Nervous System Aids in response (reaction) to an outside force (stimulus) Critical for survival Involves the 5 senses Function: sends messages  How does the Nervous System compare to the Endocrine System?

Neuron: Nerve cell (specialized)/ Most in brain and spinal cord Little regeneration Axon (long arm)  Covered by myelin (fat)  Carry messages AWAY to the dendrites of the next neuron Dendrites (short arms)  Pick up messages from the axon of the other neuron Synapse (space between neurons) Neurotransmitters released  Acetylcholine  Dopamine  Cholinesterase shuts off acetylcholine

Transmission of a Message: Polarized Nerve (resting potential):  Na+ outside K + inside Depolarized Nerve (action potential):  Na+ moves inside K + moves outside  Imbalance of ions and acetylcholine released into synapse  Contraction of muscle Repolarized Nerve:  Action terminated

Nerve: a bunch of neurons Nerves send messages to muscles to move Multiple Sclerosis:  An autoimmune disease  Myelin eaten away  WBC and T cells attack myelin  Progressive disease  Symptoms include: tingling, paralysis, loss of equilibrium, blurry vision, headaches, muscle spasms, numbness  No cure  Connection to chicken pox virus?

Myasthenia Gravis:  Low amount of acetylcholine produced at neuromuscular junction  Symptoms: weak, tired, facial muscles fatigued Poison Gas (Curare):  WW 2 stockpiles of nerve gas  Interfered with production of cholinesterase  Acetylcholine would continue to be released at the neuromuscular junction  Diaphragm with muscle spasms  Resulting death

Action Pathway: Sensory Neuron (in sense organ): carries message to -- Association Neuron (in brain or spinal cord) -- connects to -- Motor Neuron (in muscle or gland) to carry out action Reflex Action:  Involuntary, rapid, no brain involvement

Central Nervous System Includes brain and spinal cord “Command Centers” Interpret incoming information and issue instructions Brain: (3 lbs.)  Cerebrum:  Consist of 2 hemispheres  Grooves called sulci  Ridges called gyri  Conscious thought, learning, emotional response, higher intellectual reasoning  Broca’s Area (speech)  Corpus Callosum: connects right and left hemispheres

 White Matter  Gray Matter  Parkinson’s Disease: tremors, problems with muscular movement, lack of dopamine (neurotransmitter)  Thalmus:  Relay station  Crude recognition of whether a sensation is pleasant or unpleasant  Hypothalmus:  Controls body temperature, H 2 O balance, metabolism, emotions, drives  Influence on pituitary gland and pineal gland  Limbic System (thirst, appetite, pain, pleasure center

 Medulla Oblongata:  Part of the brain stem  Connects with the spinal cord  Controls blood pressure, breathing, swallowing, vomiting  Cerebellum:  Controls balance and equilibrium  Controls body movements

Protection of the CNS: Meninges:  Covering over brain tissue/spinal cord  Meningitis: infection of meninges  Encephalitis: brain swelling Cerebrospinal Fluid (CSF):  Fluid in brain and spinal cord  Acts as cushion Blood Brain Barrier:  Composed of capillaries  Prevents certain substances from entering brain tissue  Glucose, essential amino acids, H 2 O cross barrier

Brain Abnormalities: Concussion: Bruised brain; dizzy Contusion: brain tissue damaged CVA (stroke): 3 rd leading cause of death in the U.S. TIA: (5-50 min.); temporary numbness, impaired speech; a “warning” Alzheimer’s Disease: progressive degeneration of the brain; protein deposits; no cure; cause unknown; possibly genetic

Spinal Cord (17” long)  Enclosed in the vertebrae  Covered by meninges and contain CSF  Involved with reflexes Peripheral Nervous System (outside CNS) Somatic Nervous System (Controls skeletal muscles) voluntary Autonomic Nervous System (Controls smooth and cardiac muscles) involuntary  Sympathetic Nervous System (for physical activity/stress)  Parasympathetic Nervous System (helps to “unwind”)