M. AshcraftPYSCH 1105: CHAPTER 2 BIOLOGY OF THE MINDINTRODUCTIONo Psychological and biological processes and inherently intertwinedo Phrenology A popular but ill-fated theory that bumps on the head could predict character traits and mental abilities Corrected focused the idea that certain brain regions have certain functions o Recent discoveries made by biologists Body is composed of cells Among these cells are nerve cells that conduct electrical current and send signals to each other through the tiny gaps between them Specific regions have specific functions within the brain We use these regions to integrate information and conduct our experience of sight, pain, etc Our adaptive brain is wired through experience Biological scientists: scientists that study the link between psychcology and biology- Tissues are composed of specialized cells that make up our individualNUERAL INTEGRATIONo Nuerons Basic building blocks of the nervous system Types:- Sensory neurons: carry information to the central nervous system- Motor (efferent) neurons: carry information from the CNS to the rest of the body- Interneuron: located in the CNS, intergrate the information, responsible for the nervous systems complexity (most abundant) Components:- Dendrite: receiving extensions attached to the soma- Soma: cell body - Axon: conduct signal away from the cell body - Myelin Sheath: a layer of fatty tissue that surrounds the axon and provided electrical insulationo Degeneration results in multiple sclerosis Transmission:- Triggered by chemicals from neighboring neurons or from our senses- Action Potentialo A brief electrical charge that travels down an axono Generated by the movement of positively charged ions travelling in and out of channels on the axon- Threshold: Each neuron receives excitatory and inhibitory signals from many neurons. When the excitatory signals minus the inhibitory signals exceed a minimum intensity (threshold) the neuron fires an action potential.- Generate signals like batteries through chemical signals - Converts chemistry to electricity through the interaction of ionso Resting potential: negative charge inside, positive charge outside Charge maintained by selectively permeable membrane of the axon- At the axon hillock: the gates open allowing positive ions to rush indepolarizingo This activates gates further down on the axon, generating an action potentialo During the refractory period, the cell pumps the sodium ions back outside- Integration:o Make decisions based on impulse from excitatory and inhibitory impulseso If exceed a certain level (threshold) an AP will result Action potential PropertiesM. Ashcraft- All-or-none: A strong stimulus can trigger more neurons to fire, and to fire more often, but it does not affect the action potentials strength or speed.- Intensity: of an action potential remains the same throughout the length of the axon.o Nueral Communication Synapse- Causes a pause in transmission- A gap between the axon tip of the sending neuron and the dendrite or soma of the receiving Nuerotransmitters- When the signal reaches the axon tip, it stimulates the release of chemicals from the axon- These chemicals are called neurotransmitters- Travel across the cleft and bind to specific receptor sites on the receiving neuron- This causes gates to open on the receiving cell that can inhibit or excite a neuron- Influence ability to create an AP Reuptake: the remaining neurotransmitters are reabsorbed - Prevents overstimulationNeurotransmitter Function DiseaseAcetylcholine (Ach) Neuromuscular junction, learning and memory Alzheimer’s: Ach producing neurons deteriorate, if receptors are blocked, then brief anesthesia results Dopamine Influences learning, movement, attention and emotionExcess dopamine receptor activity is linked to schizophrenia. Starved of dopamine, the brain produces the tremors and decreased mobility of Parkinson’s disease.Serotonin Effects mood, hunger, sleep, and arousalUndersupply linked to depression. Prozac and some other antidepressant drugs raise serotonin levels.Norepinephrine Control of alertness and arousalUndersupply can suppress moodGABA Major Inhibitory Undersupply linked to seizures, tremors and insomniaGlutamate Major excitatory, memory functionsOversupply can overstimulate brain, produc- ing migraines orseizures (which is why some people avoid MSG, monosodium glu- tamate, in food).- Candance Pert and Soloman Snyder o Discovered through opiate study that we have endorphins (linked to pain control and pleasure) o Which are enhanced through exercise “runner’s high” and acupuncture- Drugs and chemicals influenceo Do not flood the brain with opiates because the brain will stop making endorphinso Many chemicals amplify or inhibit the effect of neurotransmitters (lock and key mechanism) Agonist: a chemical similar enough to the neurotransmitter to use its receptor and mimic its effects- Ex: opiates from drugs fill the receptors of endorphinsM. Ashcraft Antagonists: block a nuerotransmitter’s functioning- Ex: botulism binds to Ach receptorsparalysisNERVOUS SYSTEM- Kinds of Neuronso Sensory: rely from receptors the brain (bipolar)o Motor: from CNS to target (multipolar)o Internueron: intergrating center (unipolar)- Central Nervous System (CNS)o The brain and the spinal cord- Peripheral Nervous System (PNS)o Glands, muscles, and sensory receptorso 2 sections: Somatic and Motor Somatic: enables movement of our skeletal muscles Automatic: controls glands and visceral organs- functions like control of HB and digestion- Sympathetic Nervous Systemo Arouses and expends energyo Flight or fight responseo Directs energy from digestion to skeletal muscles, and vasodilates in skino Increases heart rate - Parasympathetic Nerous Systemo Resting and Digesting - Nerveso Bundles of axons that enable the CNS and PNS connectionTHE BRAIN- Electrocardiogram (EEG)o An amplified recording of electrical activity across the brain surface measured by electrodes placed on the scalp- Neuroimaging Techniqueso PET scan (positron emission tomography) A visual of brain activity that detects a radioactive form of glucose while the brain performs a task Shows the chemical consumption of certain regions of the braino MRI (magnetic resonance imaging) Uses magnetic and radio waves to produce computer generated images that distinguish amongst different types of brain tissue Rapidly images the
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