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Chapter 39

LIFESCI 2 Chapter Notes - Chapter 39: Axon Hillock, Schwann Cell, Potassium Channel

Life Sciences
Course Code
Esdin Joseph

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Chapter 39 Notes
Nervous System
o The nervous system is made of billions of neurons
o Neurons are able to communicate with each other and with other cells in the body
through electrical and chemical signals
o Soma:
Also known as perikaryon or cell body
5-140 micrometers in diameter
Abundant protein synthesis organelles
o Dendrites
Many extensions from cell bodies
Up to thousands in number in certain neurons
Receptive sites for electrical signal
o Axon hillock/Axon
A neuron has only one axon typically
Initial branching called axon hillock
Generate and conduct signals from soma
Abundant microtubules for transport
Also known as nerve fibers
Electrical signal always goes away from Soma
o Axon Terminals
Axon collaterals terminate in many axon terminals
Contain neurotransmitter filled vesicles
Neurotransmitters transmit message
o Myelin
Schwann cells produce myelin sheaths that insulate the axon
Nodes of Ranvier are gaps in myelin sheaths along the axon
Lipid sheath that insulates axon and speeds up electrical activity
Classification of Neurons
o Afferent neurons send information to the central nervous systems (CNS)
o Interneurons connect neurons within the CNS
o Efferent neurons send information from the CNS
o Classified:
Motor neurons
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