PSYC20008 Lecture Notes - Lecture 14: Enteric Nervous System, Peripheral Nervous System, Vagus Nerve
14 Jun 2018
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Lecture 14 - Thursday 13 April 2017
PSYC20006 - DEVELOPMENTAL PSYCHOLOGY
LECTURE 14
BRAIN DEVELOPMENT
ADULT HUMAN BRAIN
•Most complex system of which we know.
•Human brain and CNS consist of trillions of highly specialised cells that work in synchrony.
•Chemical signals
•Electrical signals
•Larger and more complex than brains of other mammals.
THE FIRST AND SECOND BRAINS
•Human brain makes up about 2/3 of the neuronal mass of the body and contains almost 3⁄4 of all
of our synapses.
•Enteric nervous system (gut) consists of sheaths of neurons embedded in the walls of the gut. The
gut is often called the second brain.
•It contains ~100 million neurons (more than the spinal cord or the peripheral NS).
•Brain outsources the digestion process to this nervous system.
•90% of fibers in the vagus nerve carry information from the gut to the brain.
•ENS uses more than 30 neurotransmitters.
•95% of the body’s serotonin is found in the bowels.
BRAIN GROWTH
•The brain grows at an astounding rate early in life;
•At birth, it weighs 25% of adult weight
•By age 2, it weights 75% of adult weight
•Between the 7th prenatal month and the 1st birthday, the brain increases in weight by ~1.7 grams
per day.
•“Brain growth spurt” - last 3 months prenatally and first 2 years after birth.
•There is a timetable, and cells have specific roles to play and places to be.
Lecture 14 - Thursday 13 April 2017
PSYC20006 - DEVELOPMENTAL PSYCHOLOGY
•Lots of brain disorders are related to faulty brain development prenatally or in the first few years
of life.
DEFINITIONS
•Central nervous system (CNS) is the brain and spinal cord
•Peripheral nervous system; Nerves attached to the CNS that lie outside of the CNS
•Soma; The cell body of a neuron, which contains the nucleus
•Dendrite; A branched, tree-like structure attached to the soma. It receives information from
terminals of other neurons
•Synapse; A junction between the terminal of the axon and the membrane of another neuron
•Axon; Long thin cylindrical structure that conveys information from the soma of a neuron to its
terminal.
•Multipolar neuron; A neuron with one axon and many dendrites attached to its soma
•Neurotransmitter; A chemical released by the nerve terminal that has an
excitatory or inhibitory effect on another neuron Source: Carlson (2010) chapter
NEURONS
•Basic unit of the brain
•Three basic types;
•Sensory neurons
•Motor neurons
•Interneurons
•All neurons have...
•1. Cell body - (soma), which contains all the information needed
to keep the cell functioning
•2. Dendrites - fibres that receive information from other cells and
conduct that information towards the cell body in the form of
electrical impulses
•3. Axon - the fibre, anyway from a few micrometers to over a
meter in length, that conducts electrical signals away from the cell
body to connections with other neurons
•Basic units of the brain and central nervous system (CNS).
•Receive and transmit neural impulses across the synapses.
•Product of the neural tube of the developing embryo.
Lecture 14 - Thursday 13 April 2017
PSYC20006 - DEVELOPMENTAL PSYCHOLOGY
•Neurons
migrate along
pathways laid
down by a
network of
guiding cells to
form the major
parts of the
brain.
•The vast
majority of
neurons a
person will
ever have has
already been
formed by the
end of the
second
trimester of
pregnancy.
•Scientists have
recently
established that
formations of
new neurons occur in the hippocampus (an area of the brain important for learning and memory)
and these new neurons occur throughout life.
•Neurons assume specialised
functions depending on where
they migrate.
•Any neuron has the potential to
serve any neural purpose
(pluripotency).
GLIAL CELLS
•Glial perform a variety of critical
functions.
•There are five key types of glial cells (diagram right above).
•Glial cells play a major role in communication within the brain by:
•Influencing the formation and strengthening of synapses.
•Producing myelin, that helps neurons conduct electrical messages along the neural network.
•Communicating among themselves in a network separate from the neural network.
•It is thought that people with schizophrenia or bipolar disorder may have a defect in a gene that
regulates the production of myelin.
ASTROCYTES
•Mop up excess neurotransmitters
•emitted from synapses
•Feed neurons by supplying nutrients and neurotransmitter
precursors
•Control where and when neurons will make new synapses !
OLIGODENDROCYTES
•Wraps tips around the axons of neurons and extrudes !
Document Summary
Adult human brain: most complex system of which we know, human brain and cns consist of trillions of highly specialised cells that work in synchrony, chemical signals, electrical signals, larger and more complex than brains of other mammals. Psyc20006 - developmental psychology: lots of brain disorders are related to faulty brain development prenatally or in the first few years of life. Neurons: basic unit of the brain, three basic types, sensory neurons, motor neurons, interneurons, all neurons have, 1. Cell body - (soma), which contains all the information needed to keep the cell functioning: 2. Dendrites - fibres that receive information from other cells and conduct that information towards the cell body in the form of electrical impulses: 3. Astrocytes: mop up excess neurotransmitters, emitted from synapses, feed neurons by supplying nutrients and neurotransmitter precursors, control where and when neurons will make new synapses. Oligodendrocytes: wraps tips around the axons of neurons and extrudes.
