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HAP Study Guide: Nervous System and Special Senses Test will be on Monday, April 2, 2012 Chap. 12: Neural Tissue 3 Functions (describe) o Sensory input: Input from special senses, internal receptors (hunger, thirst, etc) o Integration: Combining all available sensory input to make decision o Motor output: reacting to sensory input based on integration to create muscle or gland response. Organization Anatomical o CNS: Central Nervous System; includes brain and spinal cord. Integration center/decision maker o PNS: Peripheral Nervous System, includes all neurons not in CNS Responsible for sensory input and motor output Functional o Sensory: Collect information from special senses and internal temperature, hunger, thirst, blood sugar, blood pressure, etc sensors. o Motor: React to integration center command to illicit response through activation of skeletal muscle, smooth muscle, cardiac muscle, or gland response. Structure of Neurons o Cell body: Metabolic center of the cell; contains nucleus and organelles o Axon: Extension of cell body that transmits impulse AWAY from cell body o Dendrite: Extension of cell body that transmits impulse TOWARD cell body o Synapse: Gap between axon of one neuron and dendrite of next neuron Neurotransmitters: Chemical messenger released from axon terminal of one neuron to bridge the synapse and activate the dendrite of the next neuron o Structural classification: Multipolar: Most common in CNS; multiple dendrites and single axon Bipolar: Found in special senses of eyes; single dendrite and single axon Unipolar: Found in touch receptors; single extension with cell body pushed to side Anaxonic: multiple dendrites and single axon; cannot tell difference between dendrites and axon Neuroglia: Function to…… o Astrocytes: Most numerous; supports axons and holds neurons in place o Microglia: Phagocytic immune cells on CNS o Ependymal cells: Line ventricles (spaces in brain) to produce cerebrospinal fluid o Oligodendrocytes: Insulating cells of CNS o Schwann cells: Insulting cells outside of CNS Chap 14: Brain and Cranial Nerves Figure 14-1: Introduction to Brain Structures and Functions. Cerebrum o High-order thinking, processing, and sensory integration o Memory storage o Language processing and production Diencephalon o Thalamus Traffic cop/relay center o Hypothalamus Interacts with Endocrine System and hormone production Mesencephalon o Relay Center o Controls consciousness o Visual integration Pons o Relay center for sensory input o Visceral motor response Medulla Oblongata o Respiration and heart rate o Temperature control Cerebellum o Coordination of muscle movement Cranial Nerves (See table from notes) Chap. 15/16: Somatic/Autonomic Nervous System Somatic Nervous System: responsible for skeletal muscle response Autonomic Nervous System: responsible for smooth muscle, cardiac muscle, and gland response o Important for maintaining Homeostasis: maintaining a constant internal environment even though the external environment is constantly changing o Two “arms” of the ANS Sympathetic AKA Fight or Flight Response. Parasympathetic AKA Resting and Digesting. Chap 17: Special Senses/Vision Accessory Structures of the Eye o Conjuctiva: lining of inner eyelid and outer surface of cornea. Infection is called conjunctivitis or Pink Eye. o Lacrimal glands: Creates tears o Tears: products of lacrimal glands; contains enzymes that offer immune protection Layers of the Eye o Fibrous Tunic: Offers protection and support to the eye Cornea: Clear window on front of eye Sclera: White of the eye o Vascular Tunic: AKA Choroid Layer. Provides blood supply to the eye. Also contains: Iris = colored portion of eye Ciliary muscle = controls shape of lens o Neural (Sensory) Tunic: contains rods and cones, the photoreceptors that collect light to transmit to the brain through the optic nerve Fovea centralis is the pit of “perfect focus” Chambers of the Eye o Anterior chamber: between cornea and lens; contains the watery Aqueous Humor o Posterior chamber: located behind lens; contains the jelly-like Vitreous Humor Vision o What is the order of structures/substances that light passes through? 1. Cornea 2. Aqueous Humor 3. Lens 4. Vitreous Humor What is accommodation? The ability to focus light by changing the shape of the lens for far and near vision. The retina collects the light information in specialized photoreceptor cells called RODS and CONES. Axons carry the impulses received from each of these receptors cells and are bundled together on the posterior aspect of the eye. The leave the eye via the OPTIC NERVE. The fibers from the medial side of each eye cross over to the opposite side of the brain at the OPTIC CHAISM. This allows the visual fields to overlap, providing BINOCULAR VISION and DEPTH PERCEPTION. Emmetropia: perfect vision; 20/20 Hyperopia: Far-sighted; not common; glasses needed for reading not for far vision. Myopia: Near-sighted; most common reason to wear lenses; glasses needed for far vision. Presbyopia: Aging eyes; Lenses lose elasticity as aging happens requiring glasses for reading focus Hemianopia: “without half vision”; blindness on one side of visual field. Astigmatism: imperfection of cornea that scatters light as it enters the eye causing blurriness in one location. Glaucoma: Increase intraocular aqueous humor pressure; can damage retina and lead to blindness