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Plasma Membrane
- * Barrier to cell contents
- * Double layered
- * Embedded with proteins, Cholesterol, and Glycoproteins
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What happens when potassium moves out?
- * The change in voltage is known as an action potential
- Function of the nervous system
- * Sensory: monitor changes that occur outside and inside the body
- * Integration: process the information
- * Motor: sends response
- 1. Receive
- 2. Process
- 3. output
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How does a signal travel from one neuron to another?
- * Neurons from chemical connetions called synapse
- * Axon terminals of one neuron (presynapse=send) from a synapse with the dendrites of another neuron (postsynapse=receive)
- * The space in between the two neurons is called the synapse cleft
- Functional classification of neurons
- * Sensory: known also as Afferent INPUT
- o Neurons that carry information to the CNS
- o Seeing hearing touching etc
- * Motor: known also as Efferent OUTPUT
- o Neurons that carry information away from the CNS
- o Moving muscles, smiling, exhaling, taking notes, etc.
- o Could be somatic (voluntary) or automatic (involuntary)
- * Interneurons: known as association neurons
- o Found in the CNS
- o Connected to sensory and motor neurons
- o [responsible for integrating ]
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Anatomy of synapse
- * Axon terminals of the presynapse cell contain vesicles
- * These vesicles are filled with chemicals known as neurotransmitters
- [Communication between neurons are mediated by NT]
- * Upon stimulation the NT are released into the Synapse cleft
- * The NT binds to the protein channels on the postsunaptic neuron causing it to be activated
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Components of the nervous system
- * Central nervous system (CNS)
- o Brain & spinal cord
- * Peripheral nervous system (PNS)
- o Cranial and spinal nerves
- * The functional nervous cells are called neurons
- * Two major types of cells
- o Neurons (excitable cells)
- o Neurogial cells (support cells)
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Nerve
- * Made of many axon bundled together
- * Surrounded by connective tissue called epineurium
- * Made of many fascicles
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Structure of a neuron
- * Cell body is the central command cell where the nucleus is located
- * Dendrites are extensions of the cell body that receives electrical signals
- * Axons conduct impulses away from cell body
- * Axon terminals contain vesicles filled with neurotransmitters
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Neurons and Glial
- * Schwann cells produce myelin that insulate the axon
- * Nodes of Ranvier are gaps in myelin sheath along the axon
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What ions are found around the neuron?
- * Sodium is found outside the neuron
- * Potassium is found inside the neuron
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Structure of a nerve
- * Each fascicle is surrounded by a membrane called perineurium
- * Within in each facsicle, many nerve fibers are grouped
- * Each nerve fiber is surrounded by a membrane called endoneurium
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How neurons work together
- * Sensory neurons, receive a signal and send it from the PNS to the CNS
- * Interneurons in the CNS receive the signal and send it to motor neurons
- * Motor neurons send signal out of the CNS to PNS causing a response
- Structural classification of neurons
- * Multipolar neurons:
- o Have many dendrites
- o Found in the brain and spinal cord
- * Bipolar neurons
- o Have two processes
- o One is an axon, the other is a dendrite
- o Found in eyes, nose, and ears
- * Unipolar neurons
- o Have single branches into two
- o The cell bodies aggregate forming ganglia
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Resting potential
- * Both sodium and potassium move by diffusion
- * When permitted, sodium moves into the cell and potassium moves out of the cell
- * Since Na+ and K+ are positively charged, when Na moves in, the cell becomes more positive
- * When K moves out, the cell becomes less positive (more negative)
- * At rest, Na is outside the cell
- * K is inside the cell
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Component of the nervous system
- * Two types of cells
- o Neurons
- o Neuroglial cells [support cells]
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Diffusion
- * Molecules or ions move from region of high concentration to a region of low concentration
- * The difference in concentration is known as concentration gradient
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Types of neuroglial cells
- * Astrocytes
- o Star-shaped cells
- o Most abundant
- o Form between capillaries and neurons
- o Control the concentration of ions within the tissue
- [fascilitated]
- * Microglia
- o Spider-like phangocytes
- o Dispose of debris
- [Protection]
- * Ependymal cells
- o Lines the cavities of the brain and spinal cord
- o Circulated cerebrospinal fluid
- * Oligodendrocytes
- o Produce myeline sheath around nerve fibers in the CNS
- [Myeline]
- * Satelite cells
- o Protect cell body of neurons
- * Shwann cells
- o Form myelin sheath in the PNS
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Neuron
A neuron is a cells that has a unque shape and structure
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