72 Our skin contains more than four million sensory receptors. It is our biggest organ! Exposure to sounds higher than 110 decibels, even for a short time, can cause instantaneous and permanent hearing loss. Do you know where the vestibular system is located? If you don t, search the web for information. THE SENSORY SYSTEMS The sensory systems receive and process information that generates an individual s awareness of the external environment. Broadly, sensations fall into three categories: exteroception, sensations from outside the body collected via the five senses of touch, sight, hearing, smell, and taste; proprioception, sensations about body position and movement. For example, it enables a person to close their eyes and touch the tip of their nose with a finger; interoception, sensations from inside the body, for example hunger, pain, and emotions. The exteroceptive system The exteroceptive system includes: broadly: in generale flavour: sapore savoury: saporito, gustoso taste bud: papilla gustativa to trigger: scatenare the tactile system, which processes touch information (like pressure, temperature, and pain) through receptors in the skin. It consists of two levels: the first informs the brain about where the touch is on the body, and the second says whether it is a safe or dangerous touch; the visual system, which is responsible for seeing; the auditory system, which is used to identify the quality and direction of sound , and is involved in understanding language; the olfactory system, which processes smell, and which is one of the oldest and most vital parts of our brain. It is closely linked to the gustatory system; 142 the gustatory system, which deals with flavours and allows us to discriminate between safe and harmful foods. Taste buds are small sensory organs located in the tongue responsible for experiencing tastes. There are five basic tastes: sweetness, when there is the presence of sugar; sourness, when there is some form of acidity; saltiness, when salt is present; bitterness, when it contains ingredients which may be perceived as unpleasant; umami, when the prevalent flavour is savoury. The proprioceptive system The proprioceptive system is very important for our body awareness because it lets us identify and control force and pressure. The proprioceptive receptors are located in our muscles, joints, ligaments, and even within our skin and bones. Movement triggers feedback from the receptors to our brain and these provide information about where our arms, legs, hands and feet are in relation to our body. This sense helps us to coordinate our movements, control the movement of the eyes and even some aspects of language development. The proprioceptive system includes the vestibular system , which contributes to balance and body orientation in space. The interoceptive system The interoceptive system collects the sensations related to the physical and physiological condition of the body, triggering responses that guide, for example, hunger, heart rate, and respiration. It is also linked to our emotional perceptions.