2.0thebiologyofmind

8/7/2019 2.0TheBiologyofMind

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Cindy Avendano

Chapter 2 The Biology of Mind

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Chapter 2

The Biology of Mind

Researchers seeking to understand the biology of the mind have discoveredthat:

y The body is composed of cellsy Among these are nerve cells thatconduct electricity and talkto another by

sending chemical messages across a tiny gap that separates them

y Specific brain systems serve specific functions (though not the functions Gallsupposed)

1. Franz Gall invented phrenology,a popular but ill-fated theory thatclaimed bumps on the skull could reveal our mental abilities and our

characteristic traits.

y We integrate information processed in these different brain systems toconstruct our experience of sights and sounds, meanings and memories, painand passion.

y Our adaptive brain is wired by our experience.Biological psychologists study the links between biological activity andpsychological events. B.P continue to expand our understanding of sleep and

dreams, depression, schizo, hunger and sex, stress and disease.

We are each a system composed of subsystems that are in turn composed of

even smaller subsystems.

y Tiny cells organize to form such body organs as the stomach, heart, andbrain.

y These organs form larger systems for digestion, circulation, andinformation processing.

y We are biopsychosocial systems, and to understand our behavior, we needto study how these biological, psychological, and social-cultural system

work and interact.

Neuron is a nerve cell; the basic building block of the nervous system.

How do neurons transmit information?

Sensory neurons carry messages from the bodys tissues and sensory organs

inward to the brain and spinal cord, for processing.

The brain and spinal cord then send instructions out to the bodys tissues via the

motor neurons.


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Between the sensory input and motor output, information is processed in the

brains internal communication system via its interneurons. Our complexity resides

mostly in our interneuron systems.

We have: Few million sensory neurons, a few million motor neurons, and billionsand billions of interneurons. Each of these consists of a cellbodyand its branching

fibers.

The bushy dendrite fibers receive information and conduct it toward the cell

body.

From there, the cells axon passes the message along to other neurons or tomuscles or glands.

Axons SPEAK.Dendrites LISTEN.

Dendrites are short.Axons are sometimes very long, projecting several feet through the body.

Much as home electrical wire is insulated, so a layer of fatty tissue, called the

myelin sheath, insulates the axons of some neurons and helps speed their

impulses.

y As myelin is aid down up to about age 25, neural efficiency, judgment,and self-control grows.

If the myelin sheath degenerates, multiple sclerosisresults:

Communication to muscles slows, with eventual loss of muscle control.

Depending on the type of fiber, a neural impulse travels at speeds from

2mph to 200+ mph. Brain is more complex than a computer, but

SLOWER at executing simple responses.

Most neuron signals are EXCITATORY, like acceleration.Others are INHIBITORY, like breaking.

(51) Synapse the junction between the axon tip of the sending neuron

and the dendrite or cell body of the receiving neuron.The tiny gap at this

junction is called the synaptic gap or synaptic cleft.

Neurotransmitters chemical messengers that cross the synaptic gaps

between neurons.When released by the sending neuron,

neurotransmitters travel across the synapse and bind to receptor sites on

the receiving neuron, thereby influencing whether that neuron will

generate a neural impulse.


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Reuptake a neurotransmitters re-absorption by the sending neuron .

(process in which the sending neuron reabsorbs the excess

neurotransmitters.)

NEURAL COMMUNICATION

HOWNEURONS COMMUNICATE:

1. Electrical impulses (action potentials) travel down a neurons axonuntil reaching a tiny junction known as a synapse.

2. When action potential reaches an axon terminal, it stimulates therelease of neurotransmitter molecules.These molecules cross thesynaptic gap and bind to receptor sites on the receiving neuron.This

allows electrically charged atoms to enter the receiving neuron and

excite or inhibit a new action potential.3. The sending neuron normally reabsorbs excess neurotransmitter

molecules, a process called reuptake.

1. WHATARE NEURONS, AND HOW DO THEYTRANSMIT INFORMATION?

Sensory Neurons carry incoming information from sense receptors to the brain and

spinal cord.

Motor neurons carry information from the brain and spinal cord out to the muscles

and glands.

Interneurons communicate within the brain and spinal cord and between sensory

and motor neurons.

A neuron sends signals through its axons, and receives signals through its branchingdendrite. If the combined signals are strong enough, the neuron fires, transmitting

an electrical impulse (the action potential) down its axon by means of a chemistry toelectricity process.

2. HOW DO NERVE CELLS COMMUNICATE WITH OTHER NERVE CELLS?

WHEN ACTION POTENTIALS REACHTHE ENDOF AN AXON (THE AXON

TERMINALS), THEY STIMULATE THE RELEASE OF neurotransmitters.Neurotransmitters carry a message from the sending neuron across a synapse to

receptor sites on a receiving neuron.The sending neuron, in a process called

reuptake, then normally absorbs the excess neurotransmitter molecules in the

synaptic gap.The receiving neuron, if the signals from that neuron and others arestrong enough, generates its own action potential and relays the message to other

cells.

3.HOW DO NEUROTRANSMITTERS INFLUENCEBEHAVIOR, AND HOW DODRUGS AND OTHER CHEMICALS AFFECT NEUROTRANSMISSION?

Each neurotransmitter travels a designated path in the brain and has a particular

effect on behavior and emotions.


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Acetylcholine affects muscle action, learning, and memory.

Endorphins are natural opiates released in response to pain and exercise.

Drugs and other chemicals affect communication at the synapse. Agonists excite by

mimicking particular neurotransmitters or by blocking their reuptake. Antagonists

inhibit a particular neurotransmitters release or block its effect.

4. WHATARE THE FUNCTIONS OF THE NERVOUS SYSTEMS MAINDIVISIONS?

Central nervous system (CNS) the brain & spinal cord.

Peripheral Nervous System (PNS) connects the CNS to the rest of thebody by means of nerves.

1. somatic nervous system voluntary control of the skeletalmuscles.

2. Autonomic nervous system through its sympathetic andparasympathetic divisions, controls involuntary muscles andglands.

The Endocrine System

5. HOW DOES THE ENDOCRINE SYSTEM THEBODYS SLOWERINFORMATION SYSTEM TRANSMIT ITS MESSAGES?

Its a set of glands that secrete hormones into the bloodstream, there

they travel through the body and affect other tissues, including the

brain.The endocrine systems master gland, the pituitary, influences

hormone release by other glands.The brains hypothalamus influences

the pituitary gland, which influences other glands, which release

hormones, which in turn influence the brain.

CONSCIOUSNESS

1. WHAT ISTHE BIOLOGICAL RHYTHM OFOUR SLEEP?5 sleep stages in 90 minutes:

Leaving the alpha waves (the relatively slow brain waves of a relaxed, awakestate) we descend into transitional STAGE 1SLEEP: often with sensations of

falling or floating.

STAGE 2 sleep: in which we spend the most time, follows about 20 minutesafter Stage 1, with its characteristic sleep spindles.

Stage 3-4: together lasts about30 mins, with large, slow delta waves(the

large, slowbrain waves associated with deep sleep)

Then goes back up from 4,3,2, then 1 then REM.REM happens about an hour after falling asleep. MOSTDreams occurs in this

5th stage (aka paradoxical sleep) of internal arousal but outward paralysis.

During a normal nights sleep, periods ofStages 3&4 sleep shorten and REM

sleep lengthens.

2. WHAT ISTHE FUNCTION OFDREAMS?5 views of function of dreams:


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(1.) Freudian: to provide a safety value, with manifest content (or storyline) acting as a censored version of latent content (some underlying

meaning that gratifies our unconscious wishes.)

(2.) The information-processing perspective: to sort out the daysexperiences and fix them in memory.

(3.) Brain stimulation: to preserve neural pathways in the brain.(4.) The activation-synthesis explanation: to make sense of neural static

our brain tries to weave into a story line.

(5.) The brain-maturation/cognitive-development perspective: Dreamsrepresent the dreamers level of development, knowledge, and

understanding.** Most sleep theorists agree that REM sleep and its associated dreams serve an

important function, as shown by the REM REBOUND that occurs following REMdeprivation.

3. WHAT ARE TOLERANCE, DEPENDENCE, AND ADDICTION, ANDWHAT ARESOME COMMON MISCONCEPTIONS ABOUT ADDICTION?

Psychoactive drugs alter perceptions & moods.Their continued use producestolerance (need of larger dose for same effect) and may lead to physical &

psychological dependence.

Addiction is compulsive drug craving & use.

THREE COMMON MISCONCEPTIONS ABOUT ADDICTION:

1. addictive drugs quickly corrupt2. therapy is always required to overcome addiction3. the concept of addiction can meaningfully be extended beyond chemical

dependence to a wide range of other behaviors.

4.WHY DOSOME PEOPLE BECOE REGULAR USERSOF CONSCIOUSNESS-ALTERING

DRUGS?-Psychological factors: stress, depression, hopelessness

-social factors (peer pressure)both combine to lead many people to experiment with and sometimes become

dependent on drugs. Cultural and ethnic groups have differing rates of drug use.

Some people may be biologically more likely to become dependent on drugs such asalcohol.

As oxygen deprivation turns off the brains inhibitory cells, neural activity increases

in the visual cortex. (in relation to NEAR DEATH EXPERIENCES)

Chapter 4

NATURE, NURTURE, AND HUMAN DIVERSITY

Collectivist cultures place a premium on preserving group spirit and

making sure others never lose face.


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INDIVIDUALISMs benefits can come at the cost of more loneliness, more

divorce, and more homicide.

CONCEPT:

Self (I) independent; ; interdependentWhat Matters (i) ME- personal achievement, rights/liberties, self-

esteem ; ; US group goals and solidarity, soc responsibility and

relationships, family duty

GENDER & SOCIALPOWER:

-men place more importance on power & achievement-as leaders men tend to be more directive & autocratic

- women tend to be more democratic, more welcoming of subordinatesparticipation in decision making.

-girls = more interdependent than males (teen girls spend more time withfriends and less time along)

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