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Describe the soma of a neuron.
Contains nucleus and most of the organelles.
Describe the dendrites of a neuron.
Reception of incoming information.
Describe the axon of a neuron.
Transmits electrical impulses called action potentials.
Describe the axon hillock of a neuron.
Where the axon originates and action potentials are initiated.
Describe the axon terminal of a neuron.
What is a synapse?
Site of communication between two neurons or between a neuron and an effector organ.
What are the three types of Ion channels found in neurons?
- Leak Channels
- Ligand-gated channels
- Voltage gated channels
Describe leak channels.
- They are always open.
- They are located throughout the neuron.
- These contribute to resting membrane potential.
Describe Ligand-gated channels.
- These open or close in response to ligand binding.
- These are found on dendrites and the cell body.
- These are responsible for synaptic potential.
Describe Voltage gated channels.
These open or close in response to change in membrane potential.
What are the two categories of Voltage gated channels?
- Sodium and potassium channels
- Calcium channels
Describe sodium and potassium voltage gated channels.
- These are located throughout the neuron, but are most concentrated at the axon hillock.
- These generate action potentials.
Describe calcium voltage gated channels.
- These are located at the Axon terminal.
- These are responsible for the release of a neurotransmitter.
List and describe the three structural classes of Neurons?
- Bipolar : Olfaction and Vision
- Pseudo-unipolar : Most sensory neurons
- Multipolar : Most common
What are the three functional classes of neurons?
Describe Afferent neurons.
- Transmits inpulses to the CNS for further processing.
- Transmits signals from sensory and viceral receptors.
- Mostly pseudo-unipolar neurons with the cell body located outside the CNS in a ganglion.
Describe Efferent neurons.
- These transmit signals from the CNS to effector organs.
- The cell body and the dendrites are located inside the CNS, except for postganglionic deurons of the ANS.
- Comprise 99% of all neurons.
- Located exclusively in the CNS.
- Perform all functions of the CNS such as: processing sensory information; sending our commands to effector organs; carrying out complex functions (ie. memory and emotion).
Describe the the structural organization of the CNS.
- Nuclei : groups of cell bodies.
- Pathways, tracts, and commissures : bundles of axons.
Describe the the structural organization of the PNS.
- Ganglia : clusters of cell bodies.
- Nerves : bundles of axons.
Describe glial cells.
- Comprise 90% of all cells in the nervous system.
- Provide structural integrity.
- Necessary for neurons to carry out their functions.
What role do astrocytes play in the body?
Formation of the blood brain barrier.
What role do Ependymal cells play in the body?
These line the ventricles and make cerebrospinal fluid.
What role do Microglia play in the body?
Provide pathogen protection.
What role do Oligodendrocytes play in the body?
These form several sections of myelin sheaths in the CNS.
What role do Schwann cells play in the body?
These mylinates on section of an axon in the PNS.