Divisions of the Nervous System

Divisions Overview CCentral Nervous System PPeripheral Nervous System SSomatic AAutonomic Parasympathetic Sympathetic

Central Nervous System (CNS)  Central Nervous System  Consists of the Brain Spinal Cord  Both are covered/surrounded by  Three layers called meninges  Cerebrospinal fluid Shock absorber for the brain

Brain  Composed of 3 separate parts  Cerebrum (includes hypothalamus and thalamus)  Cerebellum  Brain Stem

Cerebrum  Largest and most prominent portion  Responsible for  Voluntary or conscious activities  Has 2 hemispheres  Right Controls left half of body Creativity and artistic ability  Left Controls right half of body Analytical and mathematical abilities

Cerebrum  Is made larger by folds and grooves on its surface  Grooves in the tissue divide it into 4 lobes Frontal: personality, reasoning Occipital: vision Parietal: sensory Temporal: speech, hearing

Cerebrum  Made of 2 layers  Cerebral cortex Processes information from senses Controls body movements Made of nerve cell bodies (called grey matter)  Inner layer Connects cortex and brain stem Made of axons with myelin (white matter)

Cerebellum SSecond largest region of the brain LLocated at the back of the skull CCoordinate your movements Posture, Balance, Agility

Brain Stem  Connects brain and spinal cord  Located beneath the cerebellum  3 major areas  Pons Regulates breathing, passes signals between brain and spinal cord  Midbrain Reflexes  Medulla Oblongata Connects brain to spinal cord Heart function, vomiting, swallowing, coughing

Thalamus and Hypothalamus  Found between brain stem and cerebrum  Thalamus Sorts info from sensory organs and passes signals between the spinal cord and other parts of the brain  Hypothalamus Controls and recognizes Temperature Thirst Hunger

Spinal Cord  Acts as a communication link between the brain and rest of body  uses 31 pairs of nerves that branch  Certain types of info are only processed in the spinal cord  Reflexes Quick response to stimulus

Reflexes  Quick response to a stimuli  Sneezing  Blinking  Gag  Signal does not have to travel from spinal cord to brain  Called Reflex arcs

Peripheral Nervous System  Consists of all nerves and associated cells not in the brain or spinal cord  Split into two pieces Sensory Motor Also divided into two more regions Autonomic Nervous System Somatic nervous system

Somatic Nervous System  Mainly regulates activities that are under conscious control  Ex: Moving of arms or legs

Autonomic Nervous System  Regulates body processes that are under unconscious control  Controls Heart rate Breathing Blood flow Sweat glands Digestion

Autonomic Nervous System  Split into two parts  The two parts oppose one another  Sympathetic nervous system  Parasympathetic nervous system

Sympathetic Nervous System IInitiates flight or fight mode SSpeeds up heart rate and blood flow SSlows digestion PProduces more adrenaline CControls wakefulness PPupils dilate

Parasympathetic Nervous System  Does opposite of sympathetic – controls “relaxation”  Decreases heart rate and blood flow  Brings digestion back to normal  Constricts pupils  Lowers adrenaline output

Review  Parts and functions of the Nervous system  Central  Peripheral Somatic Autonomic Sympathetic Parasympathetic

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