Douglas Todey

Functions It has three main basic functions Sensory neurons receive information from sensory receptors Interneurons transfer and interpret impulses Motor neurons send appropriate impulses/instructions to the muscles and glands

Nervous System Central Nervous System It is responsible for all involuntary nerve action This is the brain and spinal cord Peripheral Nervous System It is the system of nerves that are outside of the central nervous system This includes nerves running to the arms, hands, legs, and feet

Neuron

Simple Reflex Arc

Cerebral Hemispheres

Diencephalon

Brain Stem

Cerebellum

Nerve Impulses The membrane of the neuron is polarized with Na + on the outside and K + on the inside. This is its resting potential until a stimulus comes along When a stimulus comes along, the ion channels in the membrane open up and Na + rushes into the cell. It is now depolarized and is at its action potential. Polarization is removed and the threshold is reached where the ion channels open completely and all of the Na + flood into the cell allowing the stimulus to be passed on Now repolarizing occurs and the sodium ion channels close and the potassium ion channels open allowing K + to repolarize the electrical balance, albeit opposite

Nerve Impulses At this point, the membrane is hyperpolarized. There is more Potassium on the outside than Sodium on the inside. The membrane potential is slightly lower than the resting potential The refractory period resets the balance. Ion pumps move Potassium back inside and Sodium back outside allowing the nerve to be ready for another stimulus

Neurotransmitters Information is passed between neurons by chemicals across the synapse Neurotransmitters are released from one neuron at the presynaptic nerve terminal. They then cross the synapse and are accepted by the next neuron at a receptor Neurotransmitters are recognized only by specific receptors on the postsynaptic membrane. When it recognizes the neurotransmitter, it passes the message on in the same way to the next neuron

Alzheimer's Disease It is a kind of dementia where memory loss and loss of other intellectual abilities interfere with daily life Signs of Alzheimer’s include memory loss, difficulty with familiar tasks, confusion, problems with speaking or writing, decreased judgment, changes in mood and personality, and others 5.4 million Americans have Alzheimer’s There is no cure for Alzheimer’s but there are options to help with cognitive and behavioral symptoms

Parkinson's Disease This is a brain disorder in which dopamine is no longer produced by brain cells Main symptoms of Parkinson’s are shaking or tremor at rest, slowness of movement, stiffness, and trouble with balance There are approximately 1 million people in the US with Parkinson’s There is no cure, but therapy is targeted at controlling symptoms Treatment includes medication, surgical therapy, and general lifestyle modifications

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