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Overview of the Day. Neuroscience, Part 1 Neural Systems Hormonal Systems. The Nervous System. Provides the biological substrate for psychological activity (the body's fast communication system consisting of all the nerve cells in the central and peripheral nervous systems). Major Parts.
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Overview of the Day Neuroscience, Part 1 Neural Systems Hormonal Systems
The Nervous System • Provides the biological substrate for psychological activity (the body's fast communication system consisting of all the nerve cells in the central and peripheral nervous systems)
Major Parts • Central Nervous System (brain and spinal cord) the system that enables our humanity--thinking, feeling acting • spinal cord (info. highway connecting PNS to brain) • brain (receives info., interprets it, and decides what to do) • Peripheral Nervous System (carries info. to and from the CNS) • somatic/skeletal nervous system (controls voluntary movement of skeletal muscles • autonomic nervous system (controls glands and muscles of internal organs [e.g., heart]). The sympathetic and parasympathetic systems work together to keep us in a steady internal state • sympathetic: readies body in response to threat • parasympathetic: calms body; conserves energy
Nerves • cables, made up of millions of bundles of neurons, that are part of the PNS, and which connect the CNS with muscles, glands, and sense organs
Example: Bee Sting • Stinger in your finger --> • PNS--> • Spinal cord--> • Brain--> • Spinal cord--> • PNS-->vocal muscles (ouch!!) & arm and hand (swat bee)
Building Blocks • Neurons--the basic unit of the nervous system • approximately 10 - 100 billion of them in human body • speed of neural transmissions range from 2 to 200 mph • Parts of neurons • dendrites (receive information) • axon (passes info. along to other neurons or muscles or glands) • terminal branches of axon (forms junctions with other cells) • myelin sheath (insulates axons and helps speed their impulses) • Neural Networks • neurons in brain cluster into work groups called neural networks; learning occurs as feedback strengthens connections that produce certain results
How Neurons Work • Action potential • neuron fires an impulse (action potential) when it is stimulated by pressure, heat, light, or chemical messages from other neurons • Threshold • if the excitatory impulses a neuron receives are greater than inhibitory impulses exceeds a minimum intensity, called a threshold, then neuron transmits an electrical impulse (action potential) down its axon to other neurons • threshold is all or nothing. • then how can we detect differences in intensity (soft vs. loud music)? • more neurons fire when intensity is greater
Neurotransmitters • chemical messengers that allow neurons to communicate with one another • between neurons is a small space (1 millionth of an inch thick) called synaptic cleft • when action potential reaches knob-like terminals at axon's end, it triggers release of neurotransmitter • they cross synaptic cleft and bind to receptor cites on dendrites of next neuron: receptor cites are specific to each type of neurotransmitter
Common Neurotransmitters • Acetylcholine - neurotransmitter that is at every junction between a motor neuron and muscle • curare a poison that causes paralysis: blocks Ach receptor sites, leaving neurotransmitter unable to affect muscles • Endorphins -released in response to pain or vigorous exercise • responsible for “runner’s high” • Serotonin - affects mood • antidepressant drugs alter production or transmission of serotonin
Endocrine System • Secretes hormones, chemical messengers, that travel through the bloodstream and affect other tissues and brain • Non-specific and slower than CNS and PNS • difference between nervous system and endocrine system: cell phone in football game vs. PA announcement
Summary • Nervous system (CNS, PNS) • Neurons (parts, how they work) • Neurotransmitters • Endocrine system