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Human Anatomy 2.1
The Nervous System
| Term | Definition |
|---|---|
| Major components of the nervous system | Brain, spinal cord, spinal nerves, ganglia, enteric plexuses, and sensory receptors. |
| Nerve | A bundle of axons located outside the brain and spinal cord. |
| Ganglia | small masses of nervous tissue, consisting of neuron cell body's. Located outside brain and spinal cord. |
| Enteric plexuses | Networks of neurons located in the walls of GI tract organs. Help regulate digestive system activities. |
| Sensory receptors (PNS) | Monitor changes in internal and external environments. Information being transmitted by sensory neurons to the brain or spinal cord. Structurally either unipolar or bipolar. |
| Motor neurons (CNS) | Respond to integration decisions by initiating actions in effectors. Structurally multipolar neurons, in the spinal cord. |
| Integrative or interneuron (CNS) | Analyze sensory information, store aspects, make decisions on behavior. Structured multipolar, in spinal cord, and most prevalent in CNS. |
| Central nervous system (CNS) contains | Brain and spinal cord. |
| Peripheral nervous system (PNS) contains | Everything but the brain and spinal cord. |
| Autonomic nervous system (PNS) | Automatic, communicates with internal organs and glands. |
| Somatic nervous system (PNS) | Chooses, communicated with sense organs and voluntary muscles. Touch. |
| Sympathetic division (PNS / Autonomic) | Arousing, fight-or-flight. |
| Parasympathetic division (PNS / Autonomic) | Calming, rest and digest. |
| Sensory / Afferent nervous system (PNS / Somatic) | Sensory input. Nerve fiber. |
| Motor / Efferent nervous system (PNS / Somatic) | Motor output. Nerve fiber. |
| Neurons | Perform most nervous system functions, Generate and transmit nerve impulses. |
| Neuroglia (CNS) | Support, nourish, and protect neurons, maintain interstitial fluid that bathes neurons. Supporting cell of CNS. Engulfs microbes and destroys debris, dead tissue, and pathogens. Can multiply and divide. |
| 3 major parts of a neuron | Dendrites, axon, cell body or soma. |
| Soma | Contains nucleus surrounded by cytoplasm, nissil bodies (RER), neurofibrils / microtubules. |
| Dendrites | Short, tampering, unmyelinated, highly branched process that emerges from cell body. Receive or input portion of a neuron. Dendritic spines. |
| Axon | Long, thin, cylindrical process, may be myelinates. Transmits nerve impulses away from the cell body. Surrounded by myelin sheath. |
| Axoplasm | Line throughout axon, surrounded by axolemma. |
| The order that a multipolar neuron sends and receives nerve impulses | Starts at dendrites, cell body, axon hillock, trigger zone (initial segment), axon, axon terminal, synapse, ends at second neuron (effector). |
| Synapse | The junction between two neurons. |
| Presynaptic neuron | Transmits nerve impulses towards synapse. |
| Postsynaptic neuron | Receives nerve impulses from synapse. |
| Synapse between motor neuron and muscle fiber | Neuromuscular junction. |
| Synapse between neuron and glandular cell | Neuroglandular junction. |
| Synapse cleft | Small gap between cells in synapse. |
| Neurons can be classified by | Number of processes extending from cell body. |
| Multipolar neurons | Several dendrites, one axon. In brain and spinal cord. Many processes associated with cell body. |
| Bipolar neurons | One dendrite, one axon. Rare and located in retina, inner ear, and olfactory area of brain. Has two cell processes. |
| Unipolar neurons | One short process that extends from cell body and divides. |
| 4 kinds of neuroglia in CNS | Astrocytes, Oligodendrocytes, Microglia, Ependymal. |
| Astrocytes (CNS) | Star-shaped cells with many processes. Perform several functions to support neurons, regulate chemical environment, |
| Oligodendrocytes (CNS) | Have a few processes, produce myelin sheath. Each one can myelinate several axons. |
| Ependymal (CNS) | Lines brain ventricles and central canal of spinal cord. Secrete and aid in circulation of cerebrospinal fluid, form blood-cerebrospinal fluid barrier. Form and move CFS. |
| 2 kinds of neuroglia in PNS | Schwann cells and satellite cells. |
| Schwann cells (PNS) | Produce myelin sheaths, wraps around axon. |
| Nodes of Ranvier (PNS) | Gaps in the myelin sheath. |
| Satellite cells (PNS) | Surround cell body's of neurons. Provide structural support, regulate chemical environment between neuron body cells and interstitial fluid. |
| Axons that lack a myelin sheath are: | unmyelinated |
| Myelin sheath | Produced by Schwann cells and oligodendrocytes, surrounds axons. |
| Grey matter | Where cells are, lining the brain on the outside, and a butterfly shape in the middle. Contains dendrites, cell bodies, unmyelinated axons, axon terminals, and neuroglia. Thin layer covers cerebrum and cerebellum. |
| White matter | Surrounds butterfly shape of gray matter that is in the middle of brain. Aggregations of unmyelinated and myelinated axons. Makes up most nerves and tracts. |
| Nerve fibers that are gray in color | Unmyelinated fibers. |
| Long-diameter axons transmit impulses the fastest | Myelinated fibers. |
| Diverging circuit | A presynaptic neuron forms synapses with several postsynaptic cells. |
| Converging circuit | Several presynaptic neurons form synapses with a single postsynaptic neuron. |
| Reverberating circuit | Once a presynaptic neuron is stimulated, it will cause the postsynaptic neuron to transmit a series of nerve impulses. |
| Parallel after-discharge circuit | A single presynaptic neuron stimulates a group of neurons, all of which form synapses with a common postsynaptic neuron. |
| Plasticity | The capability to change based on experience. |
| Regenerate | Limited in neurons, the capability to replicate or repair. |
| Nerogenesis | The formation of new neurons from stem cells, occurs in the adult hippocampus, has not been known elsewhere. |
Created by:
LaurenNeer
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