Transcript Introduction to Psychology

Module 3
Neural and Hormonal Systems
Neural Communication
 Neurons
 How Neurons Communicate
 How Neurotransmitters Influence Us
The Nervous System
 The Peripheral Nervous System
 The Central Nervous System
The Endocrine System
History of Mind
Phrenology
Bettman/ Corbis
In 1800, Franz Gall
suggested that bumps of
the skull represented
mental abilities. His
theory, though incorrect,
nevertheless proposed
that different mental
abilities were modular.
The Nervous System
 Neuron
 a nerve cell
 the basic building block of the nervous system
 Approx. 100 billion neurons (1011)
 Approx. 300-400 trillion synapses (1014)
Hummm???
• How many is 400 trillion really?
The Nervous System
 Nervous System
 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
 Peripheral Nervous System (PNS)
 the sensory and motor neurons that connect the central
nervous system (CNS) to the rest of the body
The Nervous System
 Nerves
 neural “cables” containing many axons
 part of the peripheral nervous system
 connect the central nervous system with muscles,
glands, and sense organs
The Nervous System
 Sensory Neurons
 neurons that carry incoming information from the
sense receptors to the central nervous system
 Motor Neurons
 carry outgoing information from the CNS to
muscles and glands
The Nervous System
 Interneurons
 CNS neurons that internally communicate and
intervene between the sensory inputs and motor
outputs
Central Nervous System
The Brain and Neural Networks
Interconnected neurons form networks in the
brain. Theses networks are complex and modify
with growth and experience.
Complex Neural Network
Neural Communication
 Dendrite
 the bushy, branching extensions of a neuron that receive
messages and conduct impulses toward the cell body
 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
 enables vastly greater transmission speed of neutral
impulses
Neural Communication
Threshold
Threshold: Each neuron receives
excitatory and inhibitory signals from
many neurons. When the excitatory
signals minus the inhibitory signals
exceed a minimum intensity (threshold)
the neuron fires an action potential.
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.
Synapse
Synapse [SIN-aps] a junction between the axon
tip of the sending neuron and the dendrite or
cell body of the receiving neuron. This tiny gap
is called the synaptic gap or cleft.
Neurotransmitters
Neurotransmitters
(chemicals) released
from the sending
neuron travel across the
synapse and bind to
receptor sites on the
receiving neuron,
thereby influencing it to
generate an action
potential.
Reuptake
Neurotransmitters in
the synapse are
reabsorbed into the
sending neurons
through the process of
reuptake. This process
applies the brakes on
neurotransmitter
action.
Neural Communication
How Neurotransmitters Influence Us
A particular pathway in the brain may use
only one or two neurotransmitters and
particular neurotransmitters may have
particular effects on behavior and emotions
How Neurotransmitters Influence Us
Serotonin pathways are
involved with mood
regulation.
From Mapping the Mind, Rita Carter, © 1989
University of California Press
Dopamine Pathways
Dopamine pathways
are involved with
diseases such as
schizophrenia and
Parkinson’s disease.
From Mapping the Mind, Rita Carter, © 1989
University of California Press
Neurotransmitters
Lock & Key Mechanism
Neurotransmitters bind to the receptors of the
receiving neuron in a key-lock mechanism.
Agonists
Antagonists
How Neurotransmitters Influence Us
Endorphins [en - DOR-fins]: “morphine within”—
natural, opiatelike neurotransmitters linked to
pain control and to pleasure.
Drugs and other chemicals affect brain chemistry
at synapses: Agonist molecules bind to a
neurotransmitter’s receptor and mimics its effects.
Antagonists bind to receptors and block a
neurotransmitter’s functioning.
Peripheral Nervous System
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.
The Nervous System
 Autonomic Nervous System
 the part of the peripheral nervous system that
controls the glands and the muscles of the internal
organs (such as the heart)
 Sympathetic Nervous System
 division of the autonomic nervous system that
arouses the body, mobilizing its energy in stressful
situations
 Parasympathetic Nervous System
 division of the autonomic nervous system that
calms the body, conserving its energy
Nervous System
Autonomic Nervous System (ANS)
Sympathetic NS
“Arouses”
(fight-or-flight)
Parasympathetic NS
“Calms”
(rest and digest)
A Simple Reflex
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.
Hormones
Hormones are chemical messengers that are
manufactured by the endocrine glands,
travel through the bloodstream, and affect
other tissues..
For example, epinephrine (adrenaline) increases
heart rate, blood pressure, blood sugar, and
feelings of excitement during emergency
situations.
The Endocrine System
adrenal [ah - DREEN-el] glands: pair of endocrine
glands that sit just above the kidneys and secrete
hormones (epinephrine and norepinephrine) that
help arouse the body in times of stress.
pituitary gland: the endocrine system’s most
influential gland. Under the influence of the
hypothalamus, it regulates growth and controls
other endocrine glands.