Psychology in Your Life Chapter 2 Summary

Chapter 2 Summary THE NERVOUS SYSTEM - Why do psychologists study the nervous system?  The nervous system is the source of all behavior. It controls all thoughts and behaviors.  The nervous system is shaped by our experiences and behaviors. Plasticity is how the nervous system always changes as we learn things without losing its overall structure. - The nervous system is a network of many cells in the brain and body, and the thing behind what you think, feel, or do. - The nervous system has three basic functions a. To receive sensory input b. To process information c. To respond to the information - The two divisions of the nervous system a. Central nervous system: consists of the brain and the spinal cord b. Peripheral nervous system: consists of the nerve cells outside the brain and spinal cord (skin, muscles, etc) Note: PNS has sensory neurons, which take in information, and motor neurons, which take out information. The PNS receives information (from our five senses) and transfers it to the CNS. After that, the CNS collects the information and evaluates it, then sends it back to PNS to perform specific behaviors. - Both divisions are built of smaller units called neurons. Individual neurons receive, collect, and transfer information in the nervous system. - The network of neurons sending and receiving sensory signals (the ones from our five senses) make possible the complex aspects of human mental activity and behavior. - Four parts of a neuron a. Dendrites: branchlike extensions which receive signals from other neurons b. Cell body: in which the information received from other neurons is collected (center of the action) c. Axon: along which electrical impulses are transferred Note: Electrical impulses are information in the form of electrochemical (“brain thing”) signal. Note: A nerve is a collection of axons which carry information between the brain and other locations in the body. d. Terminal buttons: knoblike forms at the end of the axon (vesicles, transporter molecules) - Other important terms: a. Synapse: the place where communication happens between neurons b. Neurotransmitters: a gap between the sending neurons and the receiving neurons. COMMUNICATION BETWEEN NEURONS - Communication within a neuron a. Resting potential – no communication, negative electoral charge inside the neuron b. Action potential – communication  Positive ions enter the membrane of the axon  Ions move down the axon, carrying a positive electrical charge  Resting membrane potential is quickly restored  Cell body to terminal buttons - Neurons are communicating with each other to let the nervous system receive information, process it, and respond to it. - Three phases of neural communicating: 1. The transmission phase: electrical signals are passed along the axon and neurotransmitters are released from the terminal buttons 2. The reception phase: the dendrites of neurons receive signals from sending neurons 3. The integration phase: neurons evaluate the incoming signals - The neuron is covered with a membrane, which separates the inside of the neuron from the outside. - A membrane allows some particles to pass through, which are electric chemicals called ions (sodium and potassium). The movement of ions lets neurons communicate, which is regulated by the membrane. - The neuron begins in a resting state, where the electric inside the neuron is negative (influenced by the ions). - A stimulation causes positive sodium ions to move through the membrane and into the neuron. If it is stimulated enough, it fires an action potential down the axon to the terminal buttons. Note: Stimulation is a raising level of nervous activity - Sodium ions continue to enter the neuron and potassium ions leave the neuron. During the refractory state, the neuron is less responsive and is less likely to fire an action potential. - The stimulated neuron may transfer information to other neurons through an action potential, which travels fast along the axon, which is possible because of myelin sheath. - To communicate, a neuron fires an action potential, depending on how much stimulation the neuron receives. It sends information across the synapse and connect to the receiving neuron’s dendrites. - The neuron that sends the information is called the presynaptic neuron, and the one which receives it is called the postsynaptic neuron. - Receptors are specialized forms that respond to certain types of neurotransmitters. Each receptor can be stimulated by only one type of neurotransmitters. - Synaptic communication is terminated when neurotransmitter is removed from the synapse. Two ways that neurotransmitters are removed from the synapse. 1. When the neurotransmitters are reabsorbed by the presynaptic neuron in reuptake. Note: Reuptake is the process by which a neurotransmitter is reabsorbed by the presynaptic neuron. 2. Enzymes destroy the neurotransmitters while they are in the synapse. Note: Enzymes are specific chemicals which break down other particles. - Enzyme degradation is when different enzymes break down different neurotransmitters. - Neurotransmitters  Chemical messengers released when action potential reaches the terminal button  Carry message across the synapse - Neurons can produce signals of two types 1. Excitatory: excites the neuron 2. Inhibitory: inhibit the neuron The thousands of excitatory and inhibitory signals which are received are collected within the cell body of the neuron. NEUROTRANSMITTERS’ INFLUENCES - Drugs that enhance the actions of neurotransmitters are called agonists. Meanwhile, drugs that inhibit the actions of neurotransmitters are called antagonists. - The receptor can be affected by either a neurotransmitter or a drug that resembles the neurotransmitter, because they are chemically similar to naturally occurring neurotransmitters. - Common neurotransmitters a. Acetylcholine: responsible for motor control between nerves and muscles, involved in complex mental processes, and influences attention, memory, learning, and sleeping. Note: Acetylcholine is critical to making memories. Note: Neuromuscular junction is the point at which the nerve fiber that starts in your central nervous system reaches out to your muscle. Note: Acetylcholine that comes from the ponds is responsible for dreaming. b. Norepinephrine: involved in states of arousal and alertness (direct the spotlight). Note: Epinephrine (a hormone, not a neurotransmitter) can produce an adrenaline rush, a sudden burst of energy that seems to take over your body. Note: Norepinephrine plays a really big role in moods by keeping our moods stable (from getÝng too high or too low). c. Serotonin: responsible for emotional states, impulse control, and dreaming. Note: Serotonin plays a major role in stabilizing our moods, relative to our own sense. d. Dopamine: responsible for motivation and reward (maintain the spotlight). Note: Dopamine is critical for attention. Note: ADHD is the result of not having enough dopamine in the system (the mesolimbic system). e. GABA and Glutamate: GABA is involved in anxious states and glutamate aids learning and memory. Note: Glutamate creates excitation, it increases the likelihood of an action potential in the post narcotic neuron. Note: GABA inhibits or brings down the exploitation in a neuron and decreases the likelihood that that neuron can generate a new action potential. f. Endorphins: involved in reward and pain reduction. Note: Endorphins create analgesia, keeping us from being in constant pain. Note: Endorphins are responsible for pleasure as well. DRUGS - A drug is any molecule that starts outside of the body that, if it gets inside, causes a change. - All psychotropic drugs work by targeting different neurotransmitter systems, they alter the function of them. It causes change in behavior, thoughts, or emotions. a. Agonists: increases the activity in a neurotransmitter system. b. Antagonists: decreases the activity in a neurotransmitter system. - Drug effects have led to several discoveries about brain chemistry. 1. Stimulants: increases activity in the central nervous system (agonists in the dopamine, norepinephrine, and acetylcholine systems). Examples are nicotine, caffeine, cocaine, meth, amphetamines, and Adderall. 2. Depressants: decreases activity in the central nervous system (agonists in the GABA system and antagonists in the glutamate system). Examples are alcohol, Xanax, and Nembutal. 3. Narcotics: decreases pain and produces pleasurable things (agonists in the endogenous opioid system). Examples are opium, morphine, heroin, hydrocodone, oxycodone, and fentanyl. 4. Hallucinogens: alters perceptions, thoughts, and moods (agonists in the serotonin and the endocannabinoid system). Examples are ayahuasca, MDMA, CJD, peyote, LSD, DLT, psilocybin, and marijuana. - Addiction is formed when it becomes something that is part of your routine. It begins with repeated use of addictive things like cigarettes, cocaine, etc. a. Tolerance: when you need more of the drug in order to get the same effect Note: Your body adjusting to the drug and it becomes a new normal. b. Withdrawal: when you experience the symptoms that are always the exact opposite of the drug. c. Sensitization: when you behave the opposite of tolerance (side effects). Note: The effect of the drug keeps increasing, which affects behaviors, cognitive, emotion, and psychological. - The factors that influence development of addiction are environment and genetics (personal and physiological responses). THE DEVELOPMENT OF BRAIN - Phrenology was the practice of evaluating personality traits and mental abilities by measuring bumps on the human skull, used devices called psychographs. - The first method developed was a way to record the electrical activity of neurons firing in the brain, used a devices called the electroencephalograph. The practice is useful because different behavioral states produce different and predictable EEG patterns. - The brain’s electrical activity is associated with the flow of blood carrying oxygen and nutrients to the active location of the brain. The functional magnetic resonance imaging is used to measure changes in the level of blood’s oxygen and is able to map the working brain. The transcranial magnetic stimulation is used to temporarily disrupt activity in a specific location of the brain. The two parts of the CNS: the spinal cord and the brain. Meanwhile, the three main divisions of the brain: the hindbrain, the midbrain, and the forebrain, which each is associated with specific mental processes and behaviors. THE HINDBRAIN AND MIDBRAIN - The spinal cord is the bridge between the brain and the body, carrying sensory information up to the brain and motor signals from the brain to the body. It also coordinates reflexes. - Two distinct tissue types in the spinal cord 1. Gray matter: dominated by the cell bodies of neurons 2. White matter: consists mostly of axons and myelin sheaths to transfer messages in both spine and brain - The hindbrain contains forms which control body functions that are essential for survival. - Main structures of the hindbrain: a. The medulla: controls the most basic functions of survival (heart rate, breathing, etc) b. The cerebellum: is essential for proper motor function, such as motor learning and motor memory c. The pons: plays an important role in sleep, arousal, and coordinating movements between the left and right sides (includes dreaming) - The midbrain consists of several forms which are involved in the reflexive movement of the eyes and the body. It is critical for the production of dopamine. a. Reticular formation: controls arousal b. Substantia nigra: produces dopamine and generates movements and motivations. FOREBRAIN SUBCORTICAL STRUCTURES - The forebrain includes the cerebral cortex and several subcortical structures. - Four subcortical structures that are part of the limbic system Note: The limbic system serves as the border between the hindbrain and the midbrain, and the cerebral cortex, and is important for controlling motivated behaviors and emotions, and for forming memories. a. Thalamus: the sensory gateway to the cortex, which receives almost all incoming sensory information. Note: Thalamus is for sight, sound, touch, and taste. b. Hypothalamus: the brain’s master regulatory structure, which receives input from almost everywhere in the body and sends its influence to the body and brain, affects the functions of internal organs, and is involved in the motivations for behaviors. Note: In other words, hypothalamus regulates body functions and motivates behaviors. It’s in charge to do survival things (eat, stay warm, sex, etc). c. Hippocampus: is critical in the formation of new memories by creating new neural connections within the cerebral cortex for each new experience, and helps navigate in environments. d. Amygdala: to associate memory processing with emotional responses and is involved in learning about stimuli FOREBRAIN CEREBRAL CORTEX - The cerebral cortex is the place of your thoughts, perceptions, and behaviors. The cortex is divided into the left hemisphere and the right hemisphere. - Four areas, which are called lobes, of each cerebral hemisphere a. The occipital lobes: are important to vision and include many distinct visual areas Note: The largest are is the primary visual cortex, which is a processor of visual information, such as colors, forms, and motions b. The parietal lobes: are devoted to touch, which is directed to the primary somatosensory cortex c. The temporal lobes: are responsible for hearing and include visual areas specific for recognizing detailed objects (like faces) Note: These lobes hold the primary auditory cortex and at the intersection of the temporal and occipital is the fusiform face area d. The frontal lobes: are essential for complex thought, planning, and movement, with the rear portion of them is the primary motor cortex o The prefrontal cortex is critical for rational thought and the ability to follow social norms. Note: it provides us to understand what other people are thinking, connect with them emotionally, emphasize with them, and feel guilty about harming them. - The hemispheres are connected by a structure called the corpus callosum, which lets information flow between the left and the right hemispheres. - The left hemisphere is responsible for logical thought and language, and being able to speak and write. Meanwhile, the right hemisphere is responsible for spatial relationships, recognizing faces, understanding emotional aspects of language, and abstract thinking. SOMATIC NERVOUS SYSTEM - The somatic nervous system is part of the PNS that transfers signals to and from the CNS through nerves. The CNS sends signals to muscles, joints, and skin to initiate or inhibit movement. It controls all voluntary movements of skeletal muscles. - For each reflex action, a handful of neurons simply convert sensation into action based on processing only within the spinal cord. AUTONOMIC NERVOUS SYSTEM - The autonomic nervous system regulates the body’s internal environment by stimulating glands and maintaining internal organs. It controls physiological arousal. - - The autonomic nervous system has two subdivisions: the sympathetic nervous system and the parasympathetic nervous system. They provide signals which travel from the CNS to the organs and glands and back again. Preparations for action are prompted by the sympathetic nervous system, while returning to a normal state is a result from processing by the parasympathetic nervous system. ENDOCRINE SYSTEM - The endocrine system is a communication network which affects many aspects of the body. The nervous system and the endocrine system work together to control psychological activity. - The main difference between the two systems is in their forms of communication.  The nervous system = uses very fast electrochemical signals when neurons release neurotransmitters  The endocrine system = uses a slower method when chemicals are released from glands - Hormones are chemical particles that are released into the bloodstream by endocrine glands, until they reach their target tissues. Their effects can last for a long time and affect multiple body regions. - The endocrine glands include the pineal gland, the adrenal glands, the pituitary gland, the thyroid, and the testes or ovaries. - The main endocrine glands affecting sexual behavior are the gonads, which are the sex glands used for reproduction. Gonadal hormones influence the development of secondary sex characteristics and adult sexual behavior. - Growth hormone prompts bone, cartilage, and muscle tissue to grow or helps them regenerate after injury. GENES’ INFLUENCES - Genes control our physical characteristics, predispositions to particular diseases, and mental activities (personality, intelligence, etc). - Environment affects how genes are expressed and how it influences brain, mental activity, and behavior. - Genes make up genotype, which is set at the moment of conception and never changes. Meanwhile, observable physical and psychological characteristics are called phenotype. INTERACTION BETWEEN GENES AND ENVIRONMENT - The study of how genes and environment interact to influence mental activity and behavior is known as behavioral genetics. - Twin studies compare similarities between different types of twins to determine the genetic basis of specific traits. - Monozygotic twins are identical, while dizygotic twins are fraternal twins. - The increased similarity in the trait for monozygotic twins is considered most likely due to genotypes. - - Similarities among adopted siblings who are not biologically related have more to do with environment than with genes. Biological identical twins, whether raised together or not, were likely to be similar. Epigenetics is when the environment is seen as layered over genes. Various environmental exposures do not alter the genes themselves but how or when those are expressed. These changes can be passed along to future generations. ENVIRONMENT CHANGES THE BRAIN - Nurture can influence nature. Despite the great precision and the specificity of connections between neurons, the brain is extremely adaptable. - Plasticity reflects the interactive nature of biological and environmental influences. - The brain can change in three ways, which is growing new neurons, changing existing neural connections, and reorganizing. - The brain can grow new connections among neurons and grow new neurons. The production of new neurons is called neurogenesis. - When neurons activates another, the connection between them strengthens. The strengthened connection makes neurons more likely to fire together in the future. - Entirely new connections develop between nearly brain regions. If the cortex is injured, the surrounding gray matter assumes the function of the damaged area.