Neural Tissue
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50 terms
Terms | Definitions |
|---|---|
 CNS Central Nervous System | made up of the brain and spinal cord |
| PNS Peripheral Nervous System | made up of the neural tissue outside of the CNS |
| Cranial Nerves | coming off the brain directly |
| Spinal Nerves | coming off the spinal cord directly |
| Afferent Division | carrying nerve impulses from the sensory receptors to the CNS |
| Efferent Division | carrying nerve impulses from the CNS to muscles, visceral organs, and glands |
| SNS Somatic Nervous System | skeletal muscle |
| ANS Autonomic Nervous System | cardiac muscle, smooth muscle, glandular tissue |
| Neurons | cells that transmit nervous impulses |
| Soma | cell body of a neuron |
| Perikaryon | cytoplasm of a neuron |
| Dendrites | highly branched processes which carry nervous impulses toward the some |
| Axon | long cytoplasmic process which carries nervous impulse away from the some |
| Synaptic Terminal AKA - Synaptic Knob / Axon Terminal | end of an axon which interacts with another cell at the synapse |
| Synapse | junction between a neuron and another cell |
| Bipolar Neuron | has one long axon and one long dendrite, positioned at opposite of the some; occurs in special sense organs |
| Unipolar Neuron AKA - Pseudounipolar | appears to have one process which bifurcates into an axon and a single dendrite; most sensory neurons |
| Multipolar Neuron | has one long axon and many dendrites; most common type of neuron in the CNS |
| Anaxonic Neuron | small with a short axon not easily distinguished from the dendrites; primarily found in the brain and in special sense organs |
| Sensory Neurons | cells of the afferent division of the PNS |
| Motor Neurons | cells of the efferent division of the PNS |
| Interneurons AKA - Association Neurons | may act as connectors between sensory and motor neurons; located entirely within the CNS |
| Neuroglia | support cells of the nervous system 1. hold in place 2. immune cells 3. help do their job |
| Ependymal Cell | epithelial cells of the CNS, lining the ventricles of the brain and the central canal of the spinal cord; some specialized ependymal cells secrete cerebrospinal fluid CSF |
| Astrocyte | support cell for neurons in the CNS; a component of the 'blood-brain barrier', scaffolding cell |
| Microglia | the 'immune system' cells in the CNS |
| Oligodendrocyte | processes wrap around axons of the CNS., insulating them |
| Myeline | the multi-layered membranous wrapping formed by the oligodendrocyte; increases the speed of action potential propagation along the axon |
| Satellite Cells | surround and provide support for neuron cell bodies within a ganglion of the PNS (packing material) |
| Ganglion | a cluster of neuron cell bodies of the PNS |
| Schwann Cells | myelinated cell the wraps entirely around the axons of the PNS |
| Resting potential of the cell membrane of a neuron | 1. Uneven distribution of cations on either side of the cell membrane 2. Inner surface of cell membrane is said to be 'polarized' 3. Resting potential = -70mV |
| Local changes in the cell membrane's resting potential | 1. Hyperpolarizing (more negative) vs. Depolarizing (less negative) 2. Graded potential 3. Summation 4. Threshold Potential |
| Graded Potential | amount of change is directly proportional to the size of the stimulus |
| Summation | local changes in membrane potential can be additive if they occur close together in time or space |
| Threshold Potential | potential at which sodium-channels open, allowing sodium ions to readily enter the cells; depolarization to -60mV to -55mV (for neurons) |
| Action Potential | wave of depolarization that is propagated across an entire cell membrane (nervous/electrical impulse) |
| The All or None Principle | the properties of the action potential are independent of the relative strength of the depolarizing stimulus as long as that stimuls exceeds the threshold (when the door is open, it is open - signal travels or it doesn't) |
| Generation of an Action Potential | 1. Depolarization of the membrane to threshold potential 2. Activation of the sodium channels, allowing sodium ions to enter the cell and membrane to depolarize entirely 3. Sodium channels close and potassium channels reopen, causing the membrane to polarize again 4. Resting potential is re-established and normal ion permeability is restored |
| The Synapse | junction between a neuron and another cell |
| Synaptic Transmission | transmission of neural impulse from one cell to another |
| Presynaptic membrane | part of the synaptic terminal that releases neurotransmitters into the synaptic cleft |
| Synaptic Cleft | space between two cells |
| Neurotransmitters | diffuses across the synaptic cleft and reacts with the postsynaptic membrane |
| Postsynaptic Membrane | 1. depolarized, generating propagation of an action potential 2. hyperpolarized, inhibiting propagation of an action potential * the effect depends on the properties of the receptor (not the neurotransmitter) |
| The Neuromusclar Junction | 1. Modification of the sacrolemma into the motor end plate (between motor neuron and skeletal muscle cells) 2. Motor Unit 2. Clinical Considerations |
| Motor Unit | single motor neuron plus the muscle fibers that are innervated by it |
| Myasthenia Gravis | auto-immune disease causing muscle weakness (face, neck, eyes) genetic, women, age 20-40, blocks receptors no matter how much neurotransmitter is sent |
| Botulism | neurotoxin prevents muscles contraction by preventing release of neurotransmitter from the motor neuron (no signal is sent) ex. Botox |
| Tetanus | neurotoxin causes excessive stimulation of a target muscle which results in severe muscle spasms and sustained muscle contractions (excess signals) |
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