´╗┐SENSORY ORGANSThe physiological methods of perception. The organs are responsible for responding to outside stimulus. Content Summary:
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SMELL: The receptors responsible for smell (olfatory) are located in the olfactory epithelium. Basal cells generate new receptor cells every one or two months to replace the neurons damaged by exposure to the environment. Each bipolar sensory neuron has one dendrite that projects into the nasal cavity. Humans have about a thousand genes coding for olfactory receptors, but most of them are mutations that prevent them from being expressed. Processing information begins in the olfactory bulb which is located spherically called glomeruli. Your nose can remember 50,000 smells on average!
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TASTE: Taste (gustatory) is the ability to detect the flavor of substances such as food, certain minerals, and other various substances. An individual recieves taste through taste buds (Gustatory calyculi) which are concentrated in large numbers on the surface of the tongue. The sensation is categorized into five basic tastes: sweetness, sourness, saltiness, bitterness and umami. The full effect of taste and flavor can also be attributed to smell and texture. I think it's interesting how all of the senses are tied together. For your knowledge: After eating, your hearing isn't as sharp!
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HEAR:Hearing (auditory) is the ability to perceive sounds by detecting vibrations through the ear. The inability to hear is called deafness. In an individual, hearing is performed largely by the auditory system and is a chain of vibrations and reactions. Vibrations are detected and sent from the outer ear and funneled into your ear canal. When in the middle ear, it hits your eardrum and vibrates on the three smallest bones in your body: the hammer, anvil and stirrup. The stirrup then passes the vibrations to the cochlea, which are then sent to the brain to interpret via the auditory nerve. The brain then tells us what we are hearing!

APPLICATIONSensory perception is very important in the clinical/hospital setting and with my career. Any discrepancy with sensory perception can be a safety risk. I'm educated in ways to prevent this. Examples would be assisting an elderly patient with glaucoma or cataracts. The visually disabled need to be guided when walking, use special ophthalmic medications and need to be communicated with a little differently. It's important to tell a patient when you are leaving and introduce yourself when you enter the room. I also assist with the hearing impaired. Learning communication skills for these sort of patients is a crucial part of my career. It's important to maintain eye contact, keep my hands free of obstructions and let them see my facial expressions and hand gestures. With any patient that has impaired sensory perception, it's vital to establish the best source of communication to ease the patient's anxiety and promote the health/healing process.

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ESSENTIAL QUESTIONS
1. Use a flow chart to describe how sound waves in the air within the external auditory meatus are transduced into the movements of the basilar membrane (hair cells).

The basic pathway for hearing starts on the visible side of the head (the pinna). From there it goes the external auditory meatus to the the ear canal that leads to the eardrum (tympanic membrane). From the eardrum goes the malleus, incus, stapes, and then the oval window. The middle ear structures are delicate so the ear has evolved mechanisms to protect it. The tube leading from the external auditory meatus to the tympanic membrane is tortuous so that nothing poked into the meatus will hit the drum. The vestibular apparatus consists of the utricle and saccule and three semicircular canals. The base of each semicircular canal is expanded into an ampulla that contains sensory hair cells called cilia. From there, the cilia sends messages through the auditory nerve to the brain. The brain then interprets the sound and tells us what we are hearing. Sounds like a very long process, but it happens so quickly and continously.



´╗┐2. Describe how light is transmitted through the structures of the eye, refracted, and photoreceptors are stimulated to send the CNS to be interpreted. In other words, trace the path of light and the neural impulses sent to the brain.
First light enters the eye through the cornea and then passes through the lens. It passes it's way through different areas of the eye including aqueous and vitrous humor until it reaches the retina. Light is refracted by the cornea in such a way that it ends up as a focused image on the retina. These are converted to photoreceptors called either rods or cones. Rods function in dim light but they are not sensitive to color while the cones function best in bright light and are sensitive to color. These signals then travel from photoreceptors through two sets of adjoining cells that later form to become the body's optic nerve.


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