The Human Body's Sensory and Response Systems

How the Human Body Perceives and Reacts

Humans constantly interact with their environment. This interaction is facilitated by complex relational functions.

These functions are carried out through three main types of components:

• Receivers
• Controllers
• Effectors

Receivers: Our Sensory Organs

Receivers are our sensory organs. They capture what happens outside or inside the body and send this information to the control center.

Controllers: The Nervous System

Controllers are the organs of the nervous system.

The Brain (Cerebrum)

Located within the cranium, the brain receives information from receptors, interprets and relates it, prepares response commands, stores information in memory, and coordinates all the body's organs.

The Spinal Cord

Situated within the spine, the spinal cord controls many bodily functions and prepares for fast and simple responses.

Nerves

Nerves connect the sensory organs with the spinal cord and the brain, and these central organs with the rest of the body.

Effectors: Executing Responses

Effectors are the body organs that carry out the ordered responses from the controllers.

Example: Locomotor muscles, which produce body movements when they receive commands from the brain and spinal cord.

The Advanced Human Relational System

Because our brain is especially developed, humans are the animals with the most complex and highly perfected relational functions.

Thanks to these functions, we are able to:

• Perceive and process information.
• Learn and adapt.
• Experience very deep feelings and a developed sensitivity.
• Express ourselves and communicate effectively.

Understanding Our Senses

Sight and the Eyes

The eyes are the receivers for the sense of sight.

• Light enters through the pupil.
• The lens focuses light and causes it to form an image on the retina.
• The retina converts the image into signals that it sends to the brain via the optic nerve.
• The brain interprets the signals from the retina and allows us to perceive the shape, color, distance, and movement of things.

Hearing, Balance, and the Ears

• The ears are the receivers for the sense of hearing.
• They capture vibrations that reach them.
• Vibrations enter through the ear canal to the eardrum.
• The eardrum vibrates and transmits this movement to the ossicles that lead to the cochlea.
• The cochlea transforms the vibrations into signals that it sends to the brain by the auditory nerve.
• The brain interprets these cochlear signals as sound.
• Another part of the ear is responsible for balance, sending signals to the brain about our body's position.

Taste and the Tongue's Papillae

• The papillae of the tongue are the receivers for taste. They are sensitive to substances that fall into the mouth and mix with saliva.
• For each substance, the taste buds produce different signals that they send via the gustatory nerve.
• The brain interprets these signals as different flavors.

Smell and the Olfactory Mucosa

• The olfactory mucosa inside the nose is the organ of smell. It is sensitive to substances that arrive by air.
• With each substance, the olfactory mucosa produces different signals that it sends via the olfactory nerve.
• The brain interprets these signals as different smells.

Touch and Skin Receptors

• The skin is the organ of touch. It contains many receptors sensitive to temperature, pressure, or contact.
• When these receptors detect something, they send signals through numerous nerve endings.
• The brain interprets these signals as cold, heat, pressure, or pain.

Test Your Knowledge

1. What do the eyes capture? Light and images.
2. What senses are associated with the ear? Hearing and balance.
3. What are flavors? Substances that enter through the mouth and mix with saliva.
4. How do substances that we smell reach us? By air.
5. Which body organ is responsible for sensing a prick on a finger? The skin, the organ of touch.