Chapter 2- The Biology of Behavior

Question 1

Biological psychology

Answer 1

The scientific study of the links between biological (genetic, neural, hormonal) and psychological processes. (Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or bio psychologists.)

Question 2

Neuron

Answer 2

A nerve cell; the basic building block of the nervous system.

Question 3

Dendrites

Answer 3

A neuron’s often bushy, branching extensions that receive messages and conduct impulses toward the cell body.

Question 4

Axon

Answer 4

The neuron extension that passes messages through its branches to other neurons or to muscles or glands.

Question 5

Myelin sheath

Answer 5

A fatty tissue layer segmentally encasing the axons os some neurons; enables vastly greater transmissions speed as neural impulses hop from one node to the next.

Question 6

Glial cells

Answer 6

Cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory.

Question 7

Action potential

Answer 7

A neural impulse; a brief electrical charge that travels down an axon.

Question 8

Why are psychologists concerned with human biology?

Answer 8

Psychologists working from a biological perspective study the links biology and behavior. We are bio psychosocial systems, in which biological, psychological, and social-cultural factors interact to influence behavior.

Question 9

What are neurons, and how do they transmit information?

Answer 9

Neurons are the basic building blocks of the nervous system, the body’s speedy electrochemical information system. A neuron receives signals through its branching dendrites, and sends signals through its axons. Some axons are encased in a myelin sheath, which enables faster transmission. Glial cells provide myelin, and the support, nourish, and protect neurons; they may also play a role in learning and thinking. If the combined signals received by a neuron exceed a minimum threshold (about negative 55 millivolts), the neuron fires, transmitting an electrical impulse (the action potential) down its axon by means of a chemistry-to-electricity process. The neuron’s reaction is an all-or-none process. Absolute or relative refractory periods are tiny (millisecond) breaks between action potentials.

Question 10

Threshold

Answer 10

The level of stimulation required to trigger a neural impulse.

Question 11

Refractory period

Answer 11

A brief resting pause that occurs after a neuron has fires; subsequent action potentials cannot occur until the axon returns to its resting state.

Question 12

All-or-none response

Answer 12

A neuron’s reaction of either firing (with a full-strength response) or not firing.

Question 13

Synapse

Answer 13

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.

Question 14

When a neuron fires an action potential, the information travels through the axon, the dendrites, and the cell body, but not in that order. Place these three structures in the correct order.

Answer 14

Dendrites, cell body, axon

Question 15

How does our nervous system allow us to experience the difference between a slap and a tap on the back?

Answer 15

Stronger stimuli (the slap) cause more neurons to fire and to fire more frequently than happens with weaker stimuli (the tap).

Question 16

How do nerve cells communicate with other nerve cells?

Answer 16

When action potentials reach the end of an axon (the axon terminals), they stimulate the release of neurotransmitters. These chemical messengers 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, the normally reabsorbs the excess neurotransmitter molecules in the synaptic gap. If in coming signals are strong enough, the receiving neuron generates its own action potential and relays the message to other cells.

Question 17

What happens in the synaptic gap?

Answer 17

Neurons send neurotransmitters (chemical messengers) across this tiny space between one neuron’s terminal branch and the next neuron’s dendrite or cell body.

Question 18

What is reuptake? What two things can happen to excess neurotransmitters after a neuron reacts?

Answer 18

Reuptake occurs when excess neurotransmitters are reabsorbed by the sending neuron. They can also drift away or be broken down by enzymes.

Question 19

How do neurotransmitters influence behavior, and how do drugs and other chemicals affect neurotransmitters?

Answer 19

Neurotransmitters travel designated pathways in the brain and may influence specific behaviors and emotions. Acetylcholine (ACh) affects muscle action, learning, and memory. Endorphins are natural opiates released in response to pain and exercise. Drugs and other chemical affect brain chemistry at synapses. Agonists increase a neurotransmitter’s action, and may do so in various ways. Antagonists decrease a neurotransmitter’s action by blocking production or release.

Question 20

Neurotransmitters

Answer 20

Chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

Question 21

Reuptake

Answer 21

A neurotransmitter’s reabsorption by the sending neuron.

Question 22

Endorphins

Answer 22

“morphine within”-natural, opiate-like neurotransmitters linked to pain control and to pleasure.

Question 23

Agonist

Answer 23

A molecule that increases a neurotransmitter’s action.

Question 24

Antagonist

Answer 24

A molecule that inhibits or blocks a neurotransmitter’s action.

Question 25

Nervous system

Answer 25

The body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.

Question 26

Central nervous system (CNS)

Answer 26

The brain and spinal chord

Question 27

Peripheral nervous system (PNS)

Answer 27

The sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

Question 28

Nerves

Answer 28

Bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sense organs.

Question 29

Sensory (afferent) neurons

Answer 29

Neurons that carry incoming information from the sensory receptors to the brain and spinal chord.

Question 30

Motor (efferent) neurons

Answer 30

Neurons that carry outgoing information from the brain and spinal chord to the muscles and glands.

Question 31

Interneurons

Answer 31

Neurons within the brain and spinal cord; communicate internally and process information between the sensory inputs and motor outputs.

Question 32

Somatic nervous system

Answer 32

The division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skeletal nervous system.

Question 33

Autonomic nervous system (ANS)

Answer 33

The part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.

Question 34

Sympathetic nervous system

Answer 34

The division of the autonomic nervous system that arouses the body, mobilizing it’s energy.

Question 35

Serotonin, dopamine, and endorphins are all chemical messengers called ————.

Answer 35

Neurotransmitters

Question 36

Curare poisoning paralyzes its victims by blocking ACh receptors involved in muscle movements. Morphine mimics endorphin actions. Which is agonist, and which is an antagonist?

Answer 36

Morphine is an agonist, and curare is an antagonist.

Question 37

Parasympathetic nervous system

Answer 37

The division of the autonomic nervous system that calms the body, conserving its energy.

Question 38

Reflex

Answer 38

A simple, automatic response to a sensory stimulus, such as the knee-jerk response.

Question 39

Endocrine system

Answer 39

The body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.

Question 40

Hormones

Answer 40

Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.

Question 41

What bodily changes does your ANS direct before and after you give an important speech?

Answer 41

Responding to this challenge, your ANS sympathetic division will arouse you. It accelerates your heartbeat, raises your blood pressure and blood sugar, slows your digestion, and cools you with perspiration. After you give the speech, your ANS parasympathetic division will reverse these affects.

Question 42

Adrenal glands

Answer 42

A pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

Question 43

Pituitary glands

Answer 43

The endocrine system’s most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.

Question 44

What are the functions of the nervous system’s main divisions, and what are the three main types of neurons?

Answer 44

The central nervous system (CNS)-the brain and the spinal cord-is the nervous system’s decision maker. The peripheral nervous system (PNS), which connects the CNS to the rest of the body by means of nerves, gathers information and transmits CNS decisions to the rest of the body. The two main PNS divisions are the somatic nervous system (which enables voluntary control of the skeletal muscles) and the autonomic nervous system (which controls involuntary muscles and glands by means of its sympathetic and parasympathetic divisions). Neurons cluster into working networks. There are 3 types of neurons: (1) Sensory (afferent) neurons carry incoming information from sensory receptors to the brain and spinal cord. (2) Motor (efferent) neurons carry information from the brain and spinal cord out to the muscles and glands. (3) Interneurons communicate within the brain and spinal cord and between sensory and motor neurons.

Question 45

How does the endocrine system transmit information and interact with the nervous system?

Answer 45

The endocrine system is a set of glands that secrete hormones into the blood stream, where they travel through the body and affect other tissues, including the brain. The endocrine system’s master gland, the pituitary, influences hormone release by other glands, including the adrenal glands. In an intricate feedback system, the brain’s hypothalamus influences the pituitary gland, which influences other glands, which release hormones, which in turn influence the brain.

Question 46

Lesion

Answer 46

Tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue.

Question 47

Electroencephalogram (EEG)

Answer 47

An amplified recording of the waves of electrical activity sweeping across the brain’s surface. These waves are measured by electrodes placed on the scalp.

Question 48

PET (positron emission tomography) scan

Answer 48

a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.

Question 49

MRI (magnetic resonance imaging)

Answer 49

A technique that uses magnetic fields and radio waves to produce computer generated images of soft tissue. MRI scans show brain anatomy.

Question 50

fMRI (functional MRI)

Answer 50

A technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function as well as structure.

Question 51

How do neuroscientists study the brain’s connections to behavior and mind?

Answer 51

Clinical observations and lesioning reveal the general effects of brain damage. Electrical, chemical, or magnetic stimulation can also reveal aspects of information processing in the brain. MRI scans show anatomy. EEG, PET, and fMRI (functional MRI) recordings reveal brain function.

Question 52

Nerves from the left side of the brain are mostly linked to the ——————- side of the body, vice versa.

Answer 52

Right

Question 53

Brain stem

Answer 53

The oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brain stem is responsible for automatic survival functions.

Question 54

Medulla

Answer 54

The base of the brain stem; controls heartbeat and breathing.

Question 55

Thalamus

Answer 55

The brain’s sensory control center, located on top of the brain stem; it directs messages to the sensor receiving areas in the cortex and transmits replies to the cerebellum and medulla.

Question 56

What structures make up the brain stem, and what are the functions of the brain stem, thalamus, reticular formation, and cerebellum?

Answer 56

The brain stem, the oldest part of the brain, is responsible for automatic survival functions. Its components are the medulla (which controls heartbeat and breathing), the pons (which helps coordinate movements and control sleep), and reticular formation (which affects arousal). The thalamus, sitting above the brain stem, acts as the brain’s sensory control center. The cerebellum, attached to the back of the brain stem, enables nonverbal learning and skill memory, helps coordinates muscle movement and balance, and also helps process sensory information.

Question 57

Reticular formation

Answer 57

A nerve network that travels through the brain stem into the thalamus and plays important role in controlling arousal.

Question 58

Cerebellum

Answer 58

The “little brain” at the back of the brain stem, functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory.

Question 59

Limbic system

Answer 59

Neural system (including the amygdala, hypothalamus, and hippocampus) located below the cerebral hemispheres; associated with emotions and drives.

Question 60

Amygdala

Answer 60

Two lima-bean-sized neural clusters in the limbic system, linked to emotion.

Question 61

Hypothalamus

Answer 61

A neural structure lying below (hypo) the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via pituitary gland, and is linked to emotion and reward.

Question 62

What are the limbic system’s structures and functions?

Answer 62

The limbic system is linked to emotions, memory, and drives. Its neural centers include the amygdala (involved in response of aggression and fear); the hypothalamus (involved in various bodily maintenance functions, pleasurable rewards, and the control of the endocrine system); and the hippocampus (which processes conscious memories). The hypothalamus also controls the pituitary (the “master gland”) by stimulating it to trigger the release of hormones.

Question 63

Hippocampus

Answer 63

A neural center located in the limbic system; helps process explicit memories for storage.

Question 64

Cerebral cortex

Answer 64

The intricate fabric of inter connected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center.

Question 65

Frontal lobes

Answer 65

Portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgements.

Question 66

Parietal lobes

Answer 66

Portion of the cerebral cortex lying at the top of the head and toward the back; receives sensory input for touch and body position.

Question 67

Occipital lobes

Answer 67

Portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields.

Question 68

Temporal lobes

Answer 68

Portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear.

Question 69

Motor cortex

Answer 69

An area at the rear of the frontal lobes that controls voluntary movements.

Question 70

What are the functions of the various cerebral cortex regions?

Answer 70

The cerebral cortex has two hemispheres, and each hemisphere has 4 lobes: the frontal, parietal, occipital, and temporal. Each lobe performs many functions and interacts with other areas of the cortex. The motor cortex, at the back of the frontal lobes, controls voluntary movements. The somatosensory cortex, at the front of the parietal lobes, registers and processes body touch and movement sensations. Body parts requiring precise control (in the motor cortex) or those that are especially sensitive (in the somatosensory cortex) occupy the greatest amount of space. Most of the brain’s cortex-the major portion of each of the four lobes-is devoted to uncommitted associations areas, which integrate information involved in learning, remembering, thinking, and other higher-level functions. Out mental experiences arise from coordinate brain activity.

Question 71

Somatosensory cortex

Answer 71

Area at the front of the parietal lobes that registers and processes body touch and movement sensations.

Question 72

Association areas

Answer 72

Areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.

Question 73

Plasticity

Answer 73

The brain’s ability to change, especially during childhood, by reorganizing after damage or by rebuilding new pathways based on experience.

Question 74

Neurogenesis

Answer 74

The formation of new neurons.

Question 75

To what extent can a damaged brain reorganize itself, and what is neurogenesis?

Answer 75

If one hemisphere is damaged early in life, the other will pick up many of its functions by reorganizing or building new pathways. This plasticity diminishes later in life. The brain sometimes mends itself by forming new neurons, a process known as neurogenesis.

Question 76

What do split brain’s reveal about the functions of our two brain hemispheres?

Answer 76

Split-brain research (experiments on people with a severed corpus callosum) has confirmed that in most people, the left hemisphere is the more verbal, and that the right hemisphere excels in visual perception and the recognition of emotion. Studies of healthy people with intact brains confirm that each hemisphere makes unique contributions to the integrated functioning of the brain.

Question 77

Corpus callosum

Answer 77

The large band of neural fibers connecting the two brain hemispheres and carrying messages between them.

Question 78

Split brain

Answer 78

A condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them.

Question 79

What are chromosome, DNA, genes, and the human genome? How do behavior geneticists explain our individual differences?

Answer 79

Genes are the biochemical units of heredity that make up chromosomes, the threadlike coils of DNA. When genes are “turned on” (expressed), they provide the code for creating the proteins that form our body’s building blocks. Most human traits are influenced by many genes acting together. The human genome is the shared genetic profile that distinguishes humans from other species, consisting at an individual level of all the genetic material in an organism’s chromosomes. Behavior geneticists study the relative power and limits of genetic (our heredity) and environmental influences on behavior.

Question 80

How do twin and adoption studies help us understand the effects and interactions of nature and nurture?

Answer 80

Studies of identical (monozygotic) twins versus fraternal (dizygotic) twins, separated twins, and biological versus adoptive relatives allow researchers to tease apart the influence of heredity and environment. Research studies on separated identical twins maintain the same genes while testing the effects of different home environments. Studies of adoptive families let researchers maintain the same home environment while studying the effects of genetic differences. Heritable individual differences (in traits such as height and weight) do not necessarily explain gender or ethnic group differences. Shared family environments have little effect on personality, though parenting does influence other factors (such as attitudes).