Transcript 1. Receptor cells

The Biological Foundations of
Behavior
• The nervous system: the most complicated
system in human body where billions of
interconnected cells radiate all over the body.
• Specialized Cells of nervous system include:
1. Receptor cells: Embedded in sense organs,
(seeing – hearing – smelling – tasting –
touching). receive various types of stimulation
from environment, which are then transmitted
to the brain.
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2. Effector cells: Brain sends motor signals to
the effector cells embedded in muscles and
glands.
3. Neurons: Specialized to conduct signals
from one part to another, (connect receptor
cells to effector cells).
4. Nerve: long, fibrous parts of many neurons
bundled together, and run through the bodies.
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Division of nervous system:
• 1- Central Nervous System (CNS): consists of
brain and spinal cord.
• 2-Peripheral Nervous System (PNS): Branching
out from the CNS and leading to all parts of the
body .
• Neurons from PNS convey signals from receptor
cells to the spinal cord and brain (afferent
pathway).
• neurons transmit messages from brain and spinal
cord to effectors cells (efferent pathway).
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• *Efferent pathway has two divisions :
• Somatic nervous system: it controls actions
that are under voluntary control.
• Autonomic nervous system :control
muscles of internal organs ( the heart,
intestine, blood vessels) and glands, usually
automatic or involuntary.
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• Autonomic nervous system has two
divisions : (opposite effects).
a. Sympathetic nervous system:
• In emergency situations as meeting a snake,
lead to increase blood sugar, heart rate and
blood pressure, and inhibiting digestion
(Fight- Flight- Fright response)
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b. Parasympathetic Nervous System:
• -Dominates under relaxation conditions and
tends to conserve body's energy.
• -After eating large meal, it works to aid
digestion, at the same time decreasing heart
rate and blood flow to skeletal muscles
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Division of the nerves system
(Look in your book please)
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Composition of neuron cell:
• A- Cell body: the life support center of the
cell.
• B- Dendrites: receive messages transmitted
from other neurons (antenna of neurons).
• C- Axons: carries neural signals to affect
the muscle fibers
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Types of neuron
1- Sensory neurons: carry information form
sense organs to the brain & spinal cord.
2-Motor neurons: carry signals from brain
and spinal cord to muscles and glands .
3-Inter-neurons: connect neuron to other
neurons .
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Brain
• Structurally the brain is divided into the
cerebrum, cerebellum, brain stem, and
limbic system.
• (1) CEREBRUM
• The cerebrum is divided into two
hemispheres:
• (2) CEREBELLUM: center for
coordination of movements and postural
adjustments.
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(3) Brain Stem: Includes the midbrain, Pons,
and medulla oblongata.
• Medulla oblongata: contains vital centers for
respiration and cardiovascular functions.
(4) Limbic System: located above the brain
stem that includes:
- The hypothalamus is involved in temperature
regulation, appetite control, endocrine
function…etc.
• Hippocampus is involved in emotional
arousal and memory.
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Neurotransmission:
- Neurons communicate information with one
another by sending electrochemical messages
from neuron to neuron.
• Neurotransmitters:
- Chemical substances manufactured in the
neuron, aid in the transmission of information
throughout the body.
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Major Neurotransmitters in Psychology
1-Dopamine:(excitatory).
- Control of complex movements, motivation,
cognition, and regulation of emotional
responses.
2 Nor epinephrine (Noradrenalin) :
• plays a role in changes in attention, learning
and memory, sleep and wakefulness, and
mood regulation.
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Major Neurotransmitters in Psychology…cot.
3- Epinephrine (adrenaline):
- Controls fight-or-flight response in anxiety
disorders.
4- Serotonin: (inhibitory):
- Control of sleep ,wakefulness, emotions and
sexual behavior.
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Major Neurotransmitters in Psychology…cot.
5- Gamma-Amino Butyric Acid (GABA):
- Drugs that increase GABA function used to
treat anxiety and induce sleep.
6- Acetylcholine: (excitatory or inhibitory).
- affect the sleep/wake cycle and to signal
muscles to become active.
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Sensation and Perception
• Sensation:
(The process where by stimulation of receptor
cells like eye, nose, ear …etc., send nerve
impulses to the brain, where they register a
touch, sound, color …etc).
• Perception:
- (process where the brain interprets sensation
giving them order and meaning).
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Sensation and Perception…cont.
- Without sensation: perception couldn’t
occur, without perception sensations without
meaning.
- Impaired perception cause (illusion).
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Stimulus
(Any form of energy (sound, light, heat, and
pressure) to which an organism is capable of
responding).
• Stimuli and sensation have a cause and
effect relationship.
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Factors affects stimulus detection:
- (1) The intensity of stimulus.
- (2) Background noise interfere with stimulus
detection.
- (3) Motivation (rewards or punishments).
-(4) Prolonged constant stimulation: lead to
sensory adaptation.
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How do perceptual processes
develop?
1. Empiricist view of perceptual
development:
- Babies enter the world with little or no
ability to see depth, form, and perceptual
constancy’s.
- Infants learn adult like perceptions on the
basis of cues the environment provides .
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2. Nativist view of perceptual development:
• Not all perceptual process are learned, some
arise from the way our sensory system
work, e.g. feeling of hunger or diaper
wetting.
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• 3- Interactionism view of perceptual
development:
- Through the interaction of both biological
factors & experience perceptual process
develop.
- what we see, hears, feel, and so forth, is
partly the results of how our sensory systems
are programmed and partly the result of what
we are exposed to.
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• *Expectations and perceptions:
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• Psychologists have studied two ways in
which learning and experience mold our
expectations which in turn shape our
perception
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• 1-Perceptual set:
• A frame of mind that “ sets” a person to
perceive things in a certain way. We
perceive what we think we should perceive.
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• - Perceptual sets establish expectations that
guide our perception, Example person who
was bitten by snake in the dark in specific
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area. The sight of snake become a
• 2- Perceptual schema:
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• Mental representation of objects and events
against which incoming data are compared
and interpreted.
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• - General knowledge of the world in the
form of schemas also shape our
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expectations and hence our knowledge.