Neuron Structure PDF

Neuron Structure  Divisions of the Nervous System ▪ Two Divisions: 1. Structural Divisions ▪ Central Nervous system (CNS) ▪ Peripheral Nervous system (PNS) 2. Functional Divisions ▪ Sensory ▪ Motor Structural Divisions ▪ Central Nervous System (CNS) ▪ B...

Neuron Structure  Divisions of the Nervous System ▪ Two Divisions: 1. Structural Divisions ▪ Central Nervous system (CNS) ▪ Peripheral Nervous system (PNS) 2. Functional Divisions ▪ Sensory ▪ Motor Structural Divisions ▪ Central Nervous System (CNS) ▪ Brain ▪ Spinal Cord ▪ Peripheral Nervous System (PNS) ▪ All nervous tissue outside the CNS ▪ Cranial Nerves - 12 Pains ▪ Spinal Nerves -31 Pairs ▪ Receptors - monitor environment ▪ Ganglia- group of cell bodies ▪ Nerve Plexuses - bundle of nerves  Functional Divisions of PNS 5 special senses. CNs > effector equalibrium Take Info · - · commands to Skeletal receptors · somatic - · skin muscles - aka movement Info CNS organs > -> cardiac muscle. - commands to · smooth muscles - glands  Histology of Nervous Tissue 1. Neurons *▪ Excitable cells ▪ Send electrical signals known as action potentials 2. Neuroglia ▪ Support tissue for the nervous system Neuron Structure  Neuron Components ▪ Cell Body (Soma) ▪ Contains the nucleus and other organelles ▪ Perikaryon - area around ur nucleus that contains organelles. ▪ Nissl Bodies – Free ribosomes and rough ER filaments. ▪ Neurofibrils - intermediate - structural support. * no centrioles ↳. no cell division Limits nervous tissue repair.  Neuron Components ▪ Dendrites ▪ Branches off the cell body a neuron to receive Input allows other neurons Recieves Input from · · Will transmit graded potential ▪ Will transmit graded potentials D ▪ More dendrites = more input  Neuron Components ▪ Axon ▪ Processes that can transmit action potentials ▪ Components: ▪ Trigger Zone - start of the axon (where action potential begins) ▪ Axolemma Lemma (membrane axon's cell membrane ▪ Axoplasm Axon's Cytoplasm ▪ Axon Collaterals branched of axon  Neuron Components ▪ Telodendria ▪ Extensions of the axon ▪ Terminate at axon terminals information to another cell or neuron Distributes · Neuron Info in via dendrites Information travels neuron → neuron · Travels as action potential info comes in via dendrites ↳ Info out comes via axon terminals. Presynaptic neuron → works via synapses. Postsynaptic neuron → Info out via axon terminals  Basic Synapse Structure ▪ Presynaptic Neuron ▪ Ends in an axon terminal or synaptic knob ▪ Often contain synaptic vesicles ▪ Presynaptic membrane · contains various neurotransmitters ↳ dopamine, Seratonin i etc. ▪ Synaptic Cleft space between presynaptic + postsynaptic cells ▪ Postsynaptic Neuron ▪ Can be another cell or another neuron ▪ Postsynaptic membrane ▪ Often contains receptor sites have receptors for neurotransmitters.  Unmyelinated Axons · rest in depressions of the axons Schwann cell or oligodendrocyte axon surrounded is not completly ·  Myelinated Axons cell or oligodendrocyte wraps · Schwann around a segmen of an axon forming multiple layers , in the mylin sheath. These layers are  myelin Forms myelin Myelination · Forms sheath in Sheath in PNS CNS The Myelin Sheath ▪ Myelin Sheath ▪ Has a high lipid content Insulate axon · Rapid · action potential propagation (speed ▪ Internodes areas contain myelin ▪ Nodes of Ranvier Gaps In the myelination ▪ White Matter myelinated axons high lipids amount make it white in color ▪ Gray Matter · myelinated axons and neur on cell bodies,