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The Senses (Vision (Vision provides information about the environment and…
The Senses
Vision
Vision provides information about the environment and the objects in it - like sizes, shapes, textures, colors and distances.
How Vision Occurs: Light enters the eye through the pupil and reaches the lens, a flexible structure that focuses light on the retina. The retina contains two types of light-sensitive receptor cells, or photoreceptors: rods and cones. These cells are responsible for changing light energy into neuronal impulses, which then travel along the optic nerve to the brain, where they are routed to the occipital lobe.
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Binocular Fusion: The combination of the two images into one is called binocular fusion. Not only does the visual system receive two images but there is also a difference between the images on the retinas. This difference is called retinal disparity. It's essential for your depth perception.
Light: Is a form of electromagnetic radiation. Visible light represents a small portion of electromagnetic spectrum, which is composed of waves of different length and frequency.
Hearing
Hearing depends on vibrations of the air, called sound waves. Sound waves from the air pass through some bones of the ear until they reach tiny hair cells. These hair cells change souund vibrations into neuronal signals that travel through the auditory nerve to the brain. Loudness of sound is determined by the amplitude, or height, of sound waves. This strength, or sound pressure is measured in decibels. Pitch depends on sound-wave frequency, or the rate of the vibration of the medium through which the sound wave is transmitted.
Pathway Of Sound: Outer ear receives sound waves and the sound is directed to the auditory canal. The vibration causes the auditory canal to vibrate, which causes the eardrum to vibrate. Bones vibrate and push against the cochlea. The sound vibrations turn into neuronal impluses that are carried to the brain.
Deafness: Conduction deafness occurs when anything hinders physical motion through the outer or middle ear or when the bones of the middle ear become rigid and cannot carry sounds inward. Sensorineural deafness occurs from damage to the cochlea, the hair cells, or the auditory neurons.
Balance
The body’s sense of balance is regulated by the vestibular system inside the inner ear. Its prominent feature is the three semicircular canals. The stimuli for vestibular responses include movements such as spinning, falling, and tilting the body or head.
Smell and Taste
Are known as the chemical senses because there receptors are sensitive to chemical molecules rather than to light energy or sound waves. The molecules enter the nose and reach a pllace in which the smell receptors are located. These receptors send messages about smells through the olfactory nerve to the brain.
Much of what is referred to as taste is actually produced by the sense of smell. Sensations of warmth, cold, and pressure also affect taste. The combination of taste, smell and tactile sensations is known as flavor
Skin Senses
Receptors in the skin are responsible for providing the brain with at least 4 kinds of information about the environment: warmth, cold, pressure and pain. Sensitivity to pressure varies from place to place in the skin. Pressure sensations can serve as protection.
Perceptions of Pain: Pain results from many different stimuli. There are two types of pain sensations. The sharp, localized pain you may feel immediately after an injury and the dull, generalized pain you may feel later. According to the gate control theory of pain, we can lessen some pains by shifting our attention away from the pain impulses or by sending other signals to compete with pain signals.
The Body Senses
The sense of movement and body position is kinesthesis. It cooperates with the vestibular and visual senses to maintain posture and balance. Without kinesthesis sensations your movements would be uncoordinateed and jerky.
The sensation of kinesthesis comes from receptors in and near the muscles, tendons and joints. When any movement occurs, these receptors send messages to the brain.