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Neural and Hormonal Systems Module 3 1 Neuroscience and Behavior Overview Neural Communication Neurons How Neurons Communicate How Neurotransmitters Influence Us The Nervous System The Peripheral Nervous System The Central Nervous System The Endocrine System 2 History of Mind Phrenology In 1800, Franz Gall suggested that bumps of the skull represented mental abilities. Bettman/ Corbis 3 Neural Communication Neurobiologists and other investigators understand that humans and animals operate similarly when processing information. 4 Neural Communication The body’s information system is built from billions of interconnected cells called neurons. A nerve cell, or a neuron, consists of many different parts. 5 The cell body • Contains the cell’s Nucleus – Round, centrally located structure – Directs metabolism – No role in neural signaling 6 Dendrites • Information collectors • Receive inputs from neighboring neurons • If threshold is reached the AXON will generate an output 7 Dendritic Growth • Dendrites can form new connections • Provides room for more connections to other neurons • New connections are basis for learning! 8 Axon • The cell’s output structure • One axon per cell, 2 distinct parts – tubelike structure, terminal branches at end that connect to dendrites of other cells 9 Myelin sheath “Practice makes Myelin, Myelin makes perfect.” • Specialized Glial cells • Acts as an electrical insulator • Not present on all cells • Increases the speed of neural signals down the axon. Myelin Sheath Parts of a Neuron link .50 10 How neurons communicate • Neurons communicate by means of an electrical signal called the Action Potential • Action Potentials are based on movements of ions between the outside and inside of the cell • When an Action Potential occurs a molecular message is sent to neighboring neurons 12 13 Action Potential A neural impulse. A brief electrical charge that travels down an axon and is generated by the movement of positively charged atoms in and out of channels in the axon’s membrane. 14 15 Threshold Threshold: Each neuron receives excitatory and inhibitory signals from many neurons. 16 Action Potential Properties All-or-None Response: 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. 17 Synapse Synapse [SIN-aps] a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. 18 Neurotransmitters Neurotransmitters (chemicals) released from the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron. 19 Reuptake Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake. 20 Chemical Messengers • Neurotransmitters • Hormones • Neurohormones 21 Types of Neurotransmitters • • • • • • • Acetylcholine Serotonin Norepinephrine Dopamine Endorphins GABA Glutamate 22 Acetylcholine • Found in neuromuscular junction • Involved in muscle movements 23 Disruption of Ach Functioning • Curare - blocks ACh receptors – paralysis results • Nerve gases and Black Widow spider venom - too much ACh leads to severe muscle spasms and possible death • Cigarettes - nicotine works on ACh receptors – can artificially stimulate skeletal muscles, leading to slight, trembling movements 24 Alzheimer’s Disease • Deterioration of memory, reasoning, and language skills • Symptoms may be due to loss of ACh neurons 25 Serotonin Serotonin pathways are involved with mood regulation. LSD and Seratonin at Nat Geo 2:21 26 Dopamine Important for movement, rewards & pleasure. Involved with diseases such as schizophrenia and Parkinson’s disease. Link dopamine flood at Nat Geo 3:4427 Parkinson’s Disease • Results from loss of dopamine-producing neurons • Symptoms include – – – – – difficulty starting and stopping voluntary movements tremors at rest stooped posture rigidity poor balance 28 Parkinson’s Disease • Treatments – L-dopa – transplants of fetal dopamine-producing substantia nigra cells – adrenal gland transplants – electrical stimulation of the thalamus has been used to stop tremors 29 Oliver Sacks: “Awakenings” • Patients had suffered from encephalitis lethargica decades earlier • Patients were in a frozen or semi-frozen state • Encephalitis lethargica causes the symptoms of Parkinson’s disease 30 Sacks: Results L-Dopa Sacks administered the experimental drug L-Dopa • Patients “awoke” from their frozen states 31 Sacks: Results & Legacy • L-Dopa lost its effectiveness, and patients returned to their frozen state • The experiment showed the relationship between encephalitis lethargica and dopamine and between encephalitis lethargica and Parkinson’s disease 32 • Showed how medicine can affect behavior Norepinephrine • • • • • • Arousal Sympathetic nervous system “Fight or flight” response Wakefulness, sleep Learning Mood regulation 33 Endorphins • Control pain and pleasure • Released in response to pain • Morphine and codeine work on endorphin receptors Involved in healing effects of acupuncture • Link Endorphins at AM 5:12 34 Gamma-Aminobutyric Acid (GABA) • Main inhibitory neurotransmitter of the CNS when you sleep • Benzodiazepines (which include tranquilizers such as Valium) and alcohol work on GABA receptor complexes 35 Glutamate • Major excitatory neurotransmitter • Too much glutamate (and too little GABA) associated with epileptic seizures • Involved w/memory 36 Lock & Key Mechanism Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism. 37 Agonists 38 Antagonists 39 The Nervous System Overview 40 The Nervous System Nervous System: Consists of all the nerve cells. It is the body’s speedy, electrochemical communication system. Central Nervous System (CNS): the brain and spinal cord. Peripheral Nervous System (PNS): the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body. 41 Nervous System Central Nervous System (CNS) Peripheral Nervous System (PNS) 42 Kinds of Neurons Sensory Neurons carry incoming information from the sense receptors to the CNS. Motor Neurons carry outgoing information from the CNS to muscles and glands. Interneurons connect the two neurons. 43 Central Nervous System The Spinal Cord and Reflexes Simple Reflex 44 The Nerves Nerves consist of neural “cables” containing many axons. They are part of the peripheral nervous system and connect muscles, glands, and sense organs to the central nervous system. 45 Peripheral Nervous System (PNS) Somatic Nervous System: The division of the peripheral nervous system that controls the body’s skeletal muscles. Autonomic Nervous System: Part of the PNS that controls the glands and other muscles. 46 Autonomic Nervous System (ANS) Sympathetic Nervous System: Division of the ANS that arouses the body, mobilizing its energy in stressful situations. Parasympathetic Nervous System: Division of the ANS that calms the body, conserving its energy. 47 Central Nervous System The Brain and Neural Networks Interconnected neurons form networks in the brain. Complex Neural Network 48 The Endocrine System The Endocrine System is the body’s “slow” chemical communication system. Communication is carried out by hormones synthesized by a set of glands. 49 Hormones vs. Neurotransmitters • Distance traveled between release and target sites • Speed of communication 50 Hormones Hormones are chemicals synthesized by the endocrine glands that are secreted in the bloodstream. Hormones affect the brain and many other tissues of the body. For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar, and feelings of excitement during emergency situations. 51 Pituitary Gland Is called the “master gland.” The anterior pituitary lobe releases hormones that regulate other glands. The posterior lobe regulates water and salt balance. 52 The effects of the pituitary are clearly shown here. Entertainer David Frost stands between the world’s tallest and smallest man. The tallest man in history was 8 feet 11 inches tall. He died at the age of 22, partly as a result of this defect. The shortest known person was 23 inches tall when she died at the age of 19. Today’s medicines can handle most of these problems if caught earlier enough, but these cases show what happen if the pituitary gland goes awry. 53 • Tallest man • http://www.youtube.com/watch?v=zL_nklb ytbY • Smallest man • http://www.youtube.com/watch?v=UyJOO S6raQw • Tallest woman • http://www.youtube.com/watch?v=F0V_8Z XZyzM • Gigantism at National Geographic 44:55 54 Adrenal Glands Adrenal glands consist of the adrenal medulla and the cortex. The medulla secretes hormones (epinephrine and norepinephrine) during stressful and emotional situations, while the adrenal cortex regulates salt and carbohydrate metabolism. 55 Endocrine Glands • Thyroid gland – metabolism, calcium • Pineal gland - sleep and wakefulness • Pancreas - regulates blood sugar level • Ovaries and testes - secrete sex hormones such as testosterone and estrogen 56 EXPLORING PSYCHOLOGY (7th Edition in Modules) David Myers PowerPoint Slides Aneeq Ahmad Henderson State University Worth Publishers, © 2008 57 • Altering neurons with light at ted talks 18:24 • Recording neuronal activity at ted talks 17:35 58 Neurotransmitter pathways 59