Transcript EXPLORING PSYCHOLOGY (7th Edition in Modules) David Myers

Neural and Hormonal Systems
Module 3
“…it has been calculated that the number
of possible permutations and combinations
of brain activity,..exceeds the number of
elementary particles in the known
universe.”
Ramachandran in A Brief Tour Of Human Consciousness
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Neuroscience and Behavior
Overview
Neural Communication
 Neurons
 How Neurons Communicate
 How Neurotransmitters Influence Us
The Nervous System
 The Peripheral Nervous System
 The Central Nervous System
The Endocrine System
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History of Mind
Phrenology
In 1800, Franz Gall
suggested that bumps of
the skull represented
mental abilities.
Bettman/ Corbis
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Neural Communication
Neurobiologists and other investigators
understand that humans and animals operate
similarly when processing information.
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Neural Communication
The body’s information system is built from
billions of interconnected cells called neurons.
A nerve cell, or a neuron, consists of many different
parts.
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The cell body
• Contains the cell’s Nucleus
– Round, centrally
located structure
– Directs
metabolism
– No role in neural
signaling
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Dendrites
• Information
collectors
• Receive inputs from
neighboring neurons
• If threshold is
reached the AXON
will generate an
output
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Dendritic Growth
• Dendrites can form
new connections
• Provides room for
more connections to
other neurons
• New connections
are basis for
learning!
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Axon
• The cell’s output
structure
• One axon per cell,
2 distinct parts
– tubelike structure,
terminal branches at
end that connect to
dendrites of other
cells
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Myelin sheath
“Practice makes Myelin, Myelin
makes perfect.”
• Specialized Glial cells
• Acts as an electrical
insulator
• Not present on all
cells
• Increases the speed
of neural signals
down the axon.
Myelin Sheath
Parts of a Neuron link .50
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How neurons communicate
• Neurons communicate by means of an
electrical signal called the Action Potential
• Action Potentials are based on
movements of ions between the outside
and inside of the cell
• When an Action Potential occurs a
molecular message is sent to neighboring
neurons
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Action Potential
A neural impulse. A brief
electrical charge that
travels down an axon and
is generated by the
movement of positively
charged atoms in and out
of channels in the axon’s
membrane.
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Threshold
Threshold: Each neuron receives
excitatory and inhibitory signals from
many neurons.
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Action Potential Properties
All-or-None Response: A strong stimulus can
trigger more neurons to fire, and to fire more
often, but it does not affect the action potentials
strength or speed.
Intensity of an action potential remains the
same throughout the length of the axon.
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Synapse
Synapse [SIN-aps] a junction between the axon
tip of the sending neuron and the dendrite or
cell body of the receiving neuron.
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Neurotransmitters
Neurotransmitters
(chemicals) released
from the sending
neuron travel across
the synapse and bind
to receptor sites on
the receiving neuron.
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Reuptake
Neurotransmitters
in the synapse are
reabsorbed into the
sending neurons
through the process
of reuptake.
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Chemical Messengers
• Neurotransmitters
• Hormones
• Neurohormones
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Types of Neurotransmitters
•
•
•
•
•
•
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Acetylcholine
Serotonin
Norepinephrine
Dopamine
Endorphins
GABA
Glutamate
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Acetylcholine
• Found in
neuromuscular
junction
• Involved in
muscle
movements
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Disruption of Ach Functioning
• Curare - blocks ACh receptors
– paralysis results
• Nerve gases and Black Widow
spider venom - too much ACh leads
to severe muscle spasms and
possible death
• Cigarettes - nicotine works on ACh
receptors
– can artificially stimulate skeletal muscles,
leading to slight, trembling movements
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Alzheimer’s Disease
• Deterioration of memory, reasoning,
and language skills
• Symptoms may be due to loss of
ACh neurons
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Serotonin
Serotonin
pathways are
involved with
mood regulation.
Prozac works by keeping
serotonin in the synapse
longer, giving it more time
to exert an effect
LSD and Seratonin at Nat Geo
2:21
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Dopamine
Important for
movement,
rewards &
pleasure.
Involved with
diseases such as
schizophrenia
and Parkinson’s
disease.
Link dopamine flood at Nat Geo 3:4428
Parkinson’s Disease
• Results from loss of dopamine-producing
neurons
• Symptoms include
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difficulty starting and stopping voluntary movements
tremors at rest
stooped posture
rigidity
poor balance
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Parkinson’s Disease
• Treatments
– L-dopa
– transplants of fetal dopamine-producing
substantia nigra cells
– adrenal gland transplants
– electrical stimulation of the thalamus has
been used to stop tremors
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Oliver Sacks: “Awakenings”
• Patients had suffered from encephalitis lethargica
decades earlier
• Patients were in a frozen or semi-frozen state
• Encephalitis lethargica causes the symptoms of
Parkinson’s disease
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Sacks: Results
L-Dopa
 Sacks administered the experimental drug L-Dopa
• Patients “awoke” from their frozen states
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Sacks: Results & Legacy
• L-Dopa lost its effectiveness, and patients returned to
their frozen state
• The experiment showed the relationship between
encephalitis lethargica and dopamine and between
encephalitis lethargica and Parkinson’s disease
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• Showed how medicine can affect behavior
Norepinephrine
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Arousal
Sympathetic nervous system
“Fight or flight” response
Wakefulness, sleep
Learning
Mood regulation
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Endorphins
• Control pain and
pleasure
• Released in response
to pain
• Morphine and
codeine work on
endorphin receptors
Involved in healing
effects of
acupuncture
•
Link Endorphins at AM 5:12
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Gamma-Aminobutyric Acid
(GABA)
• Main inhibitory neurotransmitter
of the CNS when you sleep
• Benzodiazepines (which include
tranquilizers such as Valium) and
alcohol work on GABA receptor
complexes
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Glutamate
• Major excitatory neurotransmitter
• Too much glutamate (and too
little GABA) associated with
epileptic seizures
• Involved w/memory
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Lock & Key Mechanism
Neurotransmitters bind to the receptors of the
receiving neuron in a key-lock mechanism.
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Agonists
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Antagonists
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The Nervous System Overview
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The Nervous System
Nervous System: Consists of all the nerve cells. It
is the body’s speedy, electrochemical
communication system.
Central Nervous System (CNS): the brain and
spinal cord.
Peripheral Nervous System (PNS): the sensory and
motor neurons that connect the central nervous
system (CNS) to the rest of the body.
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Nervous System
Central
Nervous
System
(CNS)
Peripheral
Nervous
System
(PNS)
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Kinds of Neurons
Sensory Neurons carry
incoming information
from the sense receptors
to the CNS.
Motor Neurons carry
outgoing information
from the CNS to
muscles and glands.
Interneurons connect
the two neurons.
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Central Nervous System
The Spinal Cord and Reflexes
Simple Reflex
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The Nerves
Nerves consist of neural “cables” containing many
axons. They are part of the peripheral nervous
system and connect muscles, glands, and sense
organs to the central nervous system.
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Peripheral Nervous System (PNS)
Somatic Nervous System: The division of the
peripheral nervous system that controls the body’s
skeletal muscles.
Autonomic Nervous System: Part of the PNS that
controls the glands and other muscles.
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Autonomic Nervous System (ANS)
Sympathetic Nervous System: Division of the
ANS that arouses the body, mobilizing its
energy in stressful situations.
Parasympathetic Nervous System: Division of
the ANS that calms the body, conserving its
energy.
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Central Nervous System
The Brain and Neural Networks
Interconnected neurons form networks in the
brain.
Complex Neural Network
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The Endocrine System
The Endocrine
System is the body’s
“slow” chemical
communication
system.
Communication is
carried out by
hormones
synthesized by a set
of glands.
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Hormones vs. Neurotransmitters
• Distance traveled between
release and target sites
• Speed of communication
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Hormones
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.
For example, epinephrine (adrenaline) increases
heart rate, blood pressure, blood sugar, and
feelings of excitement during emergency
situations.
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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.
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The effects of the pituitary are clearly shown here.
Entertainer David Frost stands between the
world’s tallest and smallest man.
The tallest man in history was 8
feet 11 inches tall. He died at the
age of 22, partly as a result of
this defect. The shortest known
person was 23 inches tall when
she died at the age of 19. Today’s
medicines can handle most of
these problems if caught earlier
enough, but these cases show
what happen if the pituitary
gland goes awry.
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• Tallest man
• http://www.youtube.com/watch?v=zL_nklb
ytbY
• Smallest man
• http://www.youtube.com/watch?v=UyJOO
S6raQw
• Tallest woman
• http://www.youtube.com/watch?v=F0V_8Z
XZyzM
• Gigantism at National Geographic 44:55
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Adrenal Glands
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.
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Endocrine Glands
• Thyroid gland – metabolism, calcium
• Pineal gland - sleep and wakefulness
• Pancreas - regulates blood sugar
level
• Ovaries and testes - secrete sex
hormones such as testosterone and
estrogen
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EXPLORING
PSYCHOLOGY
(7th Edition in Modules)
David Myers
PowerPoint Slides
Aneeq Ahmad
Henderson State University
Worth Publishers, © 2008
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• Altering neurons with light at ted talks
18:24
• Recording neuronal activity at ted talks
17:35
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Neurotransmitter
pathways
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