They receive the information from the outside.
We use the eyes that detect shape, colour and location:
Pupil: small hole so light enters
Cornea: a transparent layers of cells to protect the pupil
Lens: They project the image upside down in the retina.
Retina: It has optic cells that detect light and colours and send information to the optic nerve
Optic nerve: send the information to the brain that turns the image the right way again
To smell things with the nose. We detect thousands of smells.
The air particles go to the nasal cavity
The olfactory cells detect the information and send it to the olfactory nerve
The olfactory nerve transmit the information to the brain
To taste things with the tongue.
Taste buds (papilas gustativas) are tiny bumps (bultos) in the tongue that detect the flavours. They send the information to the gustatory nerves and to the brain.
To hear with your ears and to keep balance. Ears have 3 parts:
1. Outer ear: It has the pinna (oreja-the ear we see) and the ear canal (canal auditivo).
2. Middle ear: It has the eardrum (tímpano-a membrane that vibrates with the sound).There are 3 small bones (hammer, anvil (yunque) and stirrup (estribo)) that move and transmit the vibrations.
3. Inner ear: It has the cochlea (cóclea o caracol) that detects the vibrations and send them to the auditory nerve to the brain. It also has the semicircular canals (conductos semicirculares) to help you keep balance.
To touch and feel things with your skin. The skin detects pressure, temperature and textures and also feel pain. It has 2 layers: epidermis and dermis
dermis: there are nerves in the dermis that send the information to the brain