* Chemicals (hormones) * Slow and is carried by the bloodstream
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Nervous System
* A series of electrical impulses * Rapid and is carried by nerves
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What is the purpose of the endocrine and nervous system?
Increase/decrease body activities to maintain homeostasis
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Central Nervous System (CNS)
Brain and Spinal Cord
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Peripheral Nervous System (PNS)
Nerves connecting CNS to other body parts
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Autonomic Nervous System
Division of the PNS that controls automatic body functions
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Somatic Nervous System
Division of the PNS that control voluntary body functions
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Dendrites
* Branches of the neuron that receive input (stimulus) * “__________ Listen” * Can be hundreds per neuron * Send nerve impulses __toward cell body__
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Cell Body (Soma)
* Contains nucleus and organelles * Cytoplasm, mitochondria, etc.
* Send impulses __away from cell body__ * “________ Speak” * One axon per neuron * Terminal Branches
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Myelin Sheath
* White matter surrounding parts of axon (not the dendrites or cell body) * Consists of lipids, proteins, water * Insulates axon and increases impulse speed
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When does myelination begin in human?
During the third trimester
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Nodes of Ranvier
* Gaps in myelin sheath * Allows impulse to travel faster * Impulse “jumps” from node to node
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Neurons
* Nerve cells * Transmit impulses
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Sensory/Afferent Neurons
* Impulses to the CNS * **“**__**A**__rriving at the CNS”
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Motor/Efferent Neurons
* Impulse away from the CNS * “__**E**__xiting the CNS”
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Interneurons
Neurons found in CNS that connect two sections of the brain
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Glia Cells
* “Glue” * Don’t transmit impulses * Provide structural support and nutrient
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Microglia
A type of glia cells that are the immune system of the CNS (microbe eater)
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What causes Multiple Sclerosis?
* Microglia eat away at myelin causing a bumpy transmission of impulse * Driving on a road with potholes
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Oligodendrocytes
* Glia cell that produces myelin in the CNS * One cell that branches out to myelinate many axons
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Schwann Cells
* Produce myelin in PNS * Only found on individual axons * Not branched
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Astrocytes
* Star Cells * Keep neurons near blood supply (access to nutrients) * Make up the Blood Brain Barrier
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Glioma
* Most common type of brain tumor * Tumor of a glia cell
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Action Potential
* Nerve impulse that travels along the axon
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When a neuron is at rest it is…
* Positive outside and negative inside * Polarized * Excess of Na+ on the outside
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Explain a nerve impulse
* Stimulus at dendrites triggers the opening of Na+ channels * Na+ rushes in and depolarizes the membrane (inside is more positive than the outside at stimulated point) * This then travels down the neuron and the impulse is complete
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Saltatory Conduction
* Impulse jumps from one Node of Ranvier to the next * Latin for jump * Much faster than impulse in non-myelinated section
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Synapse
The place where impulses are transmitted from one neuron to another