Cultural Literacy. Knowledge Rehab. National Capitals. People You Should Know. Sports Trivia. Flashcards in Chapter 18 Deck Loading flashcards Afferent division B.
Autonomic nervous system C. Central nervous system D. Efferent nervous system E. Parasympathetic division F. Peripheral nervous system G. Somatic nervous system H. Sympathetic division. Central nervous system Pg Peripheral nervous system Pg Afferent division Pg Sympathetic division Pg Somatic nervous system Pg Autonomic nervous system Pg Efferent nervous system Pg Parasympathetic division Pg Astrocyte B.
Oligodendrocyte D. Schwann cell. Microglia Pg Astrocyte Pg Schwann cell Pg Oligodendrocyte Pg Schwann cell Pg Oligodendrocyte Pg Axon B.
Dendrites C. Both A and B D. None of the above. Both A and B Pg Which of the following conduct impulses toward the cell body? Axons B. Nissl bodies D. Dendrites Pg A neuron with one axon and several dendrites is a: A. Multipolar neuron B. Unipolar neuron C. Others, such as jellyfish, lack a true brain.
The insect nervous system is more complex, but also fairly decentralized. It contains a brain, ventral nerve cord, and ganglia clusters of connected neurons.
These ganglia can control movements and behaviors without input from the brain. Octopi may have the most complicated of invertebrate nervous systems. They have neurons that are organized in specialized lobes and eyes that are structurally similar to vertebrate species. Various nervous systems : a In cnidarians, nerve cells form a decentralized nerve net. Mollusks, such as squid and e octopi, which must hunt to survive, have complex brains containing millions of neurons. In f vertebrates, the brain and spinal cord comprise the central nervous system, while neurons extending into the rest of the body comprise the peripheral nervous system.
Compared to invertebrates, vertebrate nervous systems are more complex, centralized, and specialized. While there is great diversity among different vertebrate nervous systems, they all share a basic structure: a CNS and a PNS. One interesting difference between the nervous systems of invertebrates and vertebrates is that the nerve cords of many invertebrates are located ventrally near the abdomen , whereas the vertebrate spinal cords are located dorsally near the back.
The nervous system is made up of neurons, specialized cells that can receive and transmit chemical or electrical signals, and glia, cells that provide support functions for the neurons by playing an information processing role that is complementary to neurons. A neuron can be compared to an electrical wire: it transmits a signal from one place to another.
Glia can be compared to the workers at the electric company who make sure wires go to the right places, maintain the wires, and take down wires that are broken. Although glial cells support neurons, recent evidence suggests they also assume some of the signaling functions of neurons.
Four major types of neurons transmit signals through the body via specialized structures such as dendrites, axons, and synapses. The nervous system of the common laboratory fly, Drosophila melanogaster , contains around , neurons, the same number as a lobster. This number compares to 75 million in the mouse and million in the octopus.
A human brain contains around 86 billion neurons. Despite these very different numbers, the nervous systems of these animals control many of the same behaviors, from basic reflexes to more complicated behaviors such as finding food and courting mates.
The ability of neurons to communicate with each other, as well as with other types of cells, underlies all of these behaviors. Most neurons share the same cellular components. But neurons are also highly specialized: different types of neurons have different sizes and shapes that relate to their functional roles. Each neuron has a cell body or soma that contains a nucleus, smooth and rough endoplasmic reticulum, Golgi apparatus, mitochondria, and other cellular components.
Neurons also contain unique structures, relative to most cells, which are required for receiving and sending the electrical signals that make neuronal communication possible. Dendrites are tree-like structures that extend away from the cell body to receive messages from other neurons at specialized junctions called synapses. While some neurons have no dendrites, other types of neurons have multiple dendrites. Dendrites can have small protrusions called dendritic spines, which further increase surface area for possible synaptic connections.
Cellular structure of neurons : Neurons contain organelles common to many other cells, such as a nucleus and mitochondria. They also have more specialized structures, including dendrites and axons. These choices will be signaled globally to our partners and will not affect browsing data. We and our partners process data to: Actively scan device characteristics for identification.
I Accept Show Purposes. Was this page helpful? Thanks for your feedback! Sign Up. What are your concerns? Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Eyesenck, M. Simply Psychology.
Coon, D. Belmont, CA: Wadsworth; Related Articles. What Is the Somatic Nervous System? They are sometimes referred to as fibers.
Dendrites are usually, but not always, short and branching, which increases their surface area to receive signals from other neurons. The number of dendrites on a neuron varies.
They are called afferent processes because they transmit impulses to the neuron cell body. There is only one axon that projects from each cell body. It is usually elongated and because it carries impulses away from the cell body, it is called an efferent process. An axon may have infrequent branches called axon collaterals. Axons and axon collaterals terminate in many short branches or telodendria. The distal ends of the telodendria are slightly enlarged to form synaptic bulbs.
Many axons are surrounded by a segmented, white, fatty substance called myelin or the myelin sheath. Myelinated fibers make up the white matter in the CNS , while cell bodies and unmyelinated fibers make the gray matter.
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