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Nerves 1
| Term | Definition |
|---|---|
| Sensation | Sensory organs receive information about the internal and external environments, and transmits messages to the spinal cord and the brain |
| Integration | Brain and spinal cord processes information from sensory organs; "What does this mean? What is the appropriate reaction?" |
| Response | Brain and spinal cord issues commands to effector organs in order to react to the stimulus |
| Central nervous system | Consists of the brain and spinal cord, enclosed by cranium and vertebral column |
| Peripheral nervous system | All of the nervous system except for the brain and spinal cord, composed of nerves and ganglia. |
| Nerve | A bundle of nerve fibers wrapped in fibrous connective tissue |
| Ganglion | A knot-like swelling in a nerve where neuron cell bodies are concentrated |
| Excitability | A universal property of neurons; is able to respond to stimuli |
| Conductivity | A universal property of neurons; neurons respond to stimuli by producing electrical signals that are quickly conducted to other cells at distant locations |
| Secretion | A universal property of neurons; able to secrete a neurotransmitter to stimulate another cell |
| Afferent Neuron | Sensory neurons that conduct responses to the CNS from the sensory organs |
| Interneuron | Neurons in the brain and spinal cord that receives signals from many neurons and carries out integrative function |
| Efferent Neuron | Motor neurons that conduct signals away from the CNS to effector organs |
| Soma | Cell body and control center of the neuron; has a single, centrally located nucleus with large nucleolus |
| Cytoplasm | Contains organelles, numerous inclusions, and an extensive rough ER and cytoskeleton |
| Cytoskeleton | Consists of dense mesh of microtubules and neurofibrils; compartmentalizes rough RE into Nissil Bodies |
| Neurofibrils | Bundles of actin filaments found tin neuron cytoskeleton |
| Inclusions | Glycogen granules, lipid droplets, melanin, and lipofuscin |
| Lipofuscin | A golden brown pigment produced when lysosomes digest worn-out organelles; accumulates with age in neurons |
| Dendrites | Vast number of branches coming from a few thick branches from the soma; primary sites for receiving signals from other neurons |
| Axon | Nerve fiber; originates from the axon hillock on one side of the soma. Unbranched for most of its length, and is specialized for rapid conduction of nerve signals to points remote to soma |
| Axon collaterals | Branches on the axon |
| Axoplasm | The cytoplasm of the axon |
| Axolemma | The plasma membrane of an axon |
| Myelin sheath | Fatty sheaths that enclose the axon, insulating it and speeding up transmissions |
| Terminal arborization | Extensive complex of fine branches that occurs at the distal end of the axon |
| Synaptic knob | Swelling that forms the synapse with the next cell; contains synaptic vesicles full of neurotransmitter |
| Multipolar neuron | The most common neuron, contains one axon and multiple dendrites, and is found in the brain and spinal cord |
| Bipolar neuron | Neuron that contains one axon and one dendrite; found in olfactory cells, retina, and the inner ear |
| Unipolar neuron | Contains a single process leading away from the soma; gathers sensory information from the skin and organs to the spinal cord |
| Anaxonic neuron | Contains many dendrites, but no axon. Helps in visual processes. |
| Glial cells | Cells that support the neurons; outnumbers them by as much as 50 to 1 |
| Oligodendrocyte | Glial cell in the CNS that forms the myelin sheath. |
| Ependymal cell | Glial cell in the CNS that secretes and circulates cerebrospinal fluid |
| Microglia | Glial cell in the CNS that are tiny macrophages, helping to defend the CNS from potential pathogens |
| Astrocyte | Glial cell in the CNS; carries out many functions, such as forming the blood brain barrier, forming a supportive network of tissue and converting blood glucose to lactate for nourishment |
| Nerve growth factors | Helps neurons grow and promotes synapse function; secreted by astrocytes |
| Astrocytosis | Sclerosis; when a neuron is damaged, astrocytes form scar tissue and fill the space formerly occupied by the neuron |
| Schwann cell | Glial cell in the PNS that forms the myelin sheath |
| Satellite cell | Glial cell in the PNS that surrounds the neurosomas in ganglia, insulating it. Also has a job in regulating the chemical environment of neurons |
| Gliomas | Brain cancer that originates from a glial cell |
| Neurilemma | Thick outermost coil of the myelin sheath in a peripheral nerve fiber |
| Nodes of Ranvier | Gaps between myelin segments |
| Internodes | Myelin-covered segments from one gap to the next |
| Initial segment | Short section of nerve fiber between the axon hillock and the first glial cell |
| Trigger zone | The axon hillock and the initial segment; plays an important role in initiating a nerve signal |
| Multiple Sclerosis | Destruction of myelin sheath due to an autoimmune attack; nerve conduction disrupted and sensation hampered |
| Tay-Sachs disease | Hereditary disorder of infants of Eastern European Jewish ancestry, where glycolipid GM2 accumulates and disrupts conduction of nerve signals |
| Mesaxon | Neurilemma wrapping of unmyelinated nerve fibers |
Created by:
Rylyn27463
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