* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download The Nervous System - Marshall Middle
Neuroeconomics wikipedia , lookup
Synaptogenesis wikipedia , lookup
Neuroinformatics wikipedia , lookup
Brain morphometry wikipedia , lookup
Neurolinguistics wikipedia , lookup
Embodied language processing wikipedia , lookup
Human brain wikipedia , lookup
Aging brain wikipedia , lookup
Central pattern generator wikipedia , lookup
Haemodynamic response wikipedia , lookup
Activity-dependent plasticity wikipedia , lookup
Neurophilosophy wikipedia , lookup
Proprioception wikipedia , lookup
Optogenetics wikipedia , lookup
Development of the nervous system wikipedia , lookup
Selfish brain theory wikipedia , lookup
Synaptic gating wikipedia , lookup
Cognitive neuroscience wikipedia , lookup
Single-unit recording wikipedia , lookup
Embodied cognitive science wikipedia , lookup
Biochemistry of Alzheimer's disease wikipedia , lookup
Molecular neuroscience wikipedia , lookup
History of neuroimaging wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Neuroplasticity wikipedia , lookup
Neural engineering wikipedia , lookup
Microneurography wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Brain Rules wikipedia , lookup
Channelrhodopsin wikipedia , lookup
Neuroregeneration wikipedia , lookup
Neuropsychology wikipedia , lookup
Circumventricular organs wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Nervous system network models wikipedia , lookup
Metastability in the brain wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
(Students: Bolded, italicized, and underlined sections will be on the exam) The Nervous System: I. Function of the System: A. The nervous system controls and regulates the body’s activities. It is the body's information gatherer, storage center and control system. It can respond to stimuli, transmit nerve impulses, and activate muscles. It collects information about the external conditions in relation to the body's external state, analyzes this information, and initiates appropriate responses to satisfy certain needs. The most powerful of these needs is survival. B. Parts of the Nervous System: Nerves do not form one single system, but several which are interrelated. The two main systems of the nervous system are: 1. The Central Nervous System: The brain and spinal cord make up the central nervous system. 2. The Peripheral Nervous System: The peripheral nervous system is responsible for the body functions which are not under conscious control like the heartbeat or the digestive system. The smooth operation of the peripheral nervous system is achieved by dividing it into sympathetic and parasympathetic systems. These are opposing actions and check on each other to provide a balance. C. How the System Works: The nervous system uses electro-chemical impulses which travel along the length of the cells. The cell processes information from the sensory nerves and initiates an action within milliseconds. These impulses travel at up to 250 miles per hour, while other systems such as the endocrine may take many hours to respond with hormones. II. The Main Parts of the System: The Brain, Spinal Cord, and Nerves The main organs in the nervous system are the brain, spinal cord and nerves. The brain sends messages to the body, and the nerves make you feel things. A. Brain: The brain (ganglion) controls movement and processes information transmitted by the nerves. It controls some involuntary movement such as breathing and the beating of the heart. Other involuntary movements are not controlled by the brian, for example, the pulling your finger out of a fire. The brain also sends messages to the nerves which in turn, allow you to feel. The average adult brain is about three pounds, is pink-gray in color, and is divided into three main regions: 1. The Cerebrum: • is the largest part of the brain • receives and interprets this information from the senses, and is the center for rational thought and complex activities such as learning, memorizing, and reasoning • contains about 12 billion neurons • is separated into two halves by a deep groove • the right half of the cerebrum (right hemisphere) controls the left side of the body, and visa versa • the right side or hemisphere is responsible for creativity, emotions, art, and music • the left side (or hemisphere) is responsible for logical reasoning, analytical, and math skills 2. The Cerebellum: • lies below the cerebrum • is the center for most of your motor skills and balance • coordinates the voluntary muscles so that your actions are smooth and efficient (such as swimming, threading a needle, and threading a needle) 3. The Medulla: • is found at the base of the skull • controls the vital involuntary actions of the body (such as heart rate, breathing, muscular action of the digestive tract, swallowing, sneezing, and coughing) B. Spinal Cord: The spinal cord is a thick cord of neurons which allows all nerves to connect to the brain. It runs the length of your spine, through a tube formed by your vertebrae. Thirty-one pairs of nerves branch off the spinal cord. These nerves: 1. Transmit feelings and messages to the spinal cord which sends messages to the brain. 2. Controls actions that do not involve the brain (reflex actions) C. Nerves (or Neurons): Nerves interpret feelings from the body. They can sense movement sensations and give information to the spinal cord and brain. They also receive information from the brain which allows you to move your body. The main parts of a neuron are: 1. Soma (the main Cell Body): the main center, or core of the cell 2. Dendrite: a nerve fiber that carries messages toward the cell body. A neuron usually has several dendrites. 3. Axon: a nerve fiber that carries messages away from the cell body. There is only one axon for each neuron. Some axons are surrounded by a fatty covering called a myelin sheath that protects the axon and allows impulses to travel faster along the axon. 4. Synaptic Gap: Neurons do not touch each other, and between the axon of one cell, and dendrite of another cell is a gap called a synapse or synaptic gap. This gap is only about .005 millimeters wide. 5. Neurotransmitters: When an impulse reaches the end of an axon, the axon releases a chemical neurotransmitter into the synapse, which then carries the impulse to the dendrite of the next cell. The three types of neurons are: 1. Sensory Neurons: pick up stimuli and send the impulses produced by stimuli to the brain and spinal cord. Some of the stimuli picked up by sensory neurons include color, heat, noise, touch, and hunger. They are found in the skin, muscles, joints, internal organs, and sense organs. 2. Motor Neurons: transfer impulses from the spinal cord and brain to the muscles and glands. Motor neurons control voluntary actions such as walking, talking, or playing an instrument. They also control many involuntary actions, such as heartbeat, enzymes, and the movement of food through the digestive system. 3. Association Neurons: Association neurons relay impulses between sensory and motor neurons. They also relay impulses from sensory and motor neurons to the brain. They are found only inside the brain and spinal cord. III. Interaction with Other Systems: The nervous system interacts with every system, because it provides every system with information that allows it to move and function. Some examples of systems that directly interact with the system include: • The Skeletal System: The skeletal system protects the major parts of the nervous system (brain protected by the skull, and spinal cord surrounded by vertebrae). • The Integumentary System: Nerves use the skin to sense feelings. The skin is the main body organ which allows nerves to receive information from an outside environment. • Muscular System: The muscular system needs information from the nervous system to know what muscles to move. The nerves also tell the muscles to move away from things that can harm the body. IV. Some Diseases and Disorders: • Paralysis: Occurs when motor neurons are not able to activate the mucles of the body. Impulses from the brain to the muscles are cut off. Normally, paralysis is a result of the vertebra in the backbone being pushed on top of another, cutting or crusing the nerves in the nerve cord. As of now, no cure. • Tourette Syndrome: A syndrome that begins in childhood and manifests itself through tics. The tics include frequent, irregular movements of the head neck and shoulders. As the syndrome progresses these tics may also include snorting, sniffing, and involuntary vocalization. Meds may alleviate some of the symptoms, but there is no cure. • Parkinson’s Disease: Parkinson’s is diagnosed as slowing of the voluntary movements, muscular rigidity, and tremor at rest. These symptoms result from a reduction in neurons that make dopamine. Dopamine usually acts as an inhibitory neurotransmitter, which allows for full muscle control, without this it is impossible for patients to fully regain control. • Huntington Disease: Patients usually exhibits symptoms in the third or fourth decade of life. Those with huntington have a tendency to fidget which over months or years develops into jerky, uncontrolled movements. As the disease progresses it leads to dementia and usually death from infection. • Alzheimer Disease: Alzheimer Disease is the most common cause of dementia in western civilization. It affects more women than men, and lasts around five years. The disease often causes memory loss and the inability to fully function independently. There is no cure. • Meningitis: Meningitis is a caused by a bacteria or virus in which the protective membranes that surround the brain and spinal cord are attacked. Death can occur. Some of the major nerves in the body: