Download Brain and Consciousness - Oakton Community College

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: LDopa 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
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