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Psychology Day 7.docx

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Wilfrid Laurier University
Lawrence Murphy

Psychology Day 7 Chapter 4 Lecture: Monday, October 1 The Brain: Source of Mind and Self The Nervous System  Two main parts: o Central nervous System (CNS)- receives, processes, interprets and stores incoming sensory information  Sends out messages to muscles gland and organs o Peripheral nervous system (PNS)- handles input and output from the CNS  All portions of the nervous system outside the brain and spinal cord  Central nervous system o Spinal cord- is a bridge between the brain and parts of the body below the neck o Spinal nerves protected by the spinal column o Enables spinal reflexes  Peripheral nervous system o Contains two subdivisions (messages carried through sensory and motor nerves)  Somatic Nervous System- nerves connected to sensory receptors and skeletal muscles  Autonomic nervous system- regulates functions of blood vessels, glands and internal organs  Contains two systems: Parasympathetic and Sympathetic o Parasympathetic- to conserve bodily functions (decreased heart rate, decreased respiration, pupils constricted) o Sympathetic- mobilize or flee (heart races, goosebumps, sweats, pupils dilate, increased respiration) Communications in the Nervous System  Nervous system made up of: o Neurons- cells that conduct electrochemical signals; basic unit of the nervous system  Combination of shock telling cell to release a chemical which inhibits a reaction from the brain o Glia- cells that support, nurture and insulate neurons, remove debris when neurons die, enhance the formation and maintenance of neural connections, and modify neural functioning  Almost the glue that holds the cells together  Structure of the neuron: o Approximately 100 billion neurons in the brain o Neurons vary in size and shape o Electrical signal goes down the dendrites and along the axon which is received by the synapse and if it is strong enough the cell will release the chemical o Dendrites- branch-like fibres that receive information from other neurons and transmit towards cell body o Cell body- keeps neuron alive and plays key role in determining whether neuron will “fire” o Axon- extending fibre that conducts impulse away from cell body and transmits to other cells  Branches at the end called axon terminals  May be collected together in bundles called nerves o The myelin sheath- many axons are insulated by surrounding layer of fatty materials called myelin sheath  In the CNS, this is made up of glial cells  Constrictions in covering (nodes) divide myelin into segments  Purpose to speed conduction of neural impulses and prevent interference from neighbouring signals Neurons in the News  Neurogenesis- production of new neurons from immature stem cells o Controversial because you need stem cells from embryos  Stem cells: o Immature cells that renew themselves and have potential to develop into mature cells o Stem cells from early embryos can develop into any cell type o Hold the potential to cure pretty much any disease, illness or even injuries Stem-Cell Research  Embryonic stem cells can differentiate into any type of cell; adult stem cells limited o Use is controversial and surrounded by ethical debates regarding extractions and when the embryo is technically living o Most promising in developing treatments for cancer, blood, organ and brain disorders (Alzheimer’s) o Canadian researchers have had some success with adult stem cells transforming to brain cells How Neurons communicate  No direct contact between neurons  Communicate through synapse o Includes the axon terminal, symnaptic cleft, and receptor sites in the membrane of the receiving cells o This is what happens when a person is on drugs, the chemicals in the drug mimic that of a chemical from the brain and reacts on the receptor sites on the receiving cell  Communication occurs through electrical and chemical signals o Stimulation causes charge between, inside and outside the cell o Inflow of sodium ions causes an action potential- the electric signal o Synaptic vesicles release chemicals called neurotransmitters  Neurotransmitters bind to receptor sites on receiving neuron and causes changes in the cell membrane o Excitatory changes- a voltage shift in a positive direction  Increases probability of receiving neuron firing o Inhibitory changes- a voltage shift in the negative direction  Decreases probability of receiving neuron firing  Consider alcohol causing you to pass out or die this is an inhibitory reaction Brain Plasticity  Plasticity: o The brains ability to change and adapt in response to experience (recognizing or growing new neural connections) o Behavioural deficits that occur as a result of brain damage may be lessened by enriching the environments people live in Chemical Messengers  Neurotransmitters: o A chemical substance that is released by a transmitting neuron at the synapse and that alters the activity of receiving neuron  Major neurotransmitters: o Serotonin, dopamine, acetylcholine, norepinephrine, GABA, glutamate  Each neurotransmitter has different effects: o Serotonin: sleep, appetite, sensory perception, temperature regulation, pain suppression, mood o Dopamine: voluntary movement, learning, memory, emotion, pleasure or reward, response to novelty  This is what makes drugs addictive by hijacking the reward centre of the brain o Acetylcholine: muscle action, cognitive functioning, memory and emotion o Norepinephrine: increases heart rate, slowed intestinal activity during stress, learning, memory, dreaming, waking, emotion o GABA: major inhibitory neurotransmitter  Inhibits your body’s ability to say no o Glutamate: major excitatory neurotransmitter in the brain o Endorphins:  Chemical substances in the nervous system that are similar in structure and action to opiates  Involved in pain reduction, pleasure and memory  Technically known as endogenous o Hormones:  Chemical substances, secreted by organs called endocrine glands, that affect the functioning of other organs  Regulate growth, metabolism, sexual development and behaviour  Major hormones:  Melatocin- regulate daily biological rhythms (sleep)  Oxytocin- childbirth contraction, milk ejection  Adrenal hormones- emotion, stress, epinephrine  Sex hormones- androgens and estrogens Psychology Day 11 Lecture Monday, October 22 Chapter 5 Body Rhythms and Mental States Biological Rhythms  A periodic, more or less regular fluctuation in a biological system o Hormones o Temperature in the body  Rhythms can be synchronized with external (entrainment) or internal cues (endogenous)  Biological rhythms influence effectiveness of medication, alertness, job performance Circadian Rhythm  Circadian rhythm occur approximately every 24 hours (e.g. sleep-wake cycle) o Commonly entrained to external time cues o Endogenous rhythms averages around 24.3 hours  When you take away all the external cues (alarms etc.) and put people in a cave the average endogenous is 24.3 hours of sleep o Removed from cues about 10% of people have clocks running lower and 10% running faster o Increase in accidents at transition to Daylight Savings Time o Controlled by biological clock in suprachiasmatic nucleus (SCN)  Regulates levels of Melatonin secreted by pineal gland Out of Sync?  Internal de-synchronization o A state in which biological rhythms are not in phase (synchronized) with one another o Changes I your normal routines can cause de-synchronization o May also occur in response to jet lag, rotating shift work, daylight savings time Moods and Long-Term Rhythms  Seasonal Affective Disorder (SAD) o A disorder in which a person experiences depression during the winter and an improvement of mood in the spring o Treatments may involve phototherapy or exposure to fluorescent light o Inconsistent findings with respect to prevalence (2-20%) and effectiveness of treatments o Not a form of de-synchronization Moods and Menstrual Cycles  Premenstrual Syndrome (PMS) o Vague cluster of physical and emotional symptoms associated with the days preceding menstruation that was labeled as an “illness” o Physical symptoms (e.g., cramps, water retention are common) o Emotional symptoms (e.g., irritability, depression) are rare. Moods, PMS and Research  Estimates of prevalence range from 13% to “most women”  Expectations and beliefs may be related to PMS Symptom reporting  Evidence supports that women often experience physical symptoms but emotional symptoms are relatively rare  Recent research……… The Rhythms of Sleep  During sleep, we cycle between periods of REM and non-REM sleep (~90 minutes) o Rapid Eye Movement (REM) – characterized by eye movement, loss of muscle tone, and dreaming o Non REM (NREM) sleep – characterized by fewer eye movements then REM The stages of Sleep  Stage 1 o Feel on the edge of consciousness; light sleep  Stage 2 o Presence of sleep spindle; minor noises wont disturb you  Stage 3 o Delta waves begin; breathing and pulse have slowed down; hard to awaken  Stage 4 o Delta waves predominant; deep sleep; most likely stage for sleepwalking  Rapid eye movement (REM) sleep: increased eye movement, loss of muscle tone and dreaming, this is where most of the dreaming happens Why we sleep  Exact function of sleep unclear…  But allows for certain processes to occur o Body eliminates waste products from muscles o Cells are rep
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