Maggie O’Connor Zimmy Tran April 11, 2013
Nerve Cell Neuron Composed of billions of neurons The main portion is called the soma or cell body 1 Cell body contains nucleus
Neuron Dendrites Chemical messages from other neurons Axon- longer than dendrites Extension different from the branch like dendrites
Axon
Main job- to transmit an electro-chemical signal to other neurons Send signals from spinal cord to toes Three feet in length
Axon Covered in myelin sheath Myelin sheath-fatty cells wrap around an axon multiple times They cover and protect Insulator for the electric wire
Axon Axon ending Electro-chemical signal reaches the axon ending Travels length of neuron Converts electro- chemicals into chemical message Sends to another neuron Axon Ending
How A Neuron Works Balance of ions are changed Effect of the change in ions runs through the cell membrane to the axon Reaches the axon Begins action potential which is a rapidly moving exchange of ions Action potential is a pulse of electricity milivolts Forms tiny bubbles called vesicles
Neuron Signal reaches the axon ending Transmitted to a neighboring nerve cell through the chemical neurotransmitter Neurotransmitters go into the synapse to the next neuron Find places on the neuron called receptor sites Change the balance of ions Neurotransmitter tells the neuron what to do next Process repeats
Embryonic Stem Cells Found in the embryo Embryo is a ball of about 100 cells when it is a couple of days old Blastocyst
Blastocyst has an outer layer called trophectoderm Trophectderm forms the placenta Supports the embryo inside the uterus Inner mass cells are a clump of cells
Blastocyst Unspecialized Multiply and differentiate form different cells animal cells need Pluripotent can make every type of cell in the body
Proliferation First process of a neuron forming from an embryo Increases the number of cells in early development of embryo Begins closing of the neural tube is completed
Determination Determination- Destiny of certain cells is decided. Become the precursors Give rise to many types of neurons and glial cells Glial cell- type of cell in the human nervous system
Differentiation Third process Given population of neurons rise to subpopulation Specific to parts of the nervous system. Continue to proliferate Move to their final locations. Specific connections with other neurons
Stem Cells Pluripotent stem cells form in primary germ layers Germ layers: ectoderm, endoderm, and mesoderm Ectoderm-The nervous system
Ectoderm Outmost most layer Three separate layers: the external ectoderm, the neural crest, and the neural tube. The neural crest- located between the external ectoderm and the neural tube. Contains tissues become neurons Neural crest-precursor to the central nervous system The brain
Sources THE BRAIN FROM TOP TO BOTTOM. (n.d.). Le cerveau à tous les niveaux. Retrieved April 10, 2013, from ev/d_09_cl_dev.html Lecture - Ectoderm Development - Embryology. (n.d.). Retrieved from Lecture_-_Ectoderm_Development The Neuron. (n.d.). Retrieved from