Psy I Winter '16: Chpt. 2 Lecture

mastering the world ofpsychology

CHAPTER

fifth edition

Copyright © 2014, © 2011, © 2008 by Pearson Education, Inc.All Rights Reserved

Biology and Behavior

2

Mastering the World of Psychology, Fifth EditionSamuel Wood | Ellen Green Wood | Denise Boyd

Learning Objectives

2.1 What does the electroencephalogram (EEG) reveal about the brain?

2.2 How do researchers use imaging techniques to study the nervous system?

2.3 What does each part of the neuron do? 2.4 How do neurons transmit messages through

the nervous system?2.5 How do neurotransmitters work?2.6 What are the structures and functions of the

peripheral nervous system?


Learning Objectives

2.7 What are the structures and functions of the central nervous system?

2.8 What are the components of the cerebrum?2.9 What are the specialized functions of the left

and right cerebral hemispheres?2.10 Which functions are associated with each of

the four lobes of the cerebral cortex?2.11 How does the brain change across the

lifespan?2.12 How do the brains of men and women differ?


Learning Objectives

2.13 What are the functions of the glands of the endocrine system?

2.14 How does heredity affect physical and psychological traits?


Overview

• Discovering the Mysteries of the Nervous System

• The Neurons and the Neurotransmitters • The Human Nervous System • A Closer Look at the Thinking Part of

the Brain • Age, Gender, and the Brain • Beyond the Nervous System


Discovering the Mysteries of the Nervous System: EEG and Microelectrode

• Electroencephalogram (EEG)– Electrical activity detected by electrodes

placed on the scalp• Microelectrode

– monitors or stimulates activity of a single neuron

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Discovering the Mysteries of the Nervous System: Imaging Techniques

• CT Scan (Computerized Axial Tomography)– uses a rotating, computerized X-ray

tube – produces cross-sectional images of

brain structures

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• MRI (Magnetic Resonance Imaging) – produces clearer and more detailed

images without exposure to potentially dangerous X-rays of a CT scan

– can be used to find abnormalities in the central nervous system and in other systems of the body

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• PET Scan (Positron Emission Tomography)– used to study normal brain activity and

identify malfunctions – maps patterns of blood flow, oxygen

use, and glucose consumption glucose: food of the brain

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• PET Scan (Positron Emission Tomography)– allows for the study of the action of

drugs and other biochemical substances in the brain and other organs

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• functional MRI (fMRI)– advantages over PET:

Provides images of both brain structure and brain activity

Requires no injections (of radioactive or other material)

Can identify locations of activity more precisely than PET

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• functional MRI (fMRI)– advantages over PET:

Detects changes that take place in less than a second, compared with about a minute for PET

• SQUID (Superconducting Quantum Interference Device) – measures magnetic changes produced

by electric current that neurons discharge when they fire

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The Neurons and the Neurotransmitters: The Structure of the Neuron

• Neuron (NEW-ron) – A specialized cell that conducts

impulses through the nervous system• Neurotransmitters

– Specialized chemicals that facilitate or inhibit the transmission of impulses from one neuron to the next

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• Most neurons are made of three parts:– cell body

contains the nucleus carries out the metabolic functions of the

neuron– dendrites

primary receivers of signals from other neurons

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• Most neurons are made of three parts:– axon

slender, tail-like extension of the neuron sprouts into branches, each ending in a

bulbous axon terminal

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• Axon Terminal – Bulbous end of the axon where signals

move from the axon of one neuron to the dendrites or cell body of another

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• Glial Cells – located in the brain and spinal cord– support neurons, remove waste

products– perform other manufacturing,

nourishing, and cleanup tasks

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Figure 2.1 The Structure of a Typical NeuronA typical neuron has three important parts: (1) a cell body, which carries out the metabolic functions of the neuron; (2) branched fibers called dendrites, which are the primary receivers of the impulses from other neurons; and (3) a slender, tail-like extension called an axon, the transmitting end of the neuron, which sprouts into many branches, each ending in an axon terminal. The photograph shows human neurons greatly magnified.


The Neurons and the Neurotransmitters: Communication between Neurons

• Axon terminals are separated from the receiving neurons by fluid-filled gaps: synaptic clefts.

• Synapse – junction where axon terminal of sending

neuron communicates with receiving neuron

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• Synapse – There may be as many as 100 trillion

synapses in the human nervous system.– A single neuron may form synapses with

thousands of other neurons.

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• A measurable electrical impulse is present with every move or thought.

• Permeability of cell membrane changes– allows ions to move into and out of the

axon

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• Body fluids contain ions.– Ions have positive or negative electrical

charges.– There are normally more negative than

positive ions.– An axon at rest carries about 70

millivolts (relative to the fluid outside the cell).

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Figure 2.2 The Action PotentialThe action potential moves down the axon to the axon terminals.Source: Adapted from Lilienfeld, Lynn, Namy, & Wolf (2009).



• Resting Potential– slight negative electrical potential of the

axon membrane of a neuron at rest• Action Potential

– sudden reversal of the resting potential, initiates firing of neuron

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• "All or None" Law– A neuron either fires completely or does

not fire at all.• Refractory Period

– short resting period after firing during which a neuron cannot fire again

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• Myelin Sheath– white, fatty coating on some axons– makes action potential travel up to 100

times faster• Nodes of Ranvier

– gaps in the myelin sheath– Neural impulse is regenerated at each

node

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• Receptors – Protein molecules on the surfaces of

dendrites and cell bodies that have distinctive shapes and will interact only with specific neurotransmitters

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The Neurons and the Neurotransmitters: Neurotransmitters

• Neurotransmitters – chemical substances that transmit

messages between neurons– released into synapse by axon terminals

of sending neuron– bind to receptor sites on dendrites of

receiving neuron– taken back into axon terminal by the

process of reuptake

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Figure 2.3 Synaptic TransmissionSending neurons transmit their messages to receiving neurons by electrochemical action. When a neuron fires, the action potential arrives at the axon terminal and triggers the release of neurotransmitters from the synaptic vesicles. Neurotransmitters flow into the synaptic cleft and move toward the receiving neuron, which has numerous receptors. The receptors will bind only with neurotransmitters whose molecular shapes match their enclosed volumes. Neurotransmitters influence the receiving neuron to fire or not to fire.



• How do synaptic vesicles continue to pour out neurotransmitters yet maintain a ready supply of neurotransmitter?– The cell body of the neuron is always

working to manufacture more of the neurotransmitter.

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• How do synaptic vesicles continue to pour out neurotransmitters yet maintain a ready supply of neurotransmitter?– Unused neurotransmitters in the

synaptic cleft may be broken down into components and reclaimed by the axon terminal to be recycled.

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• How do synaptic vesicles continue to pour out neurotransmitters yet maintain a ready supply of neurotransmitter?– Reuptake: the neurotransmitter is taken

back into the axon terminal, intact and ready for immediate use.

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Table 2.1 Major Neurotransmitters and Their Functions


Figure 2.4 The HumanNervous System The nervous system is divided into two parts: the peripheral nervous system and the central nervous system. The diagram shows the relationships among the parts of the nervous system and provides a brief description of the functions of those parts.


The Human Nervous System:The Peripheral Nervous System

• The peripheral nervous system consists of two subdivisions.– somatic nervous system

consists of all sensory nerves and motor nerves

– autonomic nervous system transmits messages between the central

nervous system and glands, cardiac muscle, and smooth muscles

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The Human Nervous System:The Peripheral Nervous System

• Sympathetic Nervous System– mobilizes the body's resources during

stress and emergencies• Parasympathetic Nervous System

– brings heightened bodily responses back to normal following an emergency

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Figure 2.5 The Autonomic Nervous SystemThe autonomic nervous system consists of (1) the sympathetic nervous system, which mobilizes the body’s resources during emergencies or stress, and (2) the parasympathetic nervous system, which brings the heightened bodily responses back to normal afterward. This diagram shows the opposite effects of the sympathetic and parasympathetic nervous systems on various parts of the human body.Source: Lilienfeld, Lynn, Namy, & Woolf (2009).


The Human Nervous System:The Central Nervous System

• Spinal Cord– best thought of as extension of the

brain– transmits messages between the brain

and the peripheral nervous system– can act without help from the brain to

protect the body from injury

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The Human Nervous System:The Central Nervous System

• Spinal Cord– Withdrawal or Spinal Reflex

triggered by a painful stimulus involves 3 types of neurons:

– sensory-afferent– motor-efferent– interneuron

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Figure 2.6 The Spinal ReflexThe sequence that begins with a sensory stimulus (such as touching something hot) and ends with a behavioral response (withdrawing the hand) involves sensory neurons, interneurons, and motor neurons.Source: Adapted from Lilienfeld, S., Lynn, S., Namy, L., & Woolf, N. (2009).


Figure 2.7 Major Structures of the Human BrainThis drawing shows some of the major structures of the brain with a brief description of the function of each. The brainstem contains the medulla, the reticular formation, and the pons.


The Human Nervous System:The Hindbrain

• Structures control vital functions.• Brainstem

– begins at the site where the spinal cord enlarges as it enters the skull

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• Hindbrain – a link between the spinal cord and the

brain that contains structures that regulate physiological functions, including heart rate, respiration, and blood pressure

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• Medulla– controls heartbeat, blood pressure,

breathing, coughing, swallowing• Reticular Formation

– plays a crucial role in arousal and attention

– screens sensory messages entering the brain

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• Pons– plays a role in body movement– influences sleep and dreaming

• Reticular formation– a structure in the brainstem that plays a

crucial role in arousal and attention and that screens sensory messages entering the brain

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• Cerebellum– helps the body execute smooth, skilled

movements– regulates muscle tone and posture

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The Human Nervous System:The Midbrain

• The midbrain links the physiological functions of the hindbrain to the cognitive functions of the forebrain.

• Substantia Nigra– controls unconscious motor movements

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The Human Nervous System:The Forebrain

• Forebrain – largest part of the brain– functions include memory, logic, and

self-awareness• Thalamus

– relay station for information flowing into or out of the brain

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• Hypothalamus– regulates hunger, thirst, sexual

behavior, body temperature, and a variety of emotional behaviors

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• Limbic system – a group of structures in the brain,

including the amygdala and hippocampus, that are collectively involved in emotional expression, memory, and motivation

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Figure 2.8 The Principal Structures in the Limbic SystemThe amygdala plays an important role in emotion; the hippocampus is essential in the formation of new memories.



• Amygdala– part of the limbic system – plays important role in emotion

• Hippocampus– part of the limbic system– central role in storing new memories,

responses to new or unexpected stimuli, and navigational ability

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Figure 2.9 Two Views of the Cerebral Hemispheres(a) The two hemispheres rest side by side like two matched halves, physically connected by the corpus callosum. (b) An inside view of the right hemisphere.


A Closer Look at the Thinking Part of the Brain: Components of the Cerebrum

• Cerebral Hemispheres– left and right halves of cerebrum

• Corpus Callosum– connects the two hemispheres

• Cerebral Cortex– thin outer covering of cerebrum– responsible for higher mental processes

of language, memory, and thinking

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• The cerebral cortex contains 3 types of areas. – Sensory Input Areas

vision, hearing, touch, pressure, and temperature register

– Motor Areas control voluntary movement

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• The cerebral cortex contains 3 types of areas. – Association Areas

house memories and are involved in thought, perception, and language

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A Closer Look at the Thinking Part of the Brain: The Cerebral Hemispheres

• Lateralization – the specialization of one of the cerebral

hemispheres to handle a particular function

• Left Hemisphere– controls the right side of the body– handles most language functions– specialized for mathematics and logic

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A Closer Look at the Thinking Part of the Brain: The Cerebral Hemispheres

• Right Hemisphere– controls left side of body– processes music– interprets emotional messages

conveyed by tone of voice and gestures– is specialized for visual-spatial relations

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Figure 2.10 Lateralized Functions of the BrainAssigning functions to one hemisphere or the other allows the brain to function more efficiently.Source: Based on Gazzaniga (1983).


A Closer Look at the Thinking Part of the Brain: The Split Brain

• Corpus callosum is absent or has been surgically modified.

• Only the verbal left hemisphere can report what it sees.

• The left hemisphere does not see what is flashed to the right hemisphere; the right hemisphere is unable to report verbally what it has viewed.

LO 2.9


Figure 2.11 Testing a Split-Brain PersonUsing special equipment, researchers are able to study the independent functioning of the hemispheres in split-brain patients. In this experiment, when a visual image (an orange) is flashed on the right side of the screen, it is transmitted to the left (talking) hemisphere. When asked what he sees, the split-brain patient replies, “I see an orange.” When an image (an apple) is flashed on the left side of the screen, it is transmitted only to the right (nonverbal) hemisphere. Because the split-brain patient’s left (language) hemisphere did not receive the image, he replies, “I see nothing.” But he can pick out the apple by touch if he uses his left hand, proving that the right hemisphere “saw” the apple.Source: Based on Gazzaniga, M. (1983).


Figure 2.12 The Four Lobes of the Cerebral CortexThis illustration of the left cerebral hemisphere shows the four lobes: (1) the frontal lobe, including the motor cortex and Broca’s area; (2) the parietal lobe, with the somatosensory cortex; (3) the occipital lobe, with the primary visual cortex; and (4) the temporal lobe, with the primary auditory cortex and Wernicke’s area.


A Closer Look at the Thinking Part of the Brain: The Four Cerebral Lobes

• Frontal Lobes• Prefrontal Cortex

– The part of the frontal lobes directly behind the forehead that controls executive processing, the coordination of multiple brain activities in pursuit of cognitive goals

• Motor Cortex– controls voluntary body movement

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• Broca's Area– located in frontal lobe– usually in the left hemisphere– controls speech production

• Aphasia (uh-FAY-zyah) – a loss or impairment of the ability to use

or understand language, resulting from damage to the brain

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• Association Areas– areas involved in thinking, planning for

the future, impulse control

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• Parietal Lobes– somatosensory cortex

located at the front of the parietal lobes where touch, pressure, temperature, and

pain register in the cortex

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• Occipital Lobes– involved in reception and interpretation

of visual information• Primary Visual Cortex

– area at the rear of the occipital lobes where vision registers in the cortex

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• Temporal Lobes• Primary Auditory Cortex

– area in each temporal lobe where hearing registers in the cortex

• Wernicke's Area– language area in the left temporal lobe

involved in comprehending spoken language and formulating coherent speech and written language

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Age Gender and the Brain:The Ever-Changing Brain

• The brain grows in spurts from conception until well into adulthood.

• Each growth spurt also seems to involve a different brain area.– The spurt that begins around age 17

and continues into the early 20s mainly affects the frontal lobes

Age, Gender, and the Brain:The Ever-Changing Brain

LO 2.11



• Synaptogenesis– occurs in spurts throughout the life span

• Pruning– process through which the developing

brain eliminates unnecessary or redundant synapses follows periods of synaptogenesis

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• Stroke – an event in the cardiovascular system in

which a blood clot or plug of fat blocks an artery and cuts off the blood supply to a particular area of the brain

• Myelination– development of myelin sheaths around

axons

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• Myelination– begins prior to birth but continues well

into adulthood• Plasticity

– the capacity to adapt to changes is maintained throughout life

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Age Gender and the Brain: Gender Differences in the Brain

• Women's Brains– Equal proportions of gray and white

matter in the left and right hemispheres– More gray matter in the area of the

brain that controls emotions may explain women's superior ability to

perceive emotions

Age, Gender, and the Brain: Gender Differences in the Brain

LO 2.12



• Women's Brains– Navigational Information

use right parietal cortex and right frontal cortex

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• Men's Brains– Lower proportion of white matter in the

left hemisphere than in the right may explain men's superior ability in

spatial tasks– Navigational Information

use left hippocampus

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Figure 2.13 The Endocrine SystemThe endocrine system is a series of glands that manufacture and secrete hormones. The hormones travel through the circulatory system and have important effects on many bodily functions.


Beyond the Nervous System:The Endocrine System

• Endocrine System (EN-duh-krin)– system of ductless glands

manufacture hormones secretes hormones into bloodstream

– hormone chemical substance that is manufactured

and released in one part of the body and affects other parts of the body

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• Endocrine Glands– pituitary gland

"master gland" releases hormones that activate other

endocrine glands– pineal gland

secretes melatonin, which controls sleep/wakefulness cycle

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• Thyroid Gland– located below the voice box – produces thyroxine

regulates rate of food metabolization• Parathyroid Gland

– produces parathyroid hormone helps the body absorb minerals from the

diet

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• Thymus Gland– produces thymosin– regulates immune system

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• Adrenal Gland– releases hormones that prepare the

body for emergencies and stressful situations

• Pancreas – the endocrine gland responsible for

regulating the amount of sugar in the bloodstream

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• Gonads– ovaries in females– testes in males– produce sex hormones

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Beyond the Nervous System: Genes and Behavioral Genetics

• Genes– segments of DNA located on

chromosomes – transmit all heredity traits

• Chromosomes– 46 chromosomes (23 pairs) contain

20,000 to 25,000 genes– 22 matching pairs called autosomes;

23rd pair are sex chromosomes

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• Genotype – An individual's genetic makeup

• Phenotype – An individual's actual characteristics

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• Dominant-Recessive Pattern– dominant

It is only necessary that one gene be present on chromosome pair for a given trait to be expressed.

– recessive Two genes are required on the

chromosome pair for trait expression.

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• Polygenetic Inheritance– Many genes influence a particular

characteristic.• Multifactorial inheritance

influenced by genes and environmental factors

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• Sex-Linked Inheritance– involves genes on the X and Y

chromosomes example: red-green color blindness

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• Behavioral Genetics– investigates the effects of heredity and

environment on behavior• Twin Studies

– examine identical (monozygotic) and fraternal (dizygotic) twins in order to compare similarities and differences in twin pairs

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• Adoption Studies– compare adopted children's abilities and

traits to those of adoptive parents and biological parents

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