Nervous System: Biological Control Center Brain – thinks, calculates, feels, and controls motivation Spinal cord Bundle of long nerves running through

Nervous System: Biological Control Center

Brain – thinks, calculates, feels, and controls motivation

Spinal cord Bundle of long nerves running through

spineConnects brain to every part of body

Biological foundations of Behavior

Neurons: The Units of the Nervous System

Neuron – individual nerve cell Parts of neurons

Cell body: central part of nerve cell; contains nucleus or cell’s control center

Dendrites: small branches extending from cell; receive messages from other neurons

Axons: small branches at other end of neuron; send messages to other neurons


Neurons: The Units of the Nervous System

Neural TransmissionNeurons

Function like wires and batteriesHave sacs filled with fluid chemicals

containing surrounded by a second type of chemical

Ions: positive or negative changed particlesCell membrane

semipermeable in normal resting state

Polarized when negative ions inside cell membrane and positive ions outside


Neural TransmissionNeurons

Depolarization – positive ions enter membrane

All-or-none principle Action potentialMyelin sheath

Average thickness in females is greater

May indicate females process certain information better than males

Multiple sclerosis destroys myelin sheath


Neural Transmission

Neurotransmitters and Synaptic Transmission

Neurons work together throughSynapse Synaptic gapNeurotransmitters: excitatory,

inhibitorySynaptic vesiclesSynaptic terminalsReceptor sites

Brain can be altered by use of drugs


Neurotransmitters and Synaptic Transmission

Glial cellsOutnumber neuronsProduce myelin sheathUses chemical ATP

(adenosine

triphosphate)


Chemicals in brain– Acetylcholine

– Dopamine

– Serotonin

– Norepinephrine

– Glutamate

– Neuropeptides

Divisions of the Nervous System

Central Nervous SystemBrain and spinal cordInterneuron

Peripheral Nervous SystemBranches to all parts of body from CNSAfferent and efferent neurons


Direction of impulse

Muscle contracts and withdraws part being

stimulated

Axion of efferent neuron

Pain receptors in skinAxion of

afferent neuronCell body of interneuron

Cell body of afferent neuron

Dendrite of afferent

neuron

Cell body of efferent neuron

Hot object

Divisions of Peripheral Nervous System

Somatic nervous systemVoluntary movements and skeletal musclesReceives and send messages

Autonomic nervous systemCarries messages to organs, has 2 functions

Essential body functions Emotion


Divisions of Autonomic Nervous System

Sympathetic nervous systemResponds to psychological or physical stressActivates and inhibits organs

Parasympathetic nervous systemHelps maintain balanced regulation of

internal organs and large body musclesStimulates maintenance activities and

energy conservation


Structures and Functions of the Brain

HindbrainRoutine functions that keep body workingThree main parts

Medulla – breathing and reflexes Pons – balance, hearing

Cerebellum – coordinates complex muscle movements


Hindbrain and Midbrain

MedullaMedulla

Pons

Cerebellum

Midbrain

Structures and Functions of the Brain

Reticular formationSpans medulla and ponsInfluence wakefulness, arousal, attention, Muscle control and cardiac

responsiveness

Midbrain Center for postural reflexes linked to

senses


Forebrain: Cognition, Motivation, Emotion, and Action

Forebrain – two distinct areas

Thalamus, hypothalamus, most limbric

system Thalamus – message switching station Hypothalamus – motives and emotions Amygdala system – aggression, emotions Hippocampus – memories


Forebrain

ThalamusThalamus

Hypothalamus

Cerebral Cortex

Forebrain: Cognition, Motivation, Emotion, and Action

Forebrain – two distinct areas

Primarily cerebral cortex Sensory, cognitive, and motor functions Conscious experiences Voluntary actions Language and intelligence


Lobes of the Cerebral CortexLobes – four sections of brain

Frontal lobes – thinking, memory,

decisions Broca’s area – ability to speak Phineas Gage

Association areas – general roles in

cerebral activities


Wernicke’s area

Broca’s area

Motor area SomatosensoryVoluntary

movement and thinking Body sensations

Vision

Hearing

The Brain’s Four Lobes

Images of the Brain at WorkTechniques create images

Electroencephalogram (EEG)Positron emission tomography (PET)Magnetic resonance imaging (MRI)

Functional MRI measures


Functions of the Hemispheres of the Cerebral Cortex


Corpus CallosumCorpus Callosum

Functions of the Left and Right Cerebral Hemispheres

Left cerebral hemisphereLanguage control in 90% of populationAnalyzes logical verbal information

Right cerebral hemisphereProcesses shapes and location of thingsVisual and spatial information

Corpus callosum


Split BrainsSevered corpus

callosum

Psychological experiments reveal processing limitations of hemispheres

Optic chiasm not severed


Hemispheres of the Cerebral Cortex and Emotion

Left hemisphereProcesses positive emotionsStroke in left hemisphere – depression

Right hemisphereProcesses negative emotionsStroke in right hemisphere – no

depression

Plasticity of cortex


Human Diversity: Sex Differences in the Cerebral CortexFemale brain – average size smaller than

that of male brainMore folds and complexGreater surface areaMore accurate in verbal task performanceMore activation in left cerebral

hemisphereMale brain

More activation in right cerebral

hemisphere


The Brain is a Developing SystemBrain structure changes over lifetime

Total brain weight same after age 5Gray matter decreases as white matter

increases in cerebral cortex

White matter: continued myelin growth but decreases after fifth decade of life

Gray matter decrease: neural pruning

Neurogenesis: controversial issue


The Brain is an Interacting System

Cerebral cortex – evaluates threats

Limbic system – process emotional arousal

Motor areas of cortex work with hindbrain and midbrain to coordinate muscular movements

Parallel rather than serial processing


Endocrine System: Chemical Messengers of the Body

Endocrine system – regulation of bodily processesGlands – secrete neuropeptides and

hormonesHormones

Directly regulated by brain Chemically identical to some neurotransmitters

Activate body organs during physical stress or emotional arousal


GlandsPituitary Gland

Largely controlled by hypothalamusRegulates body’s reaction to stress and

resistance to disease

Adrenal glandsPair of glands atop kidneySecrete variety of hormones in emotional

arousal Epinephrine and norepinephrine Cortisol


Islets of LangerhansEmbedded in pancreas – regulate

sugar in blood

Glucagon – causes liver to put sugar in blood stream

Insulin – reduces sugar level in blood


GlandsGonads – produce sex cells

Ovaries and estrogenTestes and testosterone

Thyroid glandRegulation of metabolismSecretes thyroxinSerious deficiency: cretinism, rare

type of mental retardation


GlandsParathyroid glands

Four small glands in thyroidSecrete parathormoneRegulates ion levels in neurons

Too much – lethargy Too little – excessive nervous activity

Pineal glandAttached to top of thalamusSecretes melatonin – regulates moods


Genetic Influences on BehaviorWhat is inherited?

Physical traitsSpecific behavioral patterns

Biological mechanisms of inheritanceGenetic codes

Mendel – science of genetics Genes, chromosomes, and DNA


Genetic Influences on BehaviorBiological mechanisms of inheritance

Sex cells Gametes Fertilization and zygote

Dominant and recessive genes and

traitsChromosome abnormalities

Down syndrome

Genes influence on mental processes


Research on Inheritance in Humans

Studies of twinsMonzygotic: identical twinsDizygotic: fraternal twins

Studies of adopted childrenHeredity and environmental

influences


Biological Foundations of Behavior

Documents

Nervous System: Biological Control Center Brain – thinks, calculates, feels, and controls motivation Spinal cord Bundle of long nerves running through