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Chapter 1: What is Psychology?
Chapter 2Biology and Psychology
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The Nervous System: On Being Wired
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LO1 Describe the nervous system, including neurons, neural impulses, and neurotransmitters
Neurons
Neurons
Receive and pass messages
Cell body, dendrites (cellulipetal), axon (cellifugal)
Glial cells
Nourish and insulate neurons
Direct growth of neurons
Remove waste products
3
Truth or Fiction? The human brain is larger than that of any other animal. FALSE A human brain weighs about 3 pounds, but the brains of elephants and whales may be four times as heavy. However, our brains account for a greater part of our body weight than do those of elephants or whales.
glial cells cells that nourish and insulate neurons, direct their growth, and remove waste products from the nervous system
dendrites rootlike structures, attached to the cell body of a neuron, that receive impulses from other neurons
axon a long, thin part of a neuron that transmits impulses to other neurons from branching structures called terminal buttons
myelin a fatty substance that encases and insulates axons, facilitating transmission of neural impulses
Neurons
Afferent Neurons
Transmit messages from sensory receptors to the spinal cord and brain
Efferent Neurons
- Transmit messages from brain or spinal cord to muscles and glands
Interneurons
- form all neural wirings within the CNS
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Truth or Fiction? A single cell can stretch all the way from your spine to your toe. TRUE A single cell can stretch all the way from your spine to your toe.
afferent neurons - neurons that transmit messages from sensory receptors to the spinal cord and brain. Also called sensory neurons
efferent neurons neurons that transmit messages from the brain or spinal cord to muscles and glands. Also called motor neurons
Neurotransmitters
Excitatory neurons
Cause other neurons to fire
Inhibitory neurons
Prevent other neurons from firing
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The Anatomy of a Neuron
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Figure 2.1. The Anatomy of a Neuron. Messages enter neurons through dendrites, are transmitted along the trunk-like axon, and then are sent from axon terminal buttons to muscles, glands, and other neurons. Axon terminal buttons contain sacs of chemicals called neurotransmitters. Neurotransmitters are released into the synaptic cleft, where many of them bind to receptor sites on the dendrites of the receiving neuron.
Go to 4ltrpress.cengage.com/psych to access an interactive version of this figure.
Firing: Neuron to Neuron
Synapse
Fluid-filled gap (Synaptic cleft) between
Axon terminal from transmitting neuron, and
Dendrite of receiving neuron
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synapse a junction between the axon terminals of one neuron and the dendrites or cell body of another neuron
Neurotransmitters
Neurotransmitters
Chemical substances that communicate from one neuron to another
Synaptic vesicles/clefts
Contain neurotransmitters in the axon terminals
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neurotransmitters chemical substances involved in the transmission of neural impulses from one neuron to another
Neural Impulse
Electrochemical messages that travel within neurons
Resting potential
Neuron is not responding to other neurons
degradation
Action potential
Conduction of neural impulse along axon
depolarization
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Truth or Fiction? Messages travel in the brain by means of electricity. TRUE The messages are within neurons. Communication between neurons, however, is carried out quite differently.
neural impulse the electrochemical discharge of a nerve cell, or neuron
polarize to ready a neuron for firing by creating an internal negative charge in relation to the body fluid outside the cell membranes
resting potential the electrical potential across the neural membrane when it is not responding to other neurons
depolarize to reduce the resting potential of a cell membrane from about 70 millivolts toward zero
action potential the electrical impulse that provides the basis for the conduction of a neural impulse along an axon of a neuron
Firing: Neuron to Neuron
Firing
Conduction of neural impulse along the length of a neuron
Threshold
Incoming messages reach a strength at which neuron will fire
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Firing: Neuron to Neuron
All-or-none principle
Every time a neuron fires, it transmits an impulse of the same strength.
Refractory period
Period of recovery time between firings
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Truth or Fiction? A brain cell can send out hundreds of messages each second and manage to catch some rest in between. TRUE During the refractory period, the neuron is insensitive to messages from other neurons and will not fire
all-or-none principle the fact that a neuron fires an impulse of the same strength whenever its action potential is triggered
refractory period a phase following firing during which a neuron is less sensitive to messages from other neurons and will not fire
Neurotransmitters
Receptor site
On dendrite of receiving neuron
Reuptake
Neurotransmitters reabsorbed
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receptor site a location on a dendrite of a receiving neuron tailored to receive a neurotransmitter
Neurotransmitters of Interest to Psychologists
Acetylcholine (ACh)
Controls muscle contractions, learning, remembering, controlling stag of sleep
Paralysis
Epinephrine
Adrenal medulla; central core of the adrenal glands
Dopamine
Pleasure, voluntary movement, learning, memory
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acetylcholine (Ach) a neurotransmitter that controls muscle contractions
hippocampus a part of the limbic system of the brain that is involved in memory formation
Neurotransmitters of Interest to Psychologists
Norepinephrine
Excitatory neurotransmitter
Accelerates heart rate, affects eating, linked to activity levels, learning and remembering
Serotonin
Emotional arousal, pain, eating and sleep
Eating disorders, alcoholism, depression, aggression, insomnia
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serotonin a neurotransmitter, deficiencies of which have been linked to affective disorders, anxiety, and insomnia
Neurotransmitters of Interest to Psychologists
Glutamic Acid (glutamate)
Direct effects in axos
seizure
Gamma-aminobutyric acid (GABA)
Inhibitory may help relax anxiety reactions
Depression
Endorphins
Occur naturally within the brain and bloodstream
Inhibit pain
Neurotransmitters of Interest to Psychologists
Glycine
Inhibitory
Located at the spinal cord and lower portion of the brain
The Divisions of the Nervous System
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Figure 2.4 The Divisions of the Nervous System. The nervous system contains two main divisions: the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal cord. The peripheral nervous system contains the somatic and autonomic systems. In turn, the autonomic system has sympathetic and parasympathetic divisions. Go to 4ltpress.cengage.com/pysch to access an interactive version of this figure.
Parts of the Nervous System
Central Nervous System
Brain and spinal cord
Peripheral Nervous System
Sensory (afferent) and motor (efferent) neurons
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nerves a bundle of axons from many neurons
central nervous system the brain and spinal cord
peripheral nervous system the part of the nervous system consisting of the somatic nervous system and the autonomic nervous system
Peripheral Nervous System
Somatic Nervous System
Sensory and motor neurons
Transmits messages to the brain and purposeful body movements from the brain
Autonomic Nervous System
Regulates glands and muscles of internal organs
Contains sympathetic and parasympathetic divisions
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somatic nervous system the division of the peripheral nervous system that connects the central nervous system with sensory receptors, skeletal muscles, and the surface of the body
autonomic nervous system (ANS) the division of the peripheral nervous system that regulates glands and activities such as heartbeat, respiration, digestion, and dilation of the pupils
Branches of Autonomic Nervous System
Sympathetic
Most active during emotional responses
Spend the bodys reserves of energy
Parasympathetic
Most active during processes that restore bodys reserve of energy
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Truth or Fiction? Fear can give you indigestion. TRUE The sympathetic division of the ANS predominates when we feel fear or anxiety, and these feelings can therefore cause indigestion.
sympathetic the branch of the ANS that is most active during emotional responses, such as fear and anxiety, that spend the bodys reserves of energy
parasympathetic the branch of the ANS that is most active during processes (such as digestion) that restore the bodys reserves of energy
The Parasympathetic and Sympathetic Branches of the Autonomic Nervous System
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Figure 2.5 The Parasympathetic and Sympathetic Branches of the Autonomic Nervous System (ANS). The parasympathetic branch of the ANS generally acts to replenish stores of energy in the body. The sympathetic branch is most active during activities that expend energy. The two branches of the ANS frequently have antagonistic effects on the organs they service.
Central Nervous System
Spinal Cord
Transmits messages from sensory receptors to the brain and from the brain to muscle and glands
Spinal Reflex
Simple, unlearned response to stimulus
Gray matter - nonmyelinated
White matter - myelinated
22
spinal cord a column of nerves within the spine that transmits messages from sensory receptors to the brain to muscles and glands throughout the body
spinal reflex a simple, unlearned response to a stimulus that may involve only two neurons
gray matter the grayish neurons and neural segments that are involved in spinal reflexes
white matter axon bundles that carry messages from and to the brain
The Reflex Arc
The Reflex Arc. Reflexes are inborn, stereotyped behavior patterns that have apparently evolved because they help individuals adapt to the environment even before they can understand and purposefully manipulate the environment. Here we see a cross section of the spinal cord, highlighting a sensory neuron and a motor neuron, which are involved in the knee-jerk reflex. In some reflexes, interneurons link sensory and motor neurons.
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Figure 2.6 The Reflex Arc. Reflexes are inborn, stereotyped behavior patterns that have apparently evolved because they help individuals adapt to the environment even before they can understand and purposefully manipulate the environment. Here we see a cross section of the spinal cord, highlighting a sensory neuron and a motor neuron, which are involved in the knee-jerk reflex. In some reflexes, interneurons link sensory and motor neurons.
The Brain: Wider Than the Sky
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LO2 List the structures of the brain and their functions.
The Parts of the Human Brain
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Figure 2.9 The Parts of the Human Brain. This view of the brain, split top to bottom, shows some of the most important structures.
Three layers of the BRAIN
Central core
Limbic System
Cerebral Hemisphere (cerebrum)
Central Core
Functions
Basic life processes, breathing, pulse, arousal, movement, balance, sleep, early stage of processing sensory information.
Structures and Functions of the Brain
Hindbrain
Medulla
Breathing, swallowing, digestion, heart rate posture
Pons
sleep
Cerebellum
Little brain
muscle coordination and balance
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medulla an oblong area of the hindbrain involved in regulation of heartbeat and respiration
pons a structure of the hindbrain involved in respiration, attention, and sleep and dreaming
cerebellum a part of the hindbrain involved in muscle coordination and balance
Structures and Functions of the Brain
Middle of Central Core
Thalamus
Relay station for sensory stimulation
Transmit message from sense organs to cerebral cortex & from cerebral cortex to cerebellum and medulla
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thalamus an area near the center of the brain involved in the relay of sensory information to the cortex and in the functions of sleep and attention
hypothalamus a bundle of nuclei below the thalamus involved in body temperature, motivation, and emotion
Structures and Functions of the Brain
Middle of Central Core
Hypothalamus
Regulates body temperature, motivation and emotion, autonomic function control, endocrine function control, homeostasis, motor function control
Hunger, thirst, sexual behavior, caring for offspring, aggression, sleep-wake cycle
Structures and Functions of the Brain
Reticular Activation System
From hindbrain, ascends through midbrain into lower part of forebrain
Vital to attention, sleep, arousal
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reticular activation system a part of the brain involved in attention, sleep, and arousal
Structures and Functions of the Brain
Forebrain
Limbic System
Amygdala, hippocampus and parts of hypothalamus
Involved in memory and emotion
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limbic system a group of structures involved in memory, motivation, and emotion that forms a fringe along the inner edge of the cerebrum
amygdala a part of the limbic system that apparently facilitates stereotypical aggressive responses
Structures and Functions of the Brain
Cerebrum
Responsible for thinking and language
Cerebral Cortex
the wrinkled surface area (gray matter) of the cerebrum
Corpus Callosum
Connects two hemispheres
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cerebrum the large mass of the forebrain, which consists of two hemispheres
cerebral cortex - the wrinkled surface area (gray matter) of the cerebrum
corpus callosum a thick fiber bundle that connects the hemispheres of the cortex
The Cerebral Cortex
Outer layer of cerebrum
Two Hemispheres
Four Lobes
Frontal, Parietal, Temporal and Occipital
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The Lobes of the Cerebral Cortex
Occipital Lobe
Vision
Temporal Lobe
Hearing and Auditory functions
Parietal Lobe
Somatosensory Cortex, speech centers
Frontal Lobe
Motor Cortex, memory processing, emotion
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Truth or Fiction? If a surgeon were to stimulate a certain part of your brain electrically, you might swear that someone had stroked your leg. TRUE The action would be sensed in the somatosensory cortex.
somatosensory cortex the section of cortex in which sensory stimulation is projected. It lies just behind the central fissure in the parietal lobe.
motor cortex the section of cortex that lies in the frontal lobe, just across the central fissure from the sensory cortex; neural impulses in the motor cortex are linked to muscular responses throughout the body.
Thinking, Language, and the Cortex
Association areas
Not primarily involved in sensation or motor activity
Responsible for learning, thought, memory and language
Association areas in frontal lobe
Responsible for executive functions
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Executive functions such as problem solving, making plans, and decision making.
Association Areas
Posterior association areas
senses
Association areas of the parietal lobe
Locating objects in sensory space and maintaining maps of the environment
Left Brain, Right Brain
Hemispheres do not act independently
Functions overlap and they respond simultaneously
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The Endocrine System
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Endocrine System
Comprised of ductless glands that release hormones into the bloodstream
Hormones
Regulate growth, metabolism and some behaviors
Maintain steady bodily states
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LO3 Explain the role of the endocrine system and list the endocrine glands.
gland an organ that secretes one or more chemical substances such as hormones, saliva, or milk
endocrine system the bodys system of ductless glands that secrete hormones and release them directly into the bloodstream
hormone a substance secreted by an endocrine gland that regulates various body functions
The Endocrine Glands
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Figure 2.14. The Endocrine Glands.
Pituitary and the Hypothalamus
Pituitary gland
Lies below hypothalamus
Labeled as master gland
Hormones secreted by pituitary gland
Hypothalamus regulates pituitary gland activity
50
pituitary gland the gland that secretes growth hormone, prolactin, antidiuretic hormone, and other hormones
Growth hormone regulates growth of muscles, bones, and glands
Prolactin regulates maternal behavior in lower mammals and stimulates production of milk in women
Vasopressin inhibits production of urine when body fluids are low
Oxytocin stimulates labor in pregnant women, connected with maternal behavior
Pineal Gland
Pineal gland
Secretes melatonin
Helps regulate sleep-wake cycle
May affect onset of puberty
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Adrenal Glands
Adrenal glands
Located above the kidneys
Cortical steroids
increase resistance to stress, anxiety, pain and emotional events
promote muscle development
Epinephrine and norepinephrine
Helps arouse body in threatening situations
52
Adrenal cortex secretes cortical steroids increase resistance to stress; promote muscle development; cause liver to release stored sugar; makes more energy available in emergency
Adrenal medulla secretes epinephrine and norepinephrine Helps arouse body in threatening situations
Testes and Ovaries
Testosterone
produced by testes (smaller amounts from adrenal gland)
male sex characteristics
Estrogen and progesterone
produced by ovaries (smaller amounts from testes)
female sex characteristics
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Evolution and Heredity
54
LO4 Describe evolutionary psychology and the connections between heredity, behavior, and mental processes.
Chromosomes
Receive 23 chromosomes from fathers sperm and 23 chromosomes from mothers egg cell
23rd pair of chromosomes are sex chromosomes
XX female
XY male
Down syndrome
Chromosomal abnormality
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sex chromosomes the 23rd pair of chromosomes, whose genetic material determines the sex of the individual
Down syndrome a condition caused by an extra chromosome on the 21st pair and characterized by mental deficiency, a broad face, and slanting eyes