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 provides a highway for sensory input nerves coming in & up to the brain as well motor output nerves going down and out to muscles and glands 2. Peripheral NS: Nerves coming into and out from the spinal cord

Three Jobs of Nervous System 1. Receive sensory data: Sensory organs—eyes, ears, skin tongue, nose & send up to the brain 2. Brain processes this sensory data: Interpret, analyze and evaluate and make decisions 3. Motor Output: Brain send movement comments to our messages muscles and glands

What is the job of the: a) dendrites, b) soma, c) axon, d) myelin tissue, and terminal buttons?

Neurons transmit messages using chemical transmitters and electrical charges. 1. The dendrites of every neuron receive chemical neurotransmitters from thousands of surrounding neurons. 2. The messages are forwarded to the soma which processes the message and generates an electric charge. 3. This electric charge or neural impulse must move through the entire length of the axon to cause the terminal buttons to release neurotransmitters into the synapse.

The terminal buttons at the end of axons release neurotransmitters into the synapses

What is Crucial Nature of the Fatty Myelin Sheath?

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

The less myelin tissue surrounding the axon, the less likely neurons will relay messages as the electric charge won’t reach the terminal buttons to cause the release of neurotransmitters

What are neurotransmitters? Neurotransmitters are the chemicals released by axons into the synapse that transmit messages throughout the billions of neurons in our brain Some are agonists so increase neural activity: serotonin, noradrenalin, acetylcholine & dopamine Others are antagonists so decrease neural activity: GABA, adenosine,

1. The more neurons fire, the more dendrites they will sprout. The structure of neurons change the more they are exercised—and these changes make them more efficient 1. The more neurons fire, the more dendrites they will sprout. 2. The more dendrites a neuron has, the more neurons it is able to connect with, creating large neural networks 3. 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—resulting in many neural networks & a smarter brain

The myelin sheath also becomes thicker in highly active neurons The more neurons are exercised, the thicker the myelin tissue becomes. The thicker the myelin tissue, the faster the electric or neural impulse travels through the axon.

Neural plasticity is a miraculous process Plasticity refers to the brain’s ability to reorganizing itself according to need. The brains of blind people develop much larger auditory & parietal lobes than sighted people. Why? When a 3 year old girl, Jody, had her entire right hemisphere removed, her left hemisphere rewired its motor cortex to connect to muscles on both sides of her body. The brain’s ability to develop new neural connections occurs throughout life but requires more time and effort after our early years.

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

Nerve Centers in our Midbrain and Brain Stem work on an unconscious level: What is the function of each?

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

Our Cerebral Cortex is divided into two hemispheres connected by a bridge The corpus callosum and enables our hemispheres to keep in constant communication

Sometimes the corpus callosum is severed 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 both receive sensory data, process information and send out motor messages. But each has special jobs.

Functions of the Left Hemipshere Speaks and comprehends language Sees the parts of objects not the whole Is more rational and reasonable

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 Is more able to express and perceive emotions

Each Hemisphere has Four Lobes

Three Sensory Lobes Receive and Interpret data Occipital lobe receives and interprets visual data Temporal lobe receives and interprets auditory data Parietal lobe receives and interprets tactile data.

The Frontal Lobe analyzes, evaluates and makes decisions

Back of the frontal lobe has a strip of tissue called the motor cortex Back of the frontal lobe has a strip of tissue called the motor cortex. It moves our muscles

The front of parietal lobe has a strip that receives messages from surface of our skin. tactile data

Neurons transmit messages using chemical transmitters and electrical charges. 1. The dendrites of every neuron receive chemical neurotransmitters from thousands of surrounding neurons. 2. The messages are forwarded to the soma which processes the message and generates an electric charge. 3. This electric charge or neural impulse must move through the entire length of the axon to cause the terminal buttons to release neurotransmitters into the synapse.