- Bring in info from the senses and internal organs - Assess, process, interpret, relay information - Output behaviour General Layout of the Nervous System 1. Central Nervous System - Brain - Spinal Cord 2. Peripheral Nervous System - Located outside of the skull and spine - Serves to bring information into the CNS and carry signals out of the CNS Somatic Nervous System
Interacts with external environment Bringing info in from the senses and carrying motor output to muscles o Afferent-- sensory to CNS o Efferent-- motor from CNS Autonomic Nervous System Controls the automatic functions of the body Afferent-- sensory from internal organs to CNS Efferent-- motor from CNS to internal organs: 2 kinds o Sympathetic Nervous System: fight or flight response, automatically accelerates heart rate, breathing, dilates pupils, slows down digestion o Parasympathetic Nervous System: automatically slows us down after a stressful event, heart rate and breathing slow down, pupils constrict and digestion speeds up Differences Between Parasympathetic and Sympathetic Nerves System - They generally have opposite effects Sympathetic: fight or flight Parasympathetic: rest and relaxation - All are two-stage neural paths Sympathetic: synapse close to spinal cord Parasympathetic: synapse far from spinal cord, close to target organ - Where they exit the spinal cord Sympathetic: thoracic and lumber Parasympathetic: cranial and sacral Cranial Nerves - Most nerves from PNS project from spinal cord but CN projects from brain - Numbered l-Xll, anterior to posterior - Most serve sensory and motor functions of head and neck (except X) - Because of functions and locations specific- can provide clues about tumours and other pathologies - Oh oh oh to touch and feel very good velvet ahhh heaven l- Olfactory nerve smell ll- Optic nerve vision lll- Oculomotor eye movements, control of pupil, lens and tears lV- Trochlear eye movements V- Trigeminal nerve facial sensations and chewing Vl- Abducens eye movements Vll- Facial facial movements, salivary glands, taste Vlll- Vestibulo- Cochlear nerve acoustic branch and vestibular branch IX- Glossopharyngeal throat muscles, salivary glands, taste
X- Vagus control and sensation of internal thoracic and abdominal viscera such as bronchioles, heart and stomach Xl- Spinal Accessory nerve head and neck muscles Xll- Hypoglossal tongue muscles Protecting the Brain 1. Protection from physical dangers - Skull - Meninges - Cerebrospinal fluid (CSF) 2. Protection from chemical dangers - Blood-brain barrier - Psychoactive drugs Meninges and CSF - CNS—covered by three meninges and encased in bone (skull or spinal cord) Dura Mater tough outer membrane Arachnoid Membrane weblike Pia Mater adheres to CNS surface - Cerebral Spinal Fluid Fluid serves as cushion Found in: Subarachnoid Space between arachnoid membrane and pia mater Ventricles
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- Fall '09