Function of Nervous System CENTRAL AND PERIPHERAL NERVOUS SYSTEMS

Central vs. Peripheral Nervous Systems 1. Central NS: Brain and spinal cord Brain evaluates and analyzes the incoming data and decides how to respond Spinal cord contains bundles of the axons sensory input neurons and motor output neurons 2. Peripheral NS: Nerves coming into and out from the spinal cord

Three Jobs of the Nervous System 1. Receive sensory data: Five senses send sensory information to brain 2. Process sensory data: Interpret, analyze and evaluate 3. Motor Output: Send messages out to muscles and glands to react/respond

Three Types of Neurons Sensory Neurons: Neurons in our five senses that receive sensory data and send it up through our spinal cord to our sensory lobes Processing Neurons: Neurons in our conscious and unconscious brain that interpret, evaluate & analyze the sensory data Motor Neurons: Neurons that extend from our brain through our spinal cord to move muscles and glands

How Neurons Transmit Messages 1. Neurotransmitters are received by the receptor sites of the dendrites and sent to the soma 2. Soma processes the message and generates an electric charge 3. The electric charge runs through the axon to the terminal buttons where neurotransmitters are released into the synapse

The terminal buttons at the end of the axon release the stored neurotransmitters into the synapse

Neurons change in structure if they are exercised extensively The more neurons fire, the more dendrites they will sprout. The more dendrites a neuron has, the more neurons it is able to connect with. Neurons that have many connections with other neurons create large neural networks and smarter brains.

Learning occurs as a result of our brain creating trillions of new interconnections

The myelin sheath changes in highly active neurons The more neurons are exercised, the thicker the myelin tissue becomes. The thicker the myelin tissue, the faster the electric impulse can travel through the axon, up to 200 miles per hour.

Neural plasticity is a miraculous process Brains are constantly reorganizing dependent upon the demands being made. Neuroplasticity is optimal during our early years. Brains exposed to enriched and challenging environments become smarter due to the growth of new extensive neural networks. Neuroplasticity or the ability to establish new neural networks occurs throughout life but does require more time and effort during adulthood.

If the myelin tissue begins to die, people develop multiple sclerosis

Symptoms of Multiple Sclerosis With the loss of myelin tissue, the electric charges no longer are able to reach the end the axon’s terminal buttons in an efficient manner. Therefore, the axon will no longer release neurotransmitters to surrounding neurons. The neurons in the peripheral nervous system are the major target. So motor output and sensory input messages are not being handled in an efficient fashion.

Parkinson’s is the result of the mid brain producing too little dopamine

Parkinson’s is treated through chemistry & electricity: L-Dopa and electrodes implanted in the mid-brain reduce the tremors.

How Diagnose Disorders: Brain Imaging to show structure & activity level CT (CAT) Scans: x-rays of the brain MRI & fMRI: radio waves bounce off the magnetic field of our brain PET Scans: measure amount of glucose being metabolized in different areas of the brain EEG: measure electric charges coming from surface of the brain

Electroencephalographs measure level of electrical activity via electrodes

Nerve Centers in our Midbrain and Brain Stem work on an unconscious level

The growth of new neurons, called neurogenesis, only occurs in the hippocampus

The largest proportion of our brain is composed of thick top layer: Cerebrum Proportionately, our brain has more cerebral tissue than any other animal

Our Cerebral Cortex is divided into two hemispheres connected by a bridge The bridge that allows our hemispheres to keep in constant communication is the:

Sometimes sever corpus callosum to stop epileptic seizures Severing the bridge that connects the hemispheres, stops the epileptic electrical storms from spreading throughout the brain

Left and right cerebral hemispheres have many similar functions but also each has specializations

Functions of the Left Hemipshere Speaks and comprehends language Sees the parts of objects but not the whole Is more rational and reasonable Tends toward being critical and judgmental

Two Language Centers in Left Hemisphere

Functions of Right Hemisphere Processes and produce music Has visual-spatial skills so can recognize objects and faces in three dimensional space: sees the whole Is more able to express and perceive emotions Is far more free-spirited and “in the moment.”

Each Hemisphere has Four Lobes

Receive andInterpret Three Sensory Lobes: Each Receive and Interpret sensory data Receive and interpret visual, tactile and auditory inputs

The colored areas receive the various types of sensory input data while remaining areas of each sensory lobe interprets this data

The Prefrontal Lobe Sees the Big Picture Evaluates, analyzes, problem-solves and decides how to respond to incoming information

Back of the Frontal lobe contains the Motor Cortex

Motor Cortex in Frontal lobe is right in front of somatosensory cortex in the parietal lobe