ap psychology: unit ii introductory psychology: biological bases of behavior everything that is...

AP PSYCHOLOGY: UNIT II

Introductory PsychologyIntroductory Psychology::Biological Bases of Biological Bases of

BehaviorBehavior

Everything that is biological, is simultaneously psychological…

Topic: Neurons and

Neurotransmitters

Paul Broca: (1824 – 1880)

Studied brain lesions and made connection to speech/language

Determined left frontal lobe to be center for language production “Broca’s area”

One of first discoveries of a separation of function between left and right hemispheres

Broca’s aphasia Damage to frontal lobe

Individuals can comprehend speech but have difficulty expressing thoughts

Carl Wernicke (1848 – 1905)

Related nerve diseases to specific areas of the brain

Discovered structure in left temporal lobe controls language comprehension

“Wernicke’s area”

Wernicke’s aphasia Speak in garbled sentences and poor speech

comprehension

Roger Sperry (1913 – 1994)

Studied psychology and zoology

Human beings are of two minds

Two hemispheres can operate independently

Won Nobel Prize (medicine) Split-brain research

Research helped chart map of brain and led to expansion of field

Michael Gazzaniga (1939 - )

Worked under Roger Sperry

Understanding of functional lateralization How some cognitive functions tend to be

dominated by one side or the other

Studied how cerebral hemispheres communicate

Professor of psychology at UC Santa Barbara

PART ONE

The Biological BasesThe Biological Bases: : Cells of the Nervous Cells of the Nervous

SystemSystem

Imagine that you are watching an action-packed movie. As the

tension mounts, your palms sweat and your heart beats faster. You begin shoveling popcorn into your mouth,

carelessly spilling some into your lap. If someone were to

ask you what you were doing in that moment, how would you

respond?

Biological BasesBiological Bases: : CellsCells

The Nervous System An extensive network of specialized cells

that carries information to and from all parts of the body; body’s information system Brain to the body, face and internal organs Senses to the brain

Two Major Types of Cells in the Nervous System Neurons (the basic building blocks) Glia (a neuron’s support system)


Neurons Individual cells;

basic building block of the nervous system

Neurons perform three primary tasks: receive, integrate and transmit information


Afferent Neurons (Sensory Neurons) Carry information from the body’s tissues & sensory

organs to the brain & spinal cord (INWARD; access)

Efferent Neurons (Motor Neurons) Carry information from the brain & spinal cord to the

body’s tissues & sensory organs (OUTWARD; exit)

Interneurons CNS neurons that communicate internally and

intervene between sensory inputs and motor outputs (make reflexes happen)

Dendrites

Soma

Nucleus

Axon (inside)Myelin Sheath

(covering)

Terminal Buttons

Schwann Cell

Node of Ranvier


Basic Parts of a Neuron Soma (“body” in Greek)

Cell body; contains nucleus & chemical “machinery” common to most cells

Dendrites (“tree” in Greek) Branchlike structures that receive information from

other neurons

Axon (“axle” in Greek) Tube-like structure that carries the neural message

away from the soma and to other cells (neurons)


Basic Parts of a Neuron Myelin Sheath

Fatty substance produced by certain glial cells; encases axon; helps insulate, protect & speed the neural impulse

Terminal Branches/Buttons Small knobs that secrete chemicals called

neurotransmitters (chemical messengers)

Synapse (“junction” in Greek) Junction where information is transmitted from one

neuron to another

Real Life Application: NeuronsMyelin Sheath & Multiple

Sclerosis

The importance of myelin is evident in M.S.

In M.S. the myelin sheath degenerates causing neural communication to slow down

Eventually leads to the loss of muscle control


Glia Cells (“glue” in Greek) Provide support for neurons

Deliver nutrients, produce myelin, flush waste & dead neurons and influenceinformation processing

Influence the generation of new neurons during prenatal development

Outnumber neurons 10 to 1; account for 50% of the brain’s total volume

PART TWO

Biological BasesBiological Bases: : The Neural ImpulseThe Neural Impulse

Alan Hodgkin & Andrew Huxley

Biological BasesBiological Bases: : Neural ImpulseNeural Impulse

Alan Hodgkin & Andrew Huxley (1952)Studied squid giant

axon

Unraveled the mystery of the neural impulse

WHY SQUID?

Inside the Neuron

Ions are mostly negative

Outside the Neuron

Ions are mostly positive

Semi-Permeable Fluid

Allows ions to travel both in and out of the neuron


Resting Potential A neuron’s state when it is NOT firing

a neural impulse; a neuron at rest

An inactive neuron has a stable, negative charge (-70 millivolts) In this state the neuron is capable of generating an action potential; ready to fire


Action PotentialA very brief shift in a

neuron’s electrical charge that travels along the axon; begins at the soma Neural messages travel anywhere from 2 mph to 270 mph

Depolarization occurs when positive ions

enter the neuron

making it more prone to fire an action

potential

Hyperpolarization occurs when negative ions

enter the neuron making it less

prone to fire an action potential


Absolute Refractory Period After an action potential, the minimum

length of time during which another action potential cannot begin The “recharging phase” (1-2 milliseconds) The nerve WILL NOT respond to a second

stimulus during this period


Threshold The level of stimulation

required to trigger a neural impulse

All-or-None Principle If a neuron fires it will

ALWAYS fire at the same intensity (100%); the intensity of the stimulus DOES NOT matter

PART THREE

Biological BasesBiological Bases: : The SynapseThe Synapse

Biological BasesBiological Bases: : The SynapseThe Synapse

Synapse A junction between the

axon tip of the sending neuron and the dendrites of the receiving neuron The action potential

CANNOT jump the gap How do action

potentials travel from one neuron to another?


Like a neuron, a toilet has an action potential. When you flush, an “impulse” is sent down the sewer pipe

Like a neuron, a toilet has a refractory period. There is a short delay after flushing when the toilet cannot be flushed again because the tank is being refilled


Like a neuron, a toilet has a resting potential. The toilet is “charged” when there is water in the tank and is capable of being flushed again

Like a neuron, a toilet operates on the all-or-none principle – it always flushes with the same intensity, no matter how much force you apply to the handle

PART FOUR

Biological BasesBiological Bases: : NeurotransmittersNeurotransmitters


Neurotransmitters A chemical messenger

that travels across the synapse from one neuron to the next; transmits information Influences whether the

second neuron will generate an action potential or not


Excitatory Effect A neurotransmitter

effect that makes it MORE likely the receiving neuron will generate an action potential The second neuron is

more likely to fire GREEN LIGHT


Inhibitory Effect A neurotransmitter effect

that makes it LESS likely the receiving neuron will generate an action potential The second neuron is

less likely to fire RED LIGHT


Neurotransmitters bind to the receptors of the receiving neurons in a lock & key mechanism


Agonists Chemical substances that mimic or enhance the

effects of a neurotransmitter on the receptor sites of the next cell

Increases or decreases the activity of that cell, depending on the effect of the original neurotransmitter (excitatory or inhibitory)

ExampleBlack widow venom – floods synapses with ACh

Violent muscle contractions and convulsions

Morphine, a man-made chemical substance, is an endorphin agonist


Antagonists Chemical substances that

block or reduce a cell’s response to the action of other chemicals or neurotransmitters

ExampleCurare is an acetylcholine (ACh) antagonist that blocks motor neurons and paralyzes youBotulin – blocks ACh release – used to paralyze underlying facial muscles


Reuptake Neurotransmitters in the

synapse are reabsorbed into the sending neurons through the process of reuptake This process applies the

brakes on neurotransmitter

action


Acetylcholine (ACh) Characteristics

Located at neuromuscular junctions Involved in muscle action, learning,

attention, memory and arousal

Dysregulation Alzheimer’s Disease

ACh producing neurons deteriorate

Psychopharmacology Curare (antagonist) Botulism (antagonist) Spider venom (agonist)

Is there a connection between

Botox & Acetylcholine??


Dopamine (monoamine) Characteristics

Involved in mood, voluntary movement, learning, attention, motivation & emotion

Dysregulation Parkinson’s Disease Schizophrenia

Psychopharmacology Cocaine (agonist)

OVERSUPPLY or

UNDERSUPPLY?


Norepinephrine (monoamine) Characteristics

Involved in mood, alertness and arousal

Affects parts of the brain where attention and responding actions are controlled

Dysregulation Depressive disorders Attention Hyperactivity Disorder

(ADHD)

Psychopharmacology Adderall (agonist)


Serotonin (monoamine) Characteristics

Involved in sleep, wakefulness, mood, appetite & arousal

Appears to set an “emotional tone”

Dysregulation Depression Obsessive-Compulsive Disorder Eating Disorders

Psychopharmacology Antidepressants (agonists) Ecstasy and LSD (agonists)


GABA (amino acid) Characteristics

The most common inhibitory neurotransmitter Reduces activity of neurons to which it binds

Involved in sleep and the inhibition of movement; aids in the regulation of anxiety

Dysregulation Anxiety disorders Seizure disorders Insomnia

Psychopharmacology Alcohol (agonist) & Valium (agonist)


Glutamate (amino acid) Characteristics

The most common excitatory neurotransmitterOver half of all brain synapses release

glutamate Involved in learning, memory formation and the

development of the nervous system

Dysregulation Schizophrenia Migraines


Endorphins Characteristics

Inhibitory neural regulators; controls the release of other neurotransmitters

Involved in pain relief and response to stressReduce perception of painProduce feeling of euphoria

Dysregulation Heightened state of rage or anxiety

Overdoing their job

Psychopharmacology Morphine and Codeine

ap psychology: unit ii introductory psychology: biological bases of behavior everything that is...

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