The document describes the five senses and their respective receptors: mechanoreceptors, nocireceptors, chemoreceptors, photoreceptors, proprioceptors, and thermoreceptors. It elaborates on the sensory organs for touch, sight, hearing, smell, and taste, detailing their functions and anatomical structures, while also touching on conditions like deafness and taste disorders. Additionally, it explains how sensory information is relayed to the brain, highlighting the connection between smell and memory, and variations in taste sensitivity over a person's lifetime.

1. THE FIVE SENSES

2. 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 CO
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?
2

3. The SENSE OF TOUCH
It’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.

4. The SENSE OF SIGHT
http://www.youtube.com/watch?v=15P8q35vNHw&feature=player_detailpage&list=FLeuNPhk0_VLYR7

5. The SENSE OF HEARING
There are three parts to the ear:
the outer, the middle and the
inner.
The outer ear
Sounds 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.

6. The SENSE OF HEARING
The middle ear
Behind 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 ear
The 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

7. The SENSE OF HEARING
Deafness
Deaf 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

8. The SENSE OF SMELL
This 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.

9. 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

10. 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.

11. The SENSE OF TASTE
• 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.