Download Mod 07-Lecture - Phoenix Military Academy

Module 7: Neural & Hormone systems
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What is “biological psychology”?
“Biological psychology” = studies links between biology and behavior and mental
processes. Its central tenet is that everything psychological is simultaneously biological. We
think, feel and act through the physiology of our body. Our biology enables and limits our
ability to behave, think and feel
*Biological psychology = neuropsychology , biopsychology, behavioral genetics,
physiological psychology, behavioral neuroscience
BP focuses particularly on the nervous and endocrine systems which enable
communication and information processing within our bodies.

What is a neuron?
Our nervous system is an electrochemical communication system.
Neurons = nerve cells, the building blocks of our neural information system.
Soma or cyton or cell body = cell body of the neuron, the nucleus or brain of the cell
Dendrites = bushy fibers that receive neural information
Axon = the elongated-tail ending in branchlike axon terminals that transmit info. Axons
can be very short or very long, projecting several feet throughout the body.
Axon terminals or terminal buttons or synaptic knobs = endpoint of a neuron where
neurotransmitters are stored
Myelin sheath = fatty tissue insulating some axons that help speed up neural impulses.
Transmission rates range from a sluggish 2 miles an hour to the occasional 200 miles an hour
(MS). But even their top speed is 3 million times slower than electricity (which is why human
reaction time is measured in milliseconds and a computer’s RT measured in nanoseconds).
Nodes of Ranvier = indents in the myelin sheath. Saltatory conduction = speeded up
neurotransmission due to myelin sheath/nodes of Ranvier.
Glial cells = guide growth of developing neurons, providing nutrition and removing
waste, and producing myelin sheathes.

What are the firing phases of a neuron?
A neuron has three firing phases:
Action potential = when a neuron fires an impulse, it’s in effect a brief electrical charge
that travels down the axon. It is real electricity, capable of lighting up a light-bulb (if coupled
with another handful of neurons).
Refractory period = the “recharging phase” when a neuron after firing cannot
immediately generate another action potential.
Resting potential = state where neuron is at rest and capable of generating an action
potential.
Threshold = level of stimulation (excitement less inhibition) required to trigger a neural
impulse (party animal/party pooper analogy).
All-or-nothing principle = if a neuron fires, it always fires at the same intensity; thus all
action potentials are the same strength. All neural communication is based neurons which either
fire; or don’t.
The neural firing process has to do with waves of depolarization (excitatory) and
repolarization (inhibitory or perhaps more accurately when the neuron is returning to normal
balance after firing) that has to do with the changing positive/negative charge of potassium and
sodium ions in and outside of the neuron. During the resting phase there is more negative ions
inside the cell than outside. I’m assuming that the reverse is true for the action potential phase.
Presynaptic and postsynaptic neurons seem to refer to the sending and receiving neurons
The toilet is a good analogy for neural firings (p. 124)
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What are neurotransmitters?
Synapse = minute fluid-filled gap between dendrites and axons (less than a millionth of
an inch wide) called the “synaptic gap or cleft”; axons & dendrites don’t actually touch each
other.
(Synaptic) vesicles = house specific neurotransmitters
Neurotransmitters = chemical messengers sent from the vesicle sacs of the axon through
the synaptic gap and bind to receptor sites in the dendrites of the receiving neuron, influencing
its action potential.
The sending neuron then reabsorbs excess NT molecules in a process called reuptake.
NTs will only fit into particular receptor sites, like keys that only fit certain locks.
NTs have either an excitatory effect, making it more likely the receiving neuron will fire;
or an inhibitory effect, making it less likely.
Particular NTs seem to effect particular behavior and emotions.
Dopamine = affects learning, attention and emotion (alertness and movement); excess D
activity is linked to schizophrenia while a lack is linked to Parkinson’s disease. Dopamine
antagonists help with SZ symptoms.
Serotonin = affects hunger, sleep, arousal and mood; low S levels to depression; and high
levels to mania; Prozac and other anti-depressants are serotonin agonists.
GABA (gamma-aminobutyric acid) = inhibits firing of neurons; a lack of GABA is
associated with anxiety disorders and Huntington’s disease. Malfunctioning GABA system is
associated with seizures
Endorphins = (literally “morphine within”) are a natural, opiate-like NTs linked to pain
control and pleasure. Runner’s high is the result of endorphins.
Acetylcholine or ACh = triggers muscle contraction and affects learning and memory.
Lack of Ach is associated with Alzheimer’s disease.
Mood altering drugs (and some diseases and foods) affect communication at the synaptic
gap, either by exciting or inhibiting neuron firing.
Agonists = similar enough in chemical structure to particular NTs to bind to receiving
synapse and excite the neuron into firing (a/o blocking its reuptake). Ex: black widow venom
that mimics Acetylcholine causing uncontrollable convulsions.
Antagonists = chemically similar enough to bind to the receiving synapse, but not similar
enough to signal a firing, thus effectively blocking NT action. Ex: South American curare
poison which inhibits Acetylcholine firing causing paralysis.

What are the steps of the neural chain?
There are three types of neurons/nerves:
Sensory or afferent neurons = carry info from our tissue and sensory receptors (input) to
the brain. (Receptor cells = specialized cells in the sensory system, i.e., sight, hearing, taste, etc.,
that can turn other kinds of energy into action potentials that the NS can process.)
Inter-neurons = the CNS’s own neurons (brain & spinal cord) responsible for processing
sensory input and motor output
Motor or efferent neurons = sends info back from the CNS to the muscles & glands
(output). Muscle and gland cells are called effectors.
We have a few million SN, a few million MN, but billions and billions of IN.
Reflexes = simple, automatic, inborn response to a sensory stimulus, i.e., a knee-jerk
response, sneezing blinking. Reflexes sometimes bypass the brain altogether, sensory input to
the spinal chord results in muscular directives directly from the spinal cord, which is why we
sometimes feel we react to things (an unexpectedly hot thing) before our brain’s even registered
what’s happened.
Reflex arc = path over which the reflex arc, typically involving just a few neurons
So people with severed spinal cords (i.e., Christopher Reeve) don’t feel pain or pleasure
in their body, but still have reflexes.

What are the various nervous subsystems
Our nervous system is composed of the central nervous system and the peripheral
nervous system.
o Central NS = the brain and spinal chord which process information; they’re so
important they’re both encased in bone. Spinal cord is protected by meninges
(membranes) and is composed of interneurons and glial cells which produce
cerebrospinal fluid. Brain is also protected by meninges.
o Peripheral NS = the nerves that link the CNS to the body’s sense receptors,
muscles and glands, i.e., all sensory & motor neurons. Nerves are made up of
axons bundled into “electrical cables”.
The Peripheral NS has two components:
o Somatic or skeletal NS = controls the movements of our skeletal muscles, i.e., all
voluntary functions
o Autonomic NS = controls the glands and muscles of our internal organs, i.e., all
involuntary functions like heart, lungs and digestion. The ANS is called
autonomic because it is self-regulating, i.e., operates without any conscious effort
or awareness.
The ANS is a dual system made up of:
o Sympathetic NS = kicks in times of perceived threat. This is our fight or flight
response, i.e., raised heartbeat, raised blood sugar, artery dilation, perspiration,
inhibited digestion, dilated pupils, relaxed bladder, inhibition of tear ducts, release
of adrenalin. The SNS arouses and expends energy.
o Parasympathetic NS = kicks in when the stress/crisis has passed our, conserving
energy and calming us down, reversing the above physiological reactions.

What is the endocrine system?
Endocrine system = called the body’s slower informational system because it works
through glands secreting hormones into the blood stream. Hormones are chemically similar to
NTs(meaning they also chemically lock onto receptor sites), but glandular secretion takes much
longer (seconds) to transmit (and reverse) directives.
Pituitary gland = called the master gland because it influences all the other glands; it’s
the size of pea & located at the base of the brain, connected to and controlled by the
hypothalamus. The pituitary also influences growth and pregnancy.
Thyroid = located in the neck and it regulates metabolism & energy level
Adrenals = located atop our kidneys, they release epinephrine & norepinephrine as part of
our fight or flight response
Sex glands = testis & ovaries release hormones testosterone (primarily male) & estrogen
(primarily female) which influence emotion and physical development. Men and women have
both hormones, but in different proportions
Pancreas = also near the kidneys, regulates blood sugar
Parathyroid = also in the neck, regulates the calcium in the blood
Pineal = produces melatonin which regulates circadian rhythms (alertness and arousal)
Hypothalamus = produces hormones that excite or inhibit pituitary