Unit 3A notes pp. 51-65, Neural processing and the endocrine system
Updated for 2011
(goes with Neuroscience and Behavior in 2007 book)
I. History of Mind pp. 51
Ancient Conceptions about Mind
Plato correctly placed mind in the brain.
His student Aristotle believed that mind was in the heart.
Today we believe mind and brain are faces of the same coin. Everything that is psychological is
simultaneously biological.
Franz Gall: Known for his advocacy of Phrenology
In 1800, Gall suggested that bumps of the skull represented mental abilities. His theory, though
incorrect, nevertheless proposed that different mental abilities were modular.
Biological Psychology
– branch of psychology concerned with the links between biology and behavior
– some biological psychologists call themselves behavioral neuroscientists,
neuropsychologists, behavior geneticists, physiological psychologist, or
biopsychologists
II. Neural Communication, pp. 52
What are neurons and how do they transmit information?
“C DAT”: path of an impulse- dendrites, axon, terminal buttons
Neuron: a nerve cell, the basic building block of the nervous system
Order of a transmission: dendrite, cell body, axon, synapse (see arrows)
Cell Body: Life support center of the neuron.
Dendrites: Branching extensions at the cell body. Receive messages from other neurons.
Terminal Branches of axon: Branched endings of an axon that transmit messages to other
neurons.
Axon the extension of a neuron, ending in branching terminal fibers, through which messages
are sent to other neurons or to muscles or glands
Myelin [MY-uh-lin] Sheath
A layer of fatty cells segmentally encasing the fibers of many neurons
Makes possible vastly greater transmission speed of neutral impulses; damage to can lead to
Myelin Sheath: outer coating that protects the axon of a neuron. A sheath protects a sword.
Multiple sclerosis
Action Potential a neural impulse; a brief electrical charge that travels down an axon;
Works like flushing a toilet: All or none—the toilet either flushes or it doesn’t; refractory period--tank must fill before toilet can be flushed again.
DEPOLARIZED
Generated by the movement of positively charges atoms in and out of channels in the axon’s
membrane
Depolarization: occurs when positive ions enter the neuron, making it more prone to firing an
action potential.
Hyperpolarization occurs when negative ions enter the neuron, making it less prone to firing an
action potential.
Oligodendroglia: CNS cells that produce myelin
Schwann Cells: PNS cells that produce myelin and help axons regenerate
Astrocytes: absorb dead neural cells
1. Sodium ions flow in, potassium ions flow out; both are positively charged
2. As this occurs down the axon membrane, an action potential is said to be at work.
Memory tip: think of a potato chip: potato or potassium is on the inside; salt or sodium in on
the outside; and negative charge inside (the wine); positive charge outside (the water)
Excitatory: signals that accelerate neuronal communication
Inhibitory: signals that slow down communication
Threshold the level of stimulation required to trigger a neural impulse
Each neuron receives depolarizing and hyperpolarizing currents from many neurons. When the
depolarizing current (positive ions) minus the hyperpolarizing current (negative ions) exceed
minimum intensity (threshold) the neuron fires an action potential.
Refractory Period: After a neuron fires an action potential it pauses for a short period to recharge
itself to fire again.
Sodium-Potassium Pumps: Sodium-potassium pumps pump positive ions out from the inside of
the neuron, making them ready for another action potential.
All-or-None Response: When the depolarizing current exceeds the threshold, a neuron will fire.
If the depolarizing current fails to exceed the threshold, a neuron will not fire.
Intensity of an action potential remains the same throughout the length of the axon.
The body’s information system is built from billions of interconnected cells called neurons.
We are a biopsychosocial system.
Neurobiologists and other investigators understand that humans and animals operate similarly
when processing information.
How Neurons Communicate
How do nerve cells communicate with other nerve cells? 55
Synapse [SIN-aps] junction between the axon tip of the sending neuron and the dendrite or cell
body of the receiving neuron
Tiny gap at this junction is called the synaptic gap or cleft
Neurotransmitters, p. 55
Chemical messengers that traverse the synaptic gaps between neurons
when released by the sending neuron, neuro-transmitters travel across the synapse and bind to
receptor sites on the receiving neuron, thereby influencing whether it will generate a neural
impulse
How do neurotransmitters influence behavior and how do drugs and other chemicals affect
neurotransmission?
Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of
reuptake. This process applies the brakes on neurotransmitter action.
Ach is at every junction between a motor neuron and skeletal muscle. When it’s released the
muscle contracts.
Endorphins [en-DOR-fins]
“morphine within”
natural, opiatelike neurotransmitters
linked to pain control and to pleasure
Origins of some neurotransmitters
Ach
CNS, PNS, ANS
Serotonin CNS, PNS (Serotonin is similar to Ecstacy and LSD)
GABA
CNS
Dopamine CNS (Dopamine is similar to cocaine)
Endorphins (opiate drugs occupy same receptor cites) CNS
Substance P the body’s pain neurotransmitter; endorphins are emitted to counter Substance
P’s pain signals
Agonist mimics neurotransmitter
Heroin as an agonist: Mimics the effects of endorphins; explains why some develop addiction
and then later withdrawal symptoms
Antagonist blocks neurotransmitter
Agonist: wants neurotransmitters in the synapse. “I go next!” sounds like “Agonist”
Antagonist: blocks neurotransmitters from being released. Antagonist in a story blocks main
character from achieving goals. Ant prefix means “against”
Curare a potent neurotoxin used as an arrow poison by some native peoples of South America
active ingredients of curare are alkaloids that affect neuromuscular transmission, thereby acting
as muscle relaxants
Curare acts only at muscular synapses and NOT at the synapses of the central nervous system
(curare does not cross the blood-brain barrier)
The blood-brain barrier prevents many low-life forms, such as toxins, that make it into the
blood stream from tainting the brain's pristine nerve cell habitat.
What are the functions of the nervous system’s main divisions? pp. 59-61
the body’s speedy, electrochemical communication system
consists of all the nerve cells of the peripheral and central nervous systems
Central Nervous System (CNS): the brain and spinal cord
Neural networks: Interconnected neurons form networks in the brain. These networks are
complex and modify with growth and experience.
Interconnected neural cells with experience, networks can learn, as feedback strengthens or
inhibits connections that produce certain results
Computer simulations of neural networks show analogous learning.
Reflexes: automatic response. The reflex arc: sensory info enters, brain processes, motor
nerves receive command and act.
Infant reflexes:
1.diving
2.grasping
3.babinski
4.rooting
Dont Give Babies Roofies
Peripheral Nervous System (PNS)
the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the
body
Somatic Nervous System: The division of the peripheral nervous system that controls the body’s
skeletal muscles.
ANS, autonomic nervous system (automatic actions: heartbeat, breathing, etc.)
We activate this during a lab when one partner writes a story about something that made them
very angry or fearful.
One set of nerves, the sympathetic nervous system (SNS), is the fight or flight system, mobilizing
your body; sympathetic NS “Arouses” (fight-or-flight) Key to remembering what sympathetic
means: When we act in sympathy to another we actively seek to help them.
Another set of nerves, the parasympathetic nervous system (PNS) works to slow down the
body’s resources; parasympathetic NS “Calms” (rest and digest)
Autonomic Nervous System: involuntary bodily functions. Autonomic/Automatic
Sympathetic Nervous System: triggers “fight or flight” response. We sympathize for those who
are going through this (when Ms. T banged on student’s desk)
Afferent Nerves/Sensory Nerves: send messages from body to brain.
Efferent Nerves/Motor Nerves: from brain to body. “Eff you and get out!”
Sensory Neurons carry incoming information from the sense receptors to the CNS. PART OF
THE PERIPHERAL N.S., These connect to the spinal cord in back.
The SNS and PNS comprise an opponent process system. They work in opposition leading to
homeostasis, or balance.
Motor Neurons carry outgoing information from the CNS to muscles and glands. These connect
to the spinal cord in front.
Interneurons connect the two neurons. These make reflexes happen. Otherwise, you’d leave
that finger on the burning stove.
Glial Cells
Astrocytes provide nutrition to neurons. Oligodendrocytes and Schwann cells insulate neurons as
myelin.
How does the Endocrine System---the body’s slower communication system---transmit its
messages? pp. 62-63
Endocrine System: endo means within, so these chemicals get secreted into the bloodsteream,
unlike exocrine secretions (sweat, tears, saliva)
the body’s “slow” chemical communication system; a set of glands that secrete hormones into
the bloodstream
Adrenal glands
Part of your endocrine system
They release HORMONES epinephrine and norepinephrine to increase ht. Rt., BP, blood sugar,
etc.
Adrenal glands consist of the adrenal medulla and the cortex. The medulla secretes hormones
(epinephrine and norepinephrine) during stressful and emotional situations, while the adrenal
cortex regulates salt and carbohydrate metabolism.
Hormones are chemicals synthesized by the endocrine glands that are secreted in the
bloodstream. Hormones affect the brain and many other tissues of the body.
Hormones and neurotransmitters are the same. The latter functions quicker in the brain, the
former slower in the body. The former are made in glands, the latter in neurons.
For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar and
feelings of excitement during emergency situations.
Pituitary gland is called the “master gland.” The anterior pituitary lobe releases hormones that
regulate other glands. The posterior lobe regulates water and salt balance.
Pancreas: secretes insulin to regulate sugar in the bloodstream.
Thyroids: Regulate metabolic and calcium rate.
Gonads: Sex glands are located in different places in men and women. They regulate bodily
development and maintain reproductive organs in adults.
TRY the practice questions on pp. 64-65