external structure of the eyeball. The external layer of the eyeball is formed by the cornea‚ and the sclera. The cornea is a dome-shaped structure. The cornea does not have any blood vessels that is why it appears clear. The cornea does have nerves. The cornea is the first and most powerful lens in the eye’s optical system. The cornea is the first part of the eye to focus. When a ray of light hits the eye‚ the cornea is the first structure the light encounters. Then the light rays travel
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Introduction and Objective The action potential is an impulse of electrical activity. Action potential occurs when a neuron sends messages electrochemically down an axon called a nerve impulse. When a neuron is not stimulated or inactive‚ it is at resting potential. When a neuron is at rest‚ the electrical charge on the inside of the neuron is negative while the electrical charge on the outside of the neuron is positive. The resting membrane potential of a neuron is about -70 mV (mV = millivolts)
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nervous system is comprised of all nerves and nerve pathways that are outside the brain and spinal cord. Neuropathy can develop gradually or suddenly‚ and symptoms vary in severity among individuals. Peripheral Neuropathy can be broadly categorized by the 1) type of nerve that has been damaged‚ 2) location of nerve damage in the body or 3) disease process that causes it. In some cases‚ the cause cannot be identified. Types: There are three main types of peripheral nerves:
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The figure illustrates the parasympathetic division. What does "A" represent? cranial nerves The figure illustrates the parasympathetic division. What does "C" represent? terminal ganglia The figure illustrates the parasympathetic division. What does "E" represent? pelvic nerves parasympathetic effects more localized increases activity of GI tract effects are short-lived provides more extensive innervation of G.I. Tract craniosacral division functions at rest sympathetic effects are more general
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changes and feel sensations 2. Initiate responses to changes 3. Organize and store information Divisions 1. Central Nervous System – brain and spinal cord 2. Peripheral Nervous System – cranial nerves and spinal nerves (relays info to/from the CNS) - Autonomic Nervous System Nerve Tissue – neurons (nerve fibers) and specialized cells (Schwann‚ neuroglia) 1. Neuron cell body contains the nucleus; cell bodies are in the CNS or trunk; protected by bone 2. Axon carries impulses away from the cell
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Picking up a box from the floor and placing it on a shelf Light entering the eye forms an upside-down image on the retina. The retina transforms the light into nerve signals for the brain. The brain then turns the image right-side up and tells us what we are seeing. Our brain then computes to pick up the box. When a message comes into the brain from anywhere in the body‚ the brain tells the body how to react. the brain as a central computer that controls all bodily functions‚ then the nervous
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Transport of vesicles facilitated by kinesin and the effects of mutations in nerve transmission in Caenorhabditis elegans Introduction A nerve cell is made up of three main structures: the soma‚ the axon and the synapse. When a nerve cell receives a signal‚ a protein called kinesin travels anterograde along the axon and guides the synaptic vesicles until it reaches the synapse. This triggers the release of the neurotransmitters stored within the vesicles. Once released‚ the neurotransmitters then
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Figure 15.24b Structure of the ear. Oval window (deep to stapes) Entrance to mastoid antrum in the epitympanic recess Malleus (hammer) Incus Auditory (anvil) ossicles Stapes (stirrup) Tympanic membrane Semicircular canals Vestibule Vestibular nerve Cochlear nerve Cochlea Round window Middle and internal ear © 2013 Pearson Education‚ Inc. Pharyngotympanic (auditory) tube MIDDLE EAR STRUCTURES • Air-filled cavity in temporal bone • Auditory ossicles (outer to inner): – – – – – Malleus Incus Stapes
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Now‚ paste an image found on LabPaq site or Google images of a teased myelinated nerve and label its basic parts (nodes of Ranvier‚ neurilemma‚ the axon‚ Schwann cell nuclei and myelin sheath) using the labeling boxes provided. myelin sheath Schwann cell Nuclei Axon node of Ranvier neurilemma Questions A. What is the function of a neuron? B. What is the difference between a neuron and a nerve? C. What gives a multipolar neuron its name? D. What are the functions of the
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• Choroid - Middle layer of blood capillaries‚ which supply nutrients and oxygen. Its anterior dark screen with pupil is the iris. A convex lens is placed behind the iris. • Retina- The innermost layer on which‚ the image forms. The optic nerve starts from the retina. 3. The fluids filled in the chambers of eye ? • Aqueous humour – A watery fluid seen in the aqueous chamber [between cornea and lens] oozes from the blood. This fluid supplies nutrients and oxygen to cornea
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