Overview of the Day

1. Overview of the Day Neuroscience, Part 1 Neural Systems Hormonal Systems

2. 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)

3. 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

4. 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

5. Example: Bee Sting • Stinger in your finger --> • PNS--> • Spinal cord--> • Brain--> • Spinal cord--> • PNS-->vocal muscles (ouch!!) & arm and hand (swat bee)

6. 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

7. 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

8. 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

9. 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

10. 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

11. Summary • Nervous system (CNS, PNS) • Neurons (parts, how they work) • Neurotransmitters • Endocrine system