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Scot
psychology.docx1
Rods and cones are the only two types of photoreceptors found in human retina. Rods make vision at low light level possible a state called scotopic vision. They can’t mediate color vision and they are less accurate in detecting shape object. On the other hand cones are responsible for vision at higher light levels; they are concentrated in central fovea. There are 3 different types of Cone cells containing different pigments. Color blindness occurs when one or more types of cones are either totally absent, or has a limited spectral sensitivity
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Olfaction, our sense of smell, is very essential for our daily living. Live will me devastating without a smell of a nose. It helps us enjoy the flavors of our foods and to detect fragrance in air around us. A damaged olfaction could lead to a depression due to loose of joy of eating and drinking. Smell is very important because it give an ability to detect leaking gas or spoiled food.
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touch
The skin contains receptors for temperatures and touch. It’s also an excretory organ. Receptors are in different concentration at different parts of the body. There are high concentrations of temperature receptors at the elbow and few touch receptors at the heel of the foot. The fingertips and the sexual organs have the greatest concentration of nerve endings.
They are located at the taste buds of the tongue. Taste buds are located at the sides and top of the tongue. Some are found at the lining of the throat. There are four different taste receptors: sweet, sour, bitter and salt. Taste as a sense combines, smell, temperature and texture.
Sight
Seeing is the function of the eye. The key structures of the eye includes pupil which is the opening of the eye. Through this opening light enters the eye. The size varies with intensity of light. Iris determines the size of pupil. When pupil enlarges iris becomes smaller and when iris enlarges pupil become smaller. When there is brighter light pupil contract and in dim light it enlarges.
Hearing
Ear is the organ for hearing and balance. Ear detects vibrations, frequency and amplitude. These are impulses carried to the brain. The ear carry out the function of balancing by detecting direction of motion, acceleration and head position related to gravity.
Smell
Olfactory region in the upper region of nasal activity is responsible for smelling. 20 millions neurons that are concentrated in this area are the ones detecting odours. They are called olfactory neurons. The neurons send impulses to the brain when they detect gases. The responses produced by these stimuli can produce about 10,000 different smells. The receptors stop sending stimuli very quickly. That is why we get used to smells very easily.
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In order to see we need light. Light enters through the eye and are focused on retina. The light-sensitive photoreceptors of the retina initiate a cascade of electro-chemical signals that are transmitted to the brain. The visual system structures of the brain decode these signals, resulting in what we call "visual information." visual perception is a process that involves grouping, selection and interpretation.
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In the auditory system sound vibrations are converted in electrical energy by the hair cells. Vibration is received then causing air molecules to vibrate and in turn ear drum vibrating. Ear drum vibration cause ear bones to vibrate. These vibrations then pass in to the cochlea, the organ of hearing. Hair cells are then able to convert this movement (mechanical energy) into electrical signals (action potentials) which travel along auditory nerves to hearing centers in the brain. Mechanical sensory system use hair cells in acoustic, equilibrium and lateral-line systems to cause transduction process from cilia that respond to shearing forces and end with processes that depolarize the cell membrane of afferent neurons. Chemical sensory system is responsible for heromones species-specific odor cues.
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The damage of olfactory responsible for sense of smelling cause a lot of nervous changes. Food chemicals dissolved in saliva will not be able to stimulate taste receptors in taste buds. The nasal membranes will also fail to produce fluids that dissolve chemicals in air. These are chemicals that will have stimulated smell receptors in olfactory epithelium. The chemical senses complement each other and respond to many of the same stimuli.
