Nervous SystemDouglas Todey

FunctionsIt has three main basic functions

Sensory neurons receive information from sensory receptors

Interneurons transfer and interpret impulsesMotor neurons send appropriate

impulses/instructions to the muscles and glands

Nervous SystemCentral Nervous System

It is responsible for all involuntary nerve actionThis is the brain and spinal cord

Peripheral Nervous SystemIt 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 ImpulsesThe 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 ImpulsesAt 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

potentialThe refractory period resets the balance. Ion pumps move Potassium back inside and Sodium back outside allowing the nerve to be ready for another stimulus

NeurotransmittersInformation is passed between neurons by

chemicals across the synapseNeurotransmitters 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 DiseaseIt 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 DiseaseThis 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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