibrates.

The SENSE OF HEARINGThe middle earBehind the eardrum is the middle ear, where there are three tiny bones, the hammer, the anvil and the stirrup. These bones vibrate when the eardrum does. This makes liquid and hairs in the next part of the ear, the inner ear, move.

The inner earThe liquid and hairs are in a curled tube called the cochlea (pronounced cock-lee-uh).

Messages about the vibrations move along nerves to the brain. The brain tells you what the sound is. As well as hearing, the inner ear helps us keep our balance. The liquid in the inner ear swirls about when you move. Nerves in the inner ear tell your brain which way you are moving, and this helps you to keep your balance.

http://www.acoustics.salford.ac.uk/schools/lesson4/flash/earanatomy.swf

http://www.youtube.com/watch?v=ahCbGjasm_E&feature=related

http://www.acoustics.salford.ac.uk/schools/lesson4/flash/earanatomy.swfhttp://www.acoustics.salford.ac.uk/schools/lesson4/flash/earanatomy.swf

The SENSE OF HEARING

DeafnessDeaf people can't hear. A hearing aid can help them to hear. A bionic ear is a special hearing aid which is put inside the deaf person's head

DeafnessDeaf people can't hear. A hearing aid can help them to hear. A bionic ear is a special hearing aid which is put inside the deaf person's head

The SENSE OF SMELLThis is the sense more connected to memory because the odor particles go throw the nose, that acts like a filter for the air we breath, to the Limbic system of the Brain.

T

In the olfactory bulb is were the smells are recognized because each smell molecule fits into a nerve cell like a lock and key.

The SENSE OF SMELL

Humans have seven primary odors that help them determine objects.

ODOR EXAMPLE PICTURES

Camphoric Mothballs Picture

Musky Perfume/Aftershave Picture

Roses Floral Picture

Pepperminty Mint Gum Picture

Etheral Dry Cleaning Fluid Picture

Pungent Vinegar Picture

Putrid Rotten Eggs Picture

The SENSE OF TASTE

It can be defined as the ability to respond to dissolved molecules and ions called tastans.

The taste buds contain the receptor cells that send messages through sensory nerves to the brain. Taste buds can recognize five basic kinds of tastes: bitter, salty, sweet, umami and sour. The salty/sweet taste buds are located near the front of your tongue; the sour taste buds line the sides of your tongue; and the bitter taste buds are found at the very back of your tongue.

As you can see in the image, there are three morphologies of the taste buds located in different parts of the tongue.

• Everyone's tastes are different. In fact, our tastes change as we get older. During the childhood there are taste buds, not only on the tongue, but on the sides and roof of the mouth. This means we are very sensitive to different foods. Later, the taste buds began to disappear from the sides and roof of the mouth, leaving taste buds mostly on the tongue. When we get older, our taste buds will become even less sensitive, so we will be more likely to eat foods that we thought were too strong as a child.

• What if you could not taste anything? Things like medications, smoking, not getting enough of the right vitamins, injury to the head, brain tumors, chemical exposure, and the effects of radiation can cause taste disorders.

The SENSE OF TASTE